JLU - 2pi - Annual Report 2010 - Justus-Liebig

Transcription

Annual Report 2010
II. Physikalisches Institut
der
Justus–Liebig–Universität
Heinrich–Buff–Ring 14-16
D–35392 Gießen
Tel.: 0641/99 33 260
Fax : 0641/99 33 209
email: Volker.Metag@exp2.physik.uni-giessen.de
http://www.uni-giessen.de/cms/2pi/
Editor: Dr. R. Knöbel
Preface
This annual report summarizes the activities of the research groups at our institute in
2010. The research program covers a broad range from hadron and particle physics to
nuclear physics. Most of the projects are pursued at external accelerator laboratories
including GSI Darmstadt, ELSA (Bonn), MAMI (Mainz), KEK (Japan), BES III (China)
and CERN/LHC. Ideas driving these programs have been worked out together with
postdocs and students in Giessen where also the preparation of the experiments, the
design and development of the experimental equipment and the analysis of the data take
place.
These projects have been funded by research grants from the BMBF, DFG, HGF and
the EU, totalling 1.5 MEuro in 2010. A large number of PhD students and postdocs
were supported by these 3rd. party funds. Results of the research activities have led to
numerous publications and contributions to national and international conferences which
are described and listed in this report.
Apart from ongoing experiments the research groups are heavily involved in preparations
for the planned detectors PANDA and CBM and the NUSTAR experiments at the
International Facility for Antiproton and Ion Research (FAIR). These activities are
coordinated by the Hessian center of excellence HIC-for-FAIR in which the Giessen
groups cooperate with groups at TU Darmstadt, FIAS, Frankfurt University, and GSI.
Members of the institute have played a leading role in interdisciplinary activities at the
Justus-Liebig-University Giessen such as the SEPA initiative studying all aspects of
solar-thermal energy for Europe from deserts in North Africa and the AmbiProbe project
where mass spectrometry techniques developed at our institute are applied in life sciences.
We welcome two new female colleagues and their research groups at our institute: since
Jan. 1st 2010 Dr. Iris Dillmann is heading the Helmholtz Young Investigator group LISA,
working in the field of nuclear structure and nuclear astrophysics. Prof. Dr. Claudia
Höhne was appointed in the framework of HIC-for-FAIR, starting June, 1st 2010. Her
group will focus on the physics of heavy-ion collisions and strengthen the activities in the
preparation of the CBM detector at FAIR. After two attempts to fill the W3 position for
hadron physics had failed, Prof. Dr. Volker Metag was asked to stay in office as senior
professor until September 2012.
The scientific results presented in this report would not have been achieved without the
support of our administrative and technical staff, which is highly acknowledged.
(Volker Metag)
Contents
Members of the institute
7
Theses
11
Group of Prof. Dr. M. Düren
The ATLAS experiment
The HERMES experiment
The PANDA experiment
Colloquia and seminars
Publications
Conference and workshop contributions
15
16
18
19
23
23
28
Group of Prof. Dr. W. Kühn
PANDA
HADES
Bes III
Belle
Belle II
Cluster installation
Publications
31
32
33
34
35
37
37
39
39
44
Group of Prof. Dr. V. Metag
Measurement of the η- transition form factor in the γp → pη → pγe+ e− reaction
Search for ω-mesic states in Boron
In-medium properties of ω mesons in photonuclear reactions
In-medium properties of the ω meson near the production threshold
Developments and preparations for the PANDA-EMC
Publications
48
49
49
51
53
53
56
56
57
Group of Prof. C. Scheidenberger
Super-FRS design status report
Changes of the ashes of an X-ray burst due to better known nuclear masses
Rate acceptance and new anode design for IMS TOF detector
Further advances in the development of a MR-TOF-MS for the LEB
60
61
62
63
64
4
II. Physikalisches Institut Gießen – Jahresbericht 2010
A mobile high-resolution MR-TOF-MS for in-situ analytics
FRS Ion Catcher: Setup, status and perspectives
Publications
66
67
69
69
74
Group of Dr. I. Dillmann
LISA- Lifetime Spectroscopy for Astrophysics
Nuclear physics input for r-process calculations
Experimental situation
Experiments at the GSI radioactive beam facility
Publications
78
79
79
81
82
85
85
86
Group of Prof. Dr. Claudia Höhne (since 06/10)
Development of a RICH detector for the CBM experiment
Publications
89
90
95
95
5
6
Members of the institute
Secretariat:
C. Momberger
D. Musaeus
A. Rühl
Academic:
Dr. A. Astvatsatourov
Dr. H. Berghäuser (since 10/10)
T. Dickel (since 08/2010)
Dr. I. Dillmann
Dr. P. Drexler
Dr. V. Dormenev
Prof. Dr. M. Düren
Dr. K. Föhl
Prof. Dr. Dr. h.c. H. Geissel
Dr. A. Hayrapetan
Dr. S. Heinz
Prof. Dr. C. Höhne
Dr. R. Knöbel
Dr. D. Kresan (since 08/10)
Prof. Dr. W. Kühn
Dr. S. Lange (AR)
Dr. Y. Liang
Dr. T. Mahmoud (since 12/10)
Prof. Dr. V. Metag
Dr. M. Nanova
Dr. R. Novotny (AkDir)
Dr. W.R. Plaß
Prof. Dr. C. Scheidenberger
Dr. B. Spruck
Dr. H. Stenzel (AR)
Dr. B. Sun
Dr. W. Yu
Technical Support:
S. Ayet (Electronic Engineer)
W. Döring (PTA) (until 6/10)
T. König
T. Köster (PTA)
J. Schneider (IT Systems Manager)
R. Schubert
K. Wolf
A. Zagan (PTA)
Elektronic Workshop:
W. Bonn (Master Craftsman - Communication Engineer)
C. Salz (Electronic Engineer, Leader of Workshop)
M. Straube (Apprentice)
U. Thöring (Electronic Engineer)
7
8
PhD Students:
H. Berghäuser (until 9/10)
D. Bremer (since 4/10)
I. Brodski
T. Dickel (until 07/2010)
F. Dietz (born Hjelm)
T. Eißner
A. A. Evdokimov (since 11/2010)
F. Farinon
S. Friedrich
E. Haettner
C. Jesch
P. Koch
B. Kröck
N. Kuzminchuk
J. Lang (since 02/2010)
B. Lemmer (until 3/10)
K. Makonyi
O. Merle
L. Ming
M. Moritz
D. Münchow
R. F. Perez Benito
F. Pfeiffer
A. Prochazka
B. Riese
M. Thiel
Q. Wang (until 10/10)
Diploma Students:
D. Bremer (until 3/10)
S. Fleischer (since 9/10)
I. Heller
A. Kopp
F. Lautenschläger (until 10/2010)
D. Schäfer (until 04/2010)
T. Schäfer (until 10/2010)
M. Sporleder
M. Zühlsdorf
MSc Students:
S. Darmawi
M. Galuska (since 1/10)
T. Gessler (since 1/10)
K. Kreutzfeldt
S. Künze (since 1/10)
Li Lu (since 9/10)
D. Pelikan
M. Ullrich (since 1/10)
M. Werner (since 1/10)
BSc Students:
9
S. Diehl
E. Etzelmüller
D. Mühlheim
W. Lippert
A.-K. Rink
M. Stahl
N. Stöckmann
D. Wagner (6/10 - 9/10)
M. Wagner (6/10 - 9/10)
Detector and TAPS Laboratory:
Dr. R. Novotny (Leader)
PANDA Laboratory:
Dr. P. Drexler (Leader)
HERMES Laboratory:
Dr. H. Stenzel (Leader)
Mass Spectrometry Laboratory:
Dr. W. Plaß (Leader)
SMD Laboratory:
Prof. Dr. W. Kühn (Leader)
Radiation Protection Officer:
Dr. R. Novotny
Safety Officer:
W. Döring
Data Protection Officer:
Prof. Dr. W. Kühn
Lab Course in Physics:
Prof. Dr. W. Kühn (for Physics’ Students)
Dr. J. S. Lange (for Physics’ Students)
Dr. H. Stenzel (for Students of Natural Sciences)
Dr. R. Novotny (for Medicine Students)
Dr. M. Nanova (for Medicine Students)
Lab Course in Electronics:
Dr. J. S. Lange (Leader of the Lab Course)
10
Theses
PhD theses
Roberto F. Perez Benito
”Exclusive ρ Production measured with the HERMES Recoil Detector”
Henning Berghäuser
”Investigation of the Dalitz decays and the electromagnetic form factors of
the η and π 0 π 0 -meson”
Timo Dickel
”Design and Commissioning of an Ultra-High-Resolution Time-of-Flight Based
Isobar Separator and Mass Spectrometer”
Michaela Thiel
”In-medium properties of the ω-meson studied in photonuclear reaction
near the production threshold”
Diploma theses
Daniel Andreas Bremer
”Reconstruction of Electromagnetic Showers and Determination of the Position
Resolution of a Prototype of the PANDA Electromagnetic Calorimeter”
Ingo Heller
”Inklusive Hadronenspektroskopie in J/Ψ und Ψ′ ”
Felix Lautenschläger
”Entwicklung, Aufbau und Inbetriebnahme eines Energiebunchers für einen
Multireflexions-Flugzeit-Isobarenseparator”
Felix Pfeiffer
”Simulation of the ATLAS ALFA detector in comparison with testbeam data”
Daniel Schäfer
”Design and simulation of a cryogenic stopping cell for the low-energy branch
of the Super-FRS at FAIR”
11
12
Thorsten Schäfer
”Inbetriebnahme und Charakterisierung eines Radiofrequenz-Quadrupol-Bunchers
für SHIPTRAP”
Master Theses
Sabrina Darmawi
”Entwicklung eines Cerenkov-Faserdetektors für das ATLAS Experiment am CERN”
Thomas Gessler
”An IPMI-Based Slow Control System for Data
Acquisition in the PANDA Experiment”
Daniel Pelikan
√
”Observation of W → µν in proton collisions at s = 7 TeV with the ATLAS detector”
Matthias Ullrich
”Classification of Υ(5s) Decays with Self-Organizing
Neural Networks”
Marcel Werner
”Search for new bottomonium(-like) states in e+ e− → B (∗) B̄ (∗) (π)(π)
at the BELLE experiment”
Bachelor theses
Stefan Diehl
”New Readout Concepts of Electromagnetic Calorimeters”
Erik Etzelmüller
”Messung diffaktiver φ+ -Produktion mit dem HERMES-Rückstoßdetektor”
Wayne Lippert
”Concepts for the calibration of a prototype of the electromagnetic calorimeter for PANDA”
Daniel Michael Mühlheim
”Reconstruction of energy and position information with an electromagnetic calorimeter
using PROTO60”
13
Ann-Kathrin Rink
”Messung der unterschiedlichen Photonenpfade in einem DIRC Radiator”
Marian Stahl
”Verfeinerung der Θ+ -Analyse beim HERMES-Experiment”
Nils Stöckmann
”Eigenschaften von dichroitischen Spiegeln als Frequenzfilter im PANDA DIRC-Detektor”
Daniel Wagner
”Implementierung eines schnellen Memory-Controllers für eine FPGA-Architektur
im Rahmen des PANDA-Projekts”
Milan Wagner
”Suche nach Charmoniumzuständen mit Proton-Antiporoton Endzuständen
im Rahmen des Belle-Experiments”
14
Group of Prof. Dr. M. Düren
Secretariat:
D. Musaeus
Academic:
Prof. Dr. M. Düren
Dr. A. Astvatsatourov
Dr. K. Föhl
Dr. A. Hayrapetan
Dr. H. Stenzel (AR)
Dr. W. Yu
Technical support:
T. König
K. Wolf
PhD Students:
I. Brodski
P. Koch
B. Kröck
O. Merle
R. F. Perez Benito
F. Pfeiffer
Diploma Students:
M. Sporleder
M. Zühlsdorf
MSc Students:
S. Darmawi
K. Kreutzfeldt
D. Pelikan
BSc Students:
E. Etzelmüller
A.-K. Rink
M. Stahl
N. Stöckmann
15
16
The ATLAS experiment
The year 2010 was very successful for the LHC and ATLAS with about 50 pb−1 of recorded
√
integrated luminosity in pp running at s=7 TeV, complemented by a first run with heavy
ions, resulting in 14 ATLAS publications using collision data.
The focus of the ATLAS group in Gießen was on the completion of the production of ALFA
scintillating fibre detectors, which was accomplished in summer 2010. All 8 detectors
needed for the operation in LHC were delivered to CERN, plus two partly mounted spare
detectors and about 25 double-sided fibre modules for additional spares. The entire ALFA
system was then station-by-station exposed to a testbeam at cern for a final performance
verification [1]. The data analysis is still ongoing but it was verified that performance
requirements are met and ALFA was installed during the technical stop of the LHC from
December 2010 to January 2011. The installation went well, thanks to a major support
by the CERN accelerator group. A picture of two stations (one arm) of ALFA is shown
in fig. 1.
Figure 1: Two stations of the ALFA detector in the LHC tunnel 240m from the ATLAS interaction
point.
We participate also on a possible upgrade of the forward region of ATLAS through the
AFP project and have made major progress in 2010 on the development of a fast Cerenkov
quartz timing detector for AFP. Several prototypes of a novel quartz fibre detector have
been built and were tested in Jülich, at CERN and at DESY. Different fibre bundle
orientations with respect to the particle incidence were tested as well as different read-out
devices. Most promising for AFP appears a configuration where the fibres are oriented at
the Cerenkov angle of 42◦ and coupled to multi-pixel MCP-PMTs, where the most active
17
fibres receiving the highest radiation are spread over several pixels in order to maximize
the lifetime of the MCP-PMT. The test resulted in a time resolution estimate of about 50
ps [2].
On top of our hardware contribution our group is also involved in the operation of the
luminosity monitors and forward detectors LUCID and ZDC and in the determination
of the online luminosity. In 2010 the absolute luminosity was calibrated using Van der
Meer beam separation scans and an absolute precision of 11% was achieved [3], where the
uncertainty is dominated by the measurement of the beam currents.
Several physics results were obtained on standard model cross sections and our group
contributed to the determination of the cross section of the process pp → W → µν.
Using only a fraction of the recorded data in 2010 the cross section times branching ratio
was determined to be σ × BRW →µν = 9.5 ± 1.2 nb [4], where the uncertainty is already
dominated by systematic effects. The result is in good agreement with the standard model
prediction, as shown in fig.2. Alternatively, assuming the theoretical calculation is correct,
the absolute luminosity was determined from the observed number of signal events and
found to be in good agreement with the directly measured luminosity using the Van der
Meer calibration.
Figure 2: Measurements of the cross section for W → µν production in pp and pp̄ collisions as
function of
√
s compared to theoretical predictions.
18
References
[1] F. Pfeiffer, Simulation of the ATLAS ALFA detector in comparison with testbeam data,
Diploma thesis JLU Giessen 2010
[2] S. Darmawi Entwicklung eines Cerenkov-Faserdetektors für das ATLAS Experiment
am Cern, Master thesis JLU Giessen 2010
[3] G. Aad et al., ATLAS Collaboration, Luminosity Determination in pp Collisions at
√
s=7 TeV Using the ATLAS Detector at the LHCarXiv:1101.2185 [hep-ex]
√
[4] D. Pelikan, Observation of W → µν in proton proton collisions at s=7 TeV with the
ATLAS detector, Master thesis JLU Giessen 2010
The HERMES experiment
Verification of Recoil SFT detector calibration and efficiencies
For the HERMES data production our group responsibility in 2010 was the verification
of SFT (Scintillating Fiber Tracker) calibration and efficiency estimations. The SFT
calibration is very important for the whole Recoil detector not only for tracking but also
for particle identification (PID). The calibration is done in three steps, first every PMT’s
amplitude spectra was fitted and the number of photoelectrons are extracted. In a second
step the clustering algorithm was checked and possible cross-talks identified. In the third
step using minimum ionizing particles(pions) the response for every SFT channel so called
calibration constants were extracted, which then enter into the Recoil detector PID scheme
to separate protons from pions. The identified protons are then used to calculate and check
SFT efficiencies for whole 2006-2007 data taking period. Fig. 3 shows the SFT detector
efficiency against accumulated run (i.e. time). In general the efficiency is high enough
(over 99.5 %) and stable for all four quadrants.
Exotic baryon search
The improved resolution of the HERMES spectrometer in terms of decaying particle resolutions over all periods of data taking allow us to continue our searches for exotic pentaquark
candidate Θ+ in decay channel into proton and Ks with further Ks decay into two charged
pions. The similar analyses was performed on both targets, Hydrogen and Deuterium.
While the preliminary data on Deuterium shows an enhancement in the vicinity of ≈ 1520
MeV (certain theoretical models predict its existence close to that value) the Hydrogen
data, although with ≈ 2 times more statistics accumulated, doesn’t show a similar bump
in that vicinity. The preliminary comparison of two datasets with normalization using
accumulated DIS statistics clearly show the difference in that region, speaking again in
preference of certain models predicting the pentaquark production suppression on Hydrogen target in comparison with Neutron(Deuterium) one. This comparison are depicted in
Fig. 4. Further statistical analyses and fits with various hypotheses should be performed
before this spectra appears for publication.
19
efficiency [%]
100
100
99.5
99.5
99
99
98.5
0
100
20000
98.5
40000 0
100
99.5
99.5
99
99
98.5
0
20000
98.5
40000 0
20000
40000
Space points
Parallel Cluster
Stereo Cluster
20000
40000
Run
Figure 3: Efficiency of the SFT detector for various layers (parallel and stereo) and for
space points (with respect to extrapolated tracks from silicon detectors) for four quadrants
of the Recoil detector. The stability over whole data taking period is evident.
During the reported period we have 9 publications, three conference talks were presented
and one PhD (R. Perez-Benito) thesis and two Bachelor theses were successfully accomplished, with the focus on the analysis of hard exclusive reactions.
The PANDA experiment
The PANDA antiproton experiment at FAIR needs superiour particle identification (PID)
for the scientific programme of hadron spectroscopy in the charmonium energy region.
For the Forward Endcap of the PANDA target spectrometer a Cherenkov detector of the
20
Figure 4: Comparison of Proton-Ks invariant mass spectra for Hydrogen (black histogram)
with Deuterium one (red histogram). The black points show normalized Hydrogen data
using DIS statistics (Thesis M. Stahl).
DIRC principle [1] is proposed as it allows a very compact design.
In the proposed Disc-DIRC design the generated Cherenkov light propagates by total internal reflection through the radiator plate to the photon sensors at the disc rim. There
are two concepts of accessing the Cherenkov angle information, which were exploited
separately by two preceding detector designs. Based on angle-to-position conversion the
focussing light guide design [2] measures the Cerenkov angle by imaging the photons onto
a pixelised photon detector. Based on angle-to-time conversion the time-of-propagation
(TOP) design [3] reconstructs the Cherenkov angle from the photon arrival time differences.
In 2010 we have been working on the 3D-Disc-DIRC-Design combining these two concepts
(see Figure 5). Small light guides at the disc rim allow simultaneous TOP and angle
measurement for each photon. Each quarter section radiator can be manufactured in one
piece. In the T-shaped light guides the photon arrival alternates between top and bottom
sensor areas for increasing photon path lengths, this lifts timing ambiguities. Simulation
code for this design has been written.
21
Figure 5: One quadrant of the Disc-DIRC-3D design equipped with small light guides
around the rim [4].
Figure 6: Y-shaped acrylic glass Cherenkov radiator attaching to two Philips digital
SiPMs.
The 3D-Disc-DIRC-Design assumes using Philips digital silicon photomultipliers that are
currently being developed. They contain the readout electronics including the TDC on
one chip. Each photodiode cell can be individually deactivated. This allows to remove
the signals from the noisiest cells. In 2010, we have started to evaluate prototype SiPM
detectors in test beam experiments using various Cherenkov set-ups. For example the
timing performance has been measured at a test beam time at CERN using a Y shaped
radiator (Fig. 6) and measuring the time difference between the two legs. A single photon
time resolution of σ = 60 ps has been observed.
During the reported period we have 4 publications, and two Bachelor theses (A.-K. Rink
and N. Stöckmann) were successfully accomplished.
[1] The BaBar-DIRC Collaboration, I. Adam et al., The DIRC Particle Identification
System for the BABAR Experiment, Nucl. Instr. and Meth. A 538 (2005) 281
22
[2] K. Föhl et al., The focussing light guide disc DIRC design, 2009 JINST 4 P11026
[3] M. Düren et al., The Panda time-of-propagation Disc DIRC, 2009 JINST 4 P12013
[4] Illustrations from O. Merle, Talk at PANDA Collaboration meeting 12/2010
23
1. M. Düren
Desertec - Strom aus der Wüste
Vortragsreihe Die Welt im Wandel, Uni Marburg, 21.1.2010
2. M. Düren
Desertec- Aufbruch in ein neues Zeitalter der ökologischen Stromversorgung?
Vortrag: Initiative für nachhaltige Entwicklung, HU Berlin, 16.2.2010
3. H. Stenzel
Luminosity and forward physics with ATLAS
Seminar University of Wuppertal, June 28 2010
Publications
1. Transverse momentum broadening of hadrons produced in semi-inclusive
deep-inelastic scattering on nuclei
A. Airapetian et al. [HERMES Collaboration]
Phys. Lett. B 684 (2010) 114.
2. Single-spin azimuthal asymmetry in exclusive electroproduction of pi+
mesons on transversely polarized protons
Phys. Lett. B 682 (2010) 345.
3. Search for a Two-Photon Exchange Contribution to Inclusive DeepInelastic Scattering
Phys. Lett. B 682 (2010) 351.
4. Nuclear-mass dependence of azimuthal beam-helicity and beam-charge
asymmetries in deeply virtual Compton scattering
Phys. Rev. C 81 (2010) 035202.
5. Measurement of azimuthal asymmetries associated with deeply virtual
Compton scattering on an unpolarized deuterium target
Nucl. Phys. B 829 (2010) 1.
24
6. Exclusive Leptoproduction of Real Photons on a Longitudinally Polarised
Hydrogen Target
JHEP 1006 (2010) 019.
7. Effects of transversity in deep-inelastic scattering by polarized protons
A. Airapetian et al. [HERMES collaboration]
Phys. Lett. B 693 (2010) 11.
8. Leading-Order Determination of the Gluon Polarization from high-pT
Hadron Electroproduction
arXiv:1002.3921 [hep-ex]. 2010
9. Measurement of azimuthal asymmetries associated with deeply virtual
Compton scattering on a longitudinally polarized deuterium target
Nucl. Phys. B 842 (2011) 265.
10. Exclusive rho0 production measured with the HERMES recoil detector
R. F. Perez Benito
DESY-THESIS-2010-052
11. Particle identification for the PANDA detector
C. Schwarz et al. [PANDA Cherenkov Group]
Nuclear Instruments and Methods in Physics Research A; In Press, Corrected Proof;
Available online 11 November 2010, DOI: 10.1016/j.nima.2010.10.116
12. Design of a disc DIRC detector for the WASA experiment
K. Föhl for the WASA-at-COSY Collaboration
Available online 27 October 2010, DOI: 10.1016/j.nima.2010.10.054
13. A focussing disc DIRC for PANDA
E. N. Cowie et al. [PANDA Cherenkov Group]
Available online 1 October 2010, DOI: 10.1016/j.nima.2010.09.132
14. Systematic studies of micro-channel plate PMTs
25
A. Lehmann et al. [PANDA Cherenkov Group]
Available online 29 September 2010, DOI: 10.1016/j.nima.2010.09.071
15. Simulation of the ATLAS ALFA detector in comparison with testbeam
data
F. Pfeiffer
Diploma thesis JLU Giessen 2010
16. Entwicklung eines Cerenkov-Faserdetektors für das ATLAS Experiment
am Cern
S. Darmawi
Master thesis JLU Giessen 2010
17. Observation of W → µν in proton proton collisions at
ATLAS detector
√
s=7 TeV with the
D. Pelikan
Master thesis JLU Giessen 2010
18. Luminosity Determination in pp Collisions at
LAS Detector at the LHC
√
s=7 TeV Using the AT-
ATLAS Collaboration, G. Aad et al.
arXiv:1101.2185 [hep-ex]
19. Measurement of the W → lν and Z/γ ⋆ → ll production cross sections in
√
proton-proton collisions at s=7 TeV with the ATLAS detector
JHEP 12 (2010) 060.
20. Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton
Collisions with the ATLAS Detector at the LHC
Phys. Rev. Lett. 105 (2010) 161801.
21. Performance of the ATLAS Detector using First Collision Data
ATLAS Collaboration, G. Aad et al
J. High Energy Phys. 09 (2010) 056.
22. The ATLAS Simulation Infrastructure
26
Eur. Phys. J. C 70 (2010) 823-874.
23. Charged-particle multiplicities in pp interactions at
sured with the ATLAS detector at the LHC
√
s = 900 GeV mea-
Phys. Lett. B 688 (2010) 21-42.
24. Measurement of the centrality dependence of J/Ψ yields and observation
of Z production in lead-lead collisions with the ATLAS detector at the
LHC
arXiv:1012.5419
25. Search for Diphoton Events with Large Missing Transverse Energy in 7
TeV Proton-Proton Collisions with the ATLAS Detector
arXiv:1012.4272
26. Measurement
pof the inclusive isolated prompt photon cross section in pp
collisions at (s) = 7 TeV with the ATLAS detector
arXiv:1012.4389
27. Charged-particle multiplicities in pp interactions measured with the ATLAS detector at the LHC
arXiv:1012.5104
28. Measurement of the top quark-pair production cross section with ATLAS
√
in pp collisions at s = 7 TeV
arXiv:1012.1792
29. Measurement of underlying event characteristics using charged particles
√
in pp collisions at s = 900 GeV and 7 TeV with the ATLAS detector
arXiv:1012.0791
30. Studies of the performance of the ATLAS detector using cosmic-ray
muons
27
Eur. Phys. J. C71 (2011) 1593.
31. Search for Quark Contact Interactions in Dijet Angular Distributions in
pp Collisions at sqrt(s) = 7 TeV Measured with the ATLAS Detector
Phys. Lett. B694 (2011) 327-345.
32. Measurement of inclusive jet and dijet cross sections in proton-proton
collisions at 7 TeV centre-of-mass energy with the ATLAS detector
Eur. Phys. J. C71 (2011) 1512
33. Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton
Collisions with the ATLAS Detector at the LHC
Phys. Rev. Lett. 105 (2010) 161801.
34. Readiness of the ATLAS Tile Calorimeter for LHC collisions
Eur. Phys. J. C70 (2010) 1193-1236.
35. Commissioning of the ATLAS Muon Spectrometer with Cosmic Rays
Eur. Phys. J. C70 (2010) 875-916.
36. Performance of the ATLAS Detector using First Collision Data
JHEP 1009 (2010) 056.
37. The ATLAS Simulation Infrastructure
Eur. Phys. J. C70 (2010) 823-874.
38. The ATLAS Inner Detector commissioning and calibration
Eur. Phys. J. C70 (2010) 787-821.
39. Drift Time Measurement in the ATLAS Liquid Argon Electromagnetic
Calorimeter using Cosmic Muons
28
Eur. Phys. J. C70 (2010) 755-785.
40. Readiness of the ATLAS Liquid Argon Calorimeter for LHC Collisions
Eur. Phys. J. C70 (2010) 723-753.
1. Management Events:
henkammer, 6.5.2010
M. Düren
StrategieCircle Energie, Akademie Schloss Ho-
Innovative Projekte der erneuerbaren Energien; DESERTEC - Strom aus der Wüste
2. Desert Sun - Yours, Mine, Ours? Workshop on Solar Energy Partnership
Africa Europe, Gießen, 8.-9.11.2010
M. Düren
SEPA and the DESERTEC Concept - Is Academic Research still needed?
3. AFRIKA - der unterschätzte Kontinent; Verband deutscher Schulgeographen, Bildungszentrum Tannenfelde, 17./18.12.2010
M. Düren
Afrikas Sonne - Europas neue Stromquelle: Desertec - eine Win-Win-Situation?
4. Dii Desert Energy Conference, Barcelona, 26.11.2010
M. Düren
Summary of panel III: Economic and social development in MENA
5. EnergEthik Tagung für Schülerinnen und Schüler, Univ.
2010.12.10
Giessen,
M. Düren
Desertec - Strom aus der Wüste
6. SPIN2010, 19th International Spin Physics Symposium September 27,
October 2, 2010, Jülich, Germany
M. Düren
Deeply Virtual Compton Scattering off polarised and unpolarised protons at HERMES
29
7. Frühjahrstagung der DPG, Hadronen und Kerne, March 15-19, 2010,
Bonn, Germany
R. Perez Benito
Exclusive rho0 production with the Recoil Detector at HERMES and b-slopes
O. Merle
Der Time of Propagation Disc DIRC für PANDA
B. Kröck
Test von Disc DIRC Prototypen mit kosmischen Teilchen und Protonenstrahlen
F. Pfeiffer
Testbeam data analysis for ALFA
8. Herbstschule für Hochenergiephysik in Maria Laach, September 5 - 15,
2010 Benediktinerkloster Maria Laach, Germany
I. Brodski
Messung generalisierter Partonverteilungen bei HERMES und PANDA
9. Workshop on timing detectors, Krakow, Poland November 29-December
1, 2010
B. Kröck
Fast timing detectors
10. Annual meeting of the German ATLAS groups, Mainz, September 22-24,
2010
D. Pelikan
√
Observation of W → µν in proton collisions at s = 7 TeV with the ATLAS detector
11. Detector Workshop of the Helmholtz Alliance Physics at the Terascale,
Heidelberg, October 4, 2010
A. Astvatsatourov
ATLAS Forward Detectors
A. Hayrapetyan
New Digital SiPMs from Philips: Applications and First Tests
30
Group of Prof. Dr. W. Kühn
Secretariat:
C. Momberger
Technical support:
T. Köster
Academic:
Prof. Dr. W. Kühn
Dr. S. Lange (AR)
Dr. B. Spruck
Dr. Y. Liang
PhD Students:
D. Münchow
L. Ming
Q. Wang (until 10/10)
Diploma Students:
I. Heller
A. Kopp
S. Fleischer (since 9/10)
MSc Students:
M. Galuska (since 1/10)
T. Gessler (since 1/10)
S. Künze (since 1/10)
Li Lu (since 9/10)
M. Ullrich (since 1/10)
M. Werner (since 1/10)
BSc Students:
D. Wagner (6/10 - 9/10)
M. Wagner (6/10 - 9/10)
Visitors:
Prof. Dr. Liu, ZhenAn
Xu, Hao
31
32
The group of Prof. Dr. Kühn is involved in the following experiments:
the HADES experiment at GSI accelerator S.I.S. (Schwer-Ionen Synchrotron) in
Darmstadt, Germany, studying p + p, p + A, A + A and π + A reactions for beam
energies ≤3.5 AGeV,
the PANDA experiment at the future GSI accelerator FAIR (Facility for Antiproton
and Ion Research) in Darmstadt, Germany, studying p + p and p + A collisions for
antiproton beam momenta ≤ 15 GeV/c,
the BES-III experiment at the BEPC (Beijing Electron Positron Collider) accelerator
√
in Beijing, China, studying e+ e− collisions at s=2.2-4.3 GeV,
the BELLE experiment at the KEK-B accelerator in Tsukuba, Japan, studying e+ e−
√
collisions at s=10.52 - 10.86 GeV, and
the future BELLE II experiment in Tsukuba, Japan, studying e+ e− collisions at
√
s=10.52 - 10.86 GeV.
PANDA
The X(3872) is a charmonium(-like) state which was first observed in its decay
X(3872)→J/ψπ + π − in B decays [2][3] and inclusive production in pp collisions [4][5].
In particular, the observation of its radiative decay into J/ψγ allows the assignment
of positive charge parity C=+1. The observation of isospin violation in the decay
X(3872)→J/ψρ(→π + π − ) raised the question, if it might be a charmonium state at all.
0∗
As its mass is within ∆m<1 MeV of the D 0 D threshold, it might be interpreted as
an S-wave molecular state [1]. The width is unknown and probably can only be determined at PANDA. The current upper limit is Γ≤2.3 MeV [2], whereas PANDA might
be able to set an upper limit in the order of a few hundred keV using the cooled antiproton beam. A detailed simulation of a resonance scan of the X(3872) in the reaction
pp→X(3872)→J/ψπ + π − using the PandaRoot framework was carried out. The main
background is meson production in processes such as pp→π + π − π + π − with two misidentified charged pions (as leptons) in the EMC. The cross section for this process is 50 µb [6],
i.e. a factor ≃103 larger than the signal. It is important to investigate the shape of the
background e.g. in the 2-particle mass spectrum. For this purpose, a DPM (dual parton
model) event generator [7] was used. In fact, a varying background shape in the region of
the J/ψ was found and fitted with a first order Chebyshev polynomial. The background
fit was performed for the sideband, and the fitted background was subtracted in the signal
and sideband region. Fig. 1 shows the background fit subtracted signals of the tagged J/ψ
from the X(3872) decay. Details of the analysis are described elsewhere [8].
[1] N. A. Tornqvist, Phys. Lett. B590(2004)209, Phys. Rev. Lett. 67(1991)556
[2]Belle Collaboration, Phys. Rev. Lett. 91(2003)262001
[3]BaBar Collaboration, Phys. Rev. D71(2005)071103
33
Figure 7: MC simulation of a resonance scan of the X(3872) at PANDA, with 9 scan points
of different anti-proton beam momenta and data taking of 2 days for each point. The plots
show the background subtracted, tagged J/ψ→e+ e− signal from the X(3872)→J/ψπ + π −
decay. Only statistical errors are shown.
[4]CDF-II Collaboration, Phys. Rev. Lett. 93(2004)072001
[5]D0 Collaboration, Phys. Rev. Lett. 93(2004)162002
[6]V. Flaminio et al., CERN-HERA-79-03
[7]V. Uzhinsky, A. Galoyan, hep-ph/0212369,
and references therein
[8]J. S. Lange et al., arXiv:1010.2350
HADES
The High-Acceptance DiElectron Spectrometer (HADES) is in operation at the GSI
Helmholtzzentrum für Schwerionenforschung in Darmstadt. It was designed for studying the modification of hadron properties in a strongly interacting medium. HADES
measures the in-medium masses and widths of the light vector mesons produced in pion,
proton and heavy-ion induced collisions. The study of the rare dielectron decay of these
mesons requires a sophisticated trigger system.
The Compute Node is foreseen as a computation platform in a possible upgrade of the
HADES data acquisition system. It could provide on-line track recognition for the trigger.
Other experiments like Belle II and PANDA will make use of the Compute Node as well,
34
possibly requiring a larger number of boards. In a network of multiple Compute Nodes, fast
interconnects between the boards and an adequate hardware infrastructure are required.
These are two of the reasons why AdvancedTCA was chosen as the hardware architecture
for the Compute Node. A single AdvancedTCA shelf can house up to 14 Compute Nodes
and provides power and cooling. In a shelf with a full-mesh backplane, each board is
linked to every other board directly with a high-speed connection. Three such shelves are
currently available in our work group for testing purposes.
A central Shelf Manager regulates the power distribution, temperature and cooling etc.
for the entire shelf. It needs to keep track of which kind of board is installed in each of
the shelf’s slots at all times. The Shelf Manager gathers information about board type,
status, health etc. by exchanging IPMI messages with the boards. A small piggy-back
board, the IPM Controller (IPMC), represents the Compute Node in communication with
the Shelf Manager. It supervises the health (temperature and voltages) of the Compute
Node, controls its power supply, the FPGA programming process and other hardware
management issues.
A first version of the IPMC was designed in late 2008, based on an Atmel ATmega1280
microcontroller. Additional ICs were used to connect the microcontroller to the various
I2 C buses. The PCB measured 75 mm × 35 mm . PCBs were ordered from an external
company, and two prototypes of the board were built using our SMD manufacturing
facilities. Some hardware bugs were provisionally fixed in the second prototype. Firmware
for the microcontroller was written in C++ using various open source tools. The firmware
allows sensor read-out, the sending and receiving of various IPMI messages, hardware
control functions and a serial interface for command input and debugging output.
A new design for the IPMC was created based on the experience with the first version.
The Atmel XMEGA A1 microcontroller was used in this design. It provides additional
internal I2 C interfaces. This allowed for the reduction of the number if ICs used on the
board, leading to a board size of only 62 mm × 25.5 mm. PCBs for the new version
were ordered, and a first prototype was produced. Figure ?? shows a photograph of the
new IPMC plugged into a Compute Node. Parts of the firmware that was written for
the first IPMC version were already successfully ported to the new microcontroller. The
development of the firmware is still ongoing, in order to make the controller compliant
with the AdvancedTCA specification.
Bes III
The BESIII experiment is located at the BEPC II collider in Beijing, China at the Institute
for High Energy Physics, commonly known as IHEP. It’s an symmetric e+ e− experiment
optimized for the investigation of τ and charm physics.
Since 2009, BESIII has taken over 220M J/Ψ, 106M Ψ(2S), about 1f b−1 Ψ(3770) events
and more charmonium data will be collected in the next few years.
We have currently three ongoing analyses in our group. The study of N* resonances
via charmonium decays is very promising since the initial state Ψ(2S) has isospin zero.
35
Yields
Isospin is conserved in hadronic decays, thus the final state pp̄π 0 decays exclusively via
intermediate N* resonances. This simplifies partial wave analysis due to the absence of
additional resonances with isospin 3/2. A related program on excited hyperon states has
been started.
Furthermore, the analysis of the branching ratio of Ψ(3770) → pp̄ is in progress. Here, the
goal is to obtain an estimate for the unknown cross section for open charm production at
PANDA.
Fig.8 shows the invariant mass distribution of pp̄ pairs using a subset of the Ψ(3770) data.
After subtracting the non-resonant contribution, the branching ratio of Ψ(3770) → pp̄ can
be determined.
50
40
30
20
10
0
3.2
3.4
3.6
3.8
4
Mpp(GeV/c2)
Figure 8: Invariant mass distribution of pp̄ pairs from 1f b−1 data taken at the Ψ(3770)
resonance .
As the time-reversed process, the cross section of pp̄ → Ψ(3770) can be calculated according to detailed balance. This cross section could be used to estimate a lower limit for the
cross section of pp̄ to open charm which is important for the open charm physics program
at PANDA.
Belle
In June 2010, the Belle experiment stopped data acquisition for preparations for the
future experiment Belle II to be taken place. In total 1024 fb−1 of data were collected,
where beam energies at the Υ(4s) resonance account for 711 fb−1 . The additional
data were collected at beam energies corresponding to the Υ(5S) (121 fb−1 ), Υ(3S) (3
fb−1 ),Υ(2S) (24 fb−1 ), andΥ(1S) (5.7 fb−1 ). The missing part of the data is off-resonance
data.
In 2010 different data analysis projects were performed in Prof. Dr. Kühns group.
One focus was given to the identification of Υ(5S)’ decay modes, which in contrast to
36
Υ(4S) (→ Bu,d Bu,d dominantly) can decay into various finale states containing Bu,d , Bs ,
excited B mesons, . . . . The huge amount of decay modes do not allow a straight forward
identification of the B mesons the resonance was decaying into. Thus, the applicability
of self-organizing neural networks in order to distinguish between the dominating decay
modes of the Υ(5S) resonance has been examined.
The investigation’s conclusion is that a clear identification of the individual is not possible
using neural networks only. However, the number of B mesons can be increased by a
factor of about 1.6 in data sets utilizing the technique.
Another research topic concerned the X(3872) resonance: since it’s nature has not
been unambigiously clarified, a search for a bottom counter particle Xb decaying into
B (∗) B̄ (∗) (π)(π) has been performed. Data from an energy scan between Υ(4S) and
Υ(6S) energies were used to search for leptons from semileptonically decaying B mesons,
the lepton yield from such decays is then a measure of the B meson production. An
√
investigation of the luminosity normalized B meson yield as a function of s could reveal
such new states as the Xb . At Υ(5S) energy an enhancement of B meson production can
be observed, furthermore preliminary evidence for B meson production in Υ(6S) decays
has been found.
Figure 9: The normalized dilepton yield√including correction factor as a function of s.
The datapoints below the B 0 B̄ 0 threshold
correspond to continuum dilepton yield from
Υ(1S), Υ(2S), Υ(3S) and off-resonance data
(no correction factor applied).
Figure 10: Same as Fig.1, but zoomed into
the Υ(5S, 6S) region: The upper plot shows
the normalized dilepton yield including
the
√
correction factor as a function of s. The
lower plot shows the corresponding Υ(5S)
and Υ(6S) lineshapes measured in inclusive
hadron production by Belle [1].
37
[1] K.-F. Chen et al.,
Observation of an enhancement in e+ e− → Υ(1S)π + π − , Υ(2S)π + π − , and Υ(3S)π + π −
√
production near
s = 10.89 GeV, Phys.
Rev.
D82, 091106(R) (2010), hepex/0810.3829v1
Belle II
In 2010, work on the data readout and reduction system for the Belle II DEPFET pixel
detector started in our group. Due to the high luminosity and small distance to the
interaction region a high data rate of ≤22 Gbytes/s is expected for a trigger rate of
≤30 kHz and an estimated pixel detector occupancy of ≤3% [1]. This is by far exceeding
the specifications of the Belle II event builder system. Therefore, a data reduction is
mandatory. For the data readout and reduction an ATCA shelf with 14 Compute Nodes
(CN) is foreseen.
A reduction factor of five is expected in the event rate by the High Level Trigger (HLT)
decision. As the HLT decision arrives out of order and with a latency up to 5s, the
challenge is to buffer the full data in the DDR2 memory of the CN until then. For the
accepted events, the HLT provides information on the regions of the pixel detector, where
charged particle tracks are expected. These regions of interest (ROIs) allow for a further
reduction on the event size by a factor of ≃10 by only storing pixel hits correlated with
charged tracks. Additional ROIs could be calculated on the CN for low pT tracks by
cluster finding or by using information from the silicon strip vertex detector. Work has
been started on software and hardware implementation including the data transfer, the
buffering algorithm and the ROI core. A full featured Linux system including remote
secure shell access as well as a full gcc compiler suite allows for direct development
of the software part on the embedded PowerPC. Controlling the IP cores by memory
mapped hardware registers proved to be extremely useful for debugging the hardware
implemented algorithms as result can be compared directly to the expected behavior. A
test bench system using an additional Linux PC which send data by ethernet to the CN
and receives the processed data is used as a base for a complete prototype system which
is expected to be finished in spring 2011.
[1] T. Abe et al., Belle II Technical Design Report,
arXiv:1011.0352v1 [physics.ins-det]
Cluster installation
In early 2010 our work group acquired a High Performance Computing (HPC) cluster.
Since then it has been used for simulation and data analysis mostly for the BES, PANDA
and Belle experiments. From the careful selection and the physical installation of the
hardware to the software installation, all steps were carried out by members of our work
group.
38
The total computing power of the cluster amounts to 18 Intel Xeon E5520 Quad-Core
CPUs that can run 144 threads in parallel with 108 GB of DDR3 ECC RAM, distributed
over 9 servers, all connected by multiple 1 GBit ethernet lanes. The cluster’s main storage
is provided by an external RAID system that has been equipped with 24 disks of 2 TB
capacity in a RAID 5 array with one hot spare amounting to a net capacity of 44 TB.
The cluster is physically located in Serverraum 2 of the Hochschulrechenzentrum and it is
mapped into our work group’s subnet.
All cluster servers run Scientific Linux CERN (SLC) 5.5 x86 64. A combination of Torque
and Maui is used to distribute jobs on all servers and to use the available computing
power in the most efficient way. The user home directories are backed up on tape on
a daily basis by a service provided by the Hochschulrechenzentrum. The cluster’s state
can be monitored live over the internet with the installed Ganglia monitoring system. A
screenshot is shown in fig. 11.
Further details can be found in [1].
Figure 11: A view on the cluster’s load with Ganglia after it has just finished the simulation
of 2 · 106 background events for a PandaRoot simulation of the decay of X(3872).
[1] M. Galuska, T. Gessler, The Computing Cluster
39
1. Björn Spruck
First Results of BES-III
Giessen HIC4FAIR Kolloquium, 4.2.2010
Publications
1. FPGA-based Adaptive Computing Architecture for Correlated Multistream Processing
Ming Liu, Zhonghai Lu, Wolfgang Kuehn, and Axel Jantsch
In Proceedings of the Design, Automation & Test in Europe conference 2010
(DATE’10), Dresden, Germany, Mar. 2010.
2. Origin of the low-mass electron pair excess in light nucleus-nucleus collisions.
G. Agakishiev et al.
Phys.Lett.B690:118-122,2010 e-Print: arXiv:0910.5875Â [nucl-ex]
3. In-Medium Effects on K0 Mesons in Relativistic Heavy-Ion Collisions.
Phys.Rev.C82:044907 (2010) e-Print: arXiv:1004.3881Â [nucl-ex]
4. Lambda-p femtoscopy in collisions of Ar+KCl at 1.76 AGeV.
Phys. Rev. C 82, 021901 (2010) e-Print: arXiv:1004.2328Â [nucl-ex]
5. Investigating dense nuclear matter with electromagnetic and rare
hadronic probes
M. Lorenz for the HADES collaboration
XLVIII International Winter Meeting on Nuclear Physics in Memoriam of Ileana
Iori
6. Omega and eta meson production in p+p reactions at Ekin = 3.5 GeV.
K. Teilab et al.
To appear in the proceedings of 11th International Workshop on Meson Production,
Properties and Interaction (MESON 2010), Cracow, Poland, 10-15 Jun 2010.
e-Print: arXiv:1009.3442Â [nucl-ex]
7. Performance of the Low-Jitter High-Gain/Bandwidth Front-End Electronics of the HADES tRPC Wall
D. Belver at al.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 57, NO. 5, OCTOBER
2010
8. RPC HADES-TOF wall cosmic ray test performance
A. Blanco at al.
40
Nucl. Instr. and Meth. A (2010), doi:10.1016/j.nima.2010.08.068] X Workshop on
Resistive Plate Chambers and related Detectors - RPC-2010, February 9-12, 2010,
GSI, Darmstadt
9. Study of the Lambda(1405) Resonance in p+p at 3.5GeV
L. Fabbietti
Nuclear Physics A 835 (2010) 333 The 10th International Conference on NucleusNucleus Collisions (NN2009), Beijing, China, 16-21 August 2009
10. The slow control system of the HADES RPC wall
A. Gil at al.
Nucl. Instr. and Meth. A (2010), doi:10.1016/j.nima.2010.08.033
11. Dilepton Production SIS Energies Studied with HADES
R. Holzmann for the HADES collaboration
Nuclear Physics A 834 (2010) 298c The 10th International Conference on NucleusNucleus Collisions (NN2009), Beijing, China, 16-21 August 2009
12. Dielectron production in Ar+KCl collisions at E(kin) = 1.76-AGeV.
M. Jurkovic at al.
PoS BORMIO2010:051,2010. 48th International Winter Meeting On Nuclear
Physics, 25-29 Jan 2010, Bormio, Italy
13. Studying hadron properties in baryonic matter with HADES.
A.Kugler et al.
AIP Conf.Proc.1257:691-694,2010. Hadron 2009: 13th International Conference On
Hadron Spectroscopy, 29 Nov - 4 Dec 2009, Tallahassee, Florida
14. Investigation of the production of electron-positron pairs in nucleonnucleon interactions with the HADES detector
K. Lapidus for the HADES collaboration
Phys.Atom.Nucl.73:985-987,2010, Yad.Fiz.73:1021-1023,2010.
15. Strangeness Production at SIS measured with HADES
J. Pietraszko for the HADES collaboration
Nuclear Physics A 834 (2010) 288c The 10th International Conference on NucleusNucleus Collisions (NN2009), Beijing, China, 16-21 August 2009
16. Diamonds as timing detectors for minimum-ionizing particles: The
HADES proton-beam monitor and START signal detectors for time of
flight measurements
J. Pietraszko et al.
Nuclear Instruments and Methods in Physics Research A 618 (2010) 121-123
17. Study of electromagnetic processes with the dielectron spectrometer
HADES.
B. Ramstein et al.
41
AIP Conf.Proc. 1257 (2010) 695-699 Hadron 2009: 13th International Conference
On Hadron Spectroscopy, 29 Nov - 4 Dec 2009, Tallahassee, Florida
18. Study of elementary reactions with the HADES dielectron spectrometer
B. Ramstein et al.
Acta Phys.Polon.B41:365-378,2010. Mazurian Lakes Conference on Physics, Piaski,
Poland, August 30 - September 6, 2009
19. Inclusive meson production in 3.5-GeV p p collisions studied with the
HADES spectrometer.
A. Rustamov et al.
AIP Conf.Proc. 1257 (2010) 736-740 Hadron 2009: 13th International Conference
On Hadron Spectroscopy, 29 Nov - 4 Dec 2009, Tallahassee, Florida
20. Strangeness measurements at the HADES experiment.
A. Schmah for the HADES collaboration
J.Phys.G G37 (2010) 094004 International Conference On Strangeness In Quark
Matter 2009 (SQM 2009), 27 Sep - 2 Oct 2009, Buzios, Brazil
21. Omega and eta meson production in p+p reactions at Ekin = 3.5 GeV.
K. Teilab et al.
11th International Workshop on Meson Production, Properties and Interaction,
Krakow, Poland, 10 - 15 June 2010
22. Future experiments with HADES at FAIR.
HADES Collaboration (P. Tlusty (Rez, Nucl. Phys. Inst.) for the collaboration).
2010. 9 pp.
Published in AIP Conf.Proc. 1322 (2010) 116-124
23. Analysis techniques for the Lambda(1405) in p+p reactions.
HADES Collaboration (Johannes Siebenson (Muenchen, Tech. U. Universe) for the
collaboration). 2010. 5 pp.
24. Probing resonance matter with virtual photons.
HADES Collaboration (Tetyana Galatyuk for the collaboration). Nov 2010. 10 pp.
e-Print: arXiv:1011.5424 [nucl-ex]
25. Study of electromagnetic processes with the dielectron spectrometer
HADES.
HADES Collaboration (B. Ramstein (Orsay, IPN) for the collaboration). 2010. 5
pp.
26. Measurement of the Λ(1405) in proton proton reactions with HADES.
HADES Collaboration (Johannes Siebenson et al.). Sep 2010. 5 pp.
Published in PoS BORMIO2010 (2010) 052
42
27. Investigation of the production of electron-positron pairs in nucleonnucleon interactions with the HADES detector.
HADES Collaboration (K.O. Lapidus (Moscow, INR) for the collaboration). 2010.
3 pp.
Published in Phys.Atom.Nucl. 73 (2010) 985-987
28. Hadron Physics with Strange and Charm Quarks - the PANDA Experiment
Olaf N. Hartmann et al.
10th International Conference on Heavy Quarks and Leptons 11. OCT. 2010 - 15.
OCT. 2010, Laboratori Nazionali di Frascati dell’INFN
29. Time-like Electromagnetic Form Factors
J. Boucher, T. Hennino, R. Kunne, D. Marchand, S. Ong, B. Ramstein, M. Sudol,
E. Tomasi-Gustafsson, J. Van de Wiele (IPN Orsay)
XX Int. Baldin Seminar on High Energy Physics Problems 04. OCT. 2010 - 04.
OCT. 2010, Dubna(Russia)
30. Feasibility studies of the time-like proton electromagnetic form factor
measurements with PANDA at FAIR.
M. Sudol, et al.
The European Physical Journal A - Hadrons and Nuclei, Volume 44, Number 3,
373-384, DOI: 10.1140/epja/i2010-10960-8
31. Strong Interaction Physics with PANDA
Albrecht Gillitzer (FZ Juelich)
International Journal of Modern Physics A, Volume 26, Issue 03-04, pp. 523-528
(2011) MESON 2010 Conference
10. JUN. 2010 - 15. JUN. 2010, Cracow
32. Prospects for X(3872) Detection at Panda
Sören Lange (Universität Giessen)
MENU2010 conference, 05/31-06/04/2010 02.
arXiv:1010.2350v2 [hep-ex]
(∗)+
JUN.
2010,
e-Print:
(∗)−
33. Measurement of e+ e− →Ds Ds
cross sections near threshold using
initial-state radiation.
Belle Collaboration (G. Pakhlova et al.)
Phys.Rev.D83:011101,2011 arXiv:1011.4397 [hep-ex]
34. Search for charmonium and charmonium-like states in Υ(1S) radiative
decays.
By Belle Collaboration (C.P. Shen et al.)
Phys.Rev.D82:051504,2010. arXiv:1008.1774 [hep-ex]
35. Measurement of ηη production in two-photon collisions.
43
Belle Collaboration (S. Uehara et al.)
(∗)+
(∗)−
36. Observation of Bs0 →Ds Ds
using e+ e− collisions and a determination
of the Bs B s width difference ∆Γs .
Belle Collaboration (S. Esen et al.)
Phys.Rev.Lett.105:201802,2010 arXiv:1005.5177 [hep-ex]
37. Search for a Low Mass Particle Decaying into µ+ µ− in B 0 →K ∗0 X and
B 0 →ρ0 X at Belle
Belle Collaboration (H.J. Hyun et al.)
38. Measurement of Y (5S) decays to B 0 and B + mesons.
Belle Collaboration (A. Drutskoy et al.)
(∗)−
39. Observation of Bs0 →Ds∗− π + , Bs0 →Ds ρ+ Decays and Measurement of
Bs0 →Ds∗− ρ+ Polarization.
Belle Collaboration (R. Louvot et al.)
40. Study of the B→X(3872)(→D ∗0 D 0 )K decay.
Belle Collaboration (T. Aushev et al.)
Phys.Rev.D81:031103,2010.
41. Evidence for direct CP violation in the decay B→D (∗) K, D→Ks π + π − and
measurement of the CKM phase φ3 .
Belle Collaboration (A. Poluektov et al.)
42. Search for leptonic decays of D 0 mesons.
Belle Collaboration (M. Petric et al.)
43. Search for Lepton Flavor Violating τ Decays into Three Leptons with 719
Million Produced τ + τ − Pairs.
Belle Collaboration (K. Hayasaka et al.)
Phys.Lett.B687:139-143,2010. arXiv:1001.3221 [hep-ex]
+
+
44. Search for CP violation in the decays D(s)
→KS0 π + and D(s)
→KS0 K + .
Belle collaboration (B.R. Ko et al.)
Phys.Rev.Lett.104:181602,2010. arXiv:1001.3202 [hep-ex]
44
45. Confirmation of the X(1835) and Observation of the Resonances X(2120)
′
and X(2370) in J/Ψ → γπ + π − η .
M. Ablikim et al. (BESIII Collaboration)
Phys. Rev. Lett.106, 072002 (2011).
46. First observation of the decays χcJ → π 0 π 0 π 0 π 0 .
Phys. Rev. D 83, 012006 (2011)
′
47. Measurement of the matrix element for the decay η → ηπ + π − .
Phys. Rev. D 83, 012003 (2011).
′
48. Evidence for Ψ Decays into γπ 0 and γη.
Phys. Rev. Lett. 105, 261801 (2010).
′
49. Measurements of hc (1 P1 ) in Ψ Decays.
Phys. Rev. Lett. 104, 132002 (2010).
50. Branching fraction measurements of χc0 and χc2 to π 0 π 0 and ηη.
Phys. Rev. D 81, 052005 (2010).
′
51. Observation of a pp̄ mass threshold enhancement in Ψ → π + π − J/Ψ(J/Ψ →
γpp̄) decay.
Chinese Physics C 34,4(2010).
1. Bormio, Italy: 25.1.-29.1.2010, XLVIII International Winter Meeting on
Nuclear Physics
Qiang Wang et al.
PANDA EMC Trigger and Data Acquisition Algorithm Development
2. Dresden, 8.3.-12.3.2010, Design, Automation & Test in Europe conference 2010
Ming Liu, Zhonghai Lu, Wolfgang Kühn and Axel Jantsch
FPGA-based Adaptive Computing Architecture for Correlated Multi-stream Processing
45
3. Darmstadt GSI, Panda Meeting, 10.03.2010
Martin Galuska
Simulation of X(3872) Decays Using the PandaRoot Framework
4. Bonn, 15.3.-19.3.2010, DPG Tagung
Ingo Heller et al.
Inclusive hadron spectroscopy in J/Ψ and Ψ(2S)
Martin Galuska et al.
Simulation of X(3872) Decays Using the PandaRoot Framework
Qiang Wang et al.
Development of High Level Trigger for PANDA EMC Using an FPGA-based
Compute Node
Ming Liu et al.
FPGA-based Adaptive Computing for Online Trigger Algorithms
David Münchow et al.
An FPGA helix tracking algorithm for PANDA
Björn Spruck et al.
Measurement of Hyperon Decays of Charmonia with the BESIII Detector
Yutie Liang
Study of decays of Ψ(3770) and Ψ(2S) into pp related channels
5. Karlsruhe, 16.-20.5.2010 International Workshop on Reconfigurable Communication Centric System-on-Chips (ReCoSoC’10)
Reducing FPGA Reconfiguration Time Overhead using Virtual Configurations
6. Lissabon, 24.-28.5.2010, 17th Real Time Conference, RT10
David Müchow, Qiang Wang, Dapeng Jin, Andreas Kopp, Wolfgang Kühn, Sören
Jens Lange, Yutie Liang, Ming Liu, Zhen-an Liu, Björn Spruck, Hao Xu
Developments for the PANDA Online High Level Trigger
7. Williamsburg, USA, 31.5.-4.6.2010, 12th Int. Conference on MesonNucleon Physics and the Structure of the Nucleon
Sören Lange
Prospects for X (3872) Detection at Panda
8. Shenyang, China, The BESIII Collaboration Summer 2010 Meeting, 3.7.6.2010
Yutie Liang
Study of Ψ(3770) decays into pp related channel
9. Stockholm, PANDA XXXIII Collaboration Meeting, 14. -18.6.2010
Björn Spruck
EvtGen inside the PandaRoot Framework
Adding full MC Event Decay Tree to File
Yutie Liang
Software of Disc DIRC in PandaRoot
46
10. Kefalonia, Greece, 3.7.-15.7.2010. Symposium on VLSI (ISVLSI’10),
Lixouri
Inter-Process Communications using Pipes in FPGA-based Adaptive Computing
11. Peking, BESIII Software/Physics Workshop, 25.-27.2.2010
Yutie Liang
Study of Ψ′ → p pφ
12. Rauischholzhausen, PANDA DAQT and FrontEnd Electronics Workshop,
15.04.2010
David Münchow
13. PANDA DAQT and FrontEnd Electronics Workshop Rauischholzhausen,
15.04.2010
Thomas Gessler
An IPM Controller for the PANDA Compute Node
14. Grünberg Belle-II PXD DAQ/Trigger Workshop, 24.- 26.09.2010
David Münchow
Helix Tracking Algorithm for PANDA
15. BESIII Collaboration 2010 Fall Meeting 25.-28.10.2010
Yutie Liang
PWA of Ψ(2S)→ppπ 0
47
48
Group of Prof. Dr. V. Metag
Sekretariat:
A. Rühl
Academic
Prof. Dr. V. Metag
Dr. R. Novotny (AkDir)
Dr. H. Berghäuser (since 10/10)
Dr. P. Drexler
Dr. V. Dormenev
Dr. M. Nanova
Technical support:
W. Döring (PTA) (until 6/10)
R. Schubert
PhD Students:
H. Berghäuser (until 9/10)
D. Bremer (since 4/10)
F. Dietz (born Hjelm)
T. Eißner
S. Friedrich
B. Lemmer (until 3/10)
K. Makonyi
M. Moritz
M. Thiel
Diploma Students:
D. Bremer (until 3/10)
Bachelor Students:
S. Diehl
W. Lippert
D Mühlheim
49
Measurement of the η- transition form factor in the γp → pη → pγe+ e−
reaction
The Dalitz decay η → γe+ e− has been measured using the combined Crystal Ball
and TAPS photon detector9 setup at the electron accelerator MAMI-C. Compared
to the most recent transition form factor measurement in the e+ e− channel by the
SND collaboration [1], statistics have been improved by one order of magnitude. The
e+ e− invariant mass distribution shows a deviation from the QED prediction for a
point-like particle, which can be described by a form factor (see Fig.12). Using the usual
monopole transition form factor parameterization, F (m2 ) = (1 − m2 /Λ2 )−1 , a value of
Λ−2 = (1.92 ± 0.35(stat) ± 0.1(syst)) GeV−2 has been determined. This value is in good
agreement with a recent measurement of the η Dalitz decay in the µ+ µ− channel [2]
and with recent form factor calculations [3,4]. An improved value of the branching ratio
BR(η → γe+ e− = (6.6 ± 0.4) · 10−3 has been determined compared to the current PDG
value of (7.0 ± 0.7) · 10−3 .
[1] M. N. Achasov et al., Phys. Lett. B 504 (2001) 275.
[2] R. Arnaldi et al., Phys. Lett. B 677 (2009) 260.
[3] C. Terschlüsen and S. Leupold, Phys. Lett. B 691 (2010) 191.
[4] C. Terschlüsen, Diploma Thesis, Univ. of Giessen, 2010,
http://www.uni-giessen.de/cms/fbz/fb07/fachgebiete/physik/einrichtungen/
theorie/theorie1/publications/diploma.
Search for ω-mesic states in Boron
Our search for nuclear-mesic states is performed using the tagged photon beam facility at
the ELSA accelerator in Bonn. The combined setup of the Crystal Barrel and MiniTAPS
detector systems, which form a 4π electromagnetic calorimeter, are used for identifying
the decaying mesons. The aim of the project is to clarify the existence of ω-bound
states in Boron nuclei using different approaches like recoilless production as well as
back-to-back emission of decay products. Two beamtimes with Carbon as target material
were performed and in addition a hydrogen run as a reference to reduce systematic errors
in the analysis of the Carbon data.
The existing GEANT3 simulation program provides information about the detector
response, detecting efficiencies and background contributions. A simulation tool for
understanding the physics of the background channels and elementary reactions is given
by a Boltzmann-Uehling-Uhlenbeck transport model of the Giessen theory group called
GiBUU [1]. Using GiBUU simulations as an event generator for the GEANT3 framework
information on the contributing background channels is obtained. A signature for the
existence of an ω-bound state would be a structure in the kinetic energy distribution of
the ω-meson at negative energies as well as an additional structure in the π 0 γ invariant
mass distribution.
50
|Fη(q ;0;mη2)|2
QED
Fit to CB/TAPS-Data
CB/TAPS MAMI-C
2
NA60
SND
Terschluesen Leupold
1
0
100 200 300 400 500
Masse+e- [MeV]
Figure 12: η-Dalitz transition form factor: The red squares are the data of this work (the
black curve is the fit to the data). The green (open) circles show the result of the SND
experiment [1]. The inverted (blue) triangles represent the result obtained by NA60 [2] in
the µ+ µ− channel. The green (dashed) curve is a calculation performed by [4].
51
Figure 13: Comparison between data (top) and GiBUU simulations (bottom):
Kinetic energy of the ω-mesons (left side) and π 0 γ invariant mass spectra (right side) with
background contribution for momenta pω < 300 MeV/c
Figure 13 shows a simultaneous fit of the kinetic energy and invariant mass distributions
by a background distribution from π 0 π 0 production (blue dashed line) and a signal (red
dashed line). It cannot reproduce the data for momenta pω < 300 MeV/c (top). However,
the same fitting method does reproduce the distributions from GiBUU simulations where
all known contributing channels are simulated (bottom).
[1] http://gibuu.physik.uni-giessen.de/GiBUU/
In-medium properties of ω mesons in photonuclear reactions
The search for mass shifts in the lineshape of hadrons has turned out to be more
52
counts / (9 MeV/c2)
LH2: σ = 28.1 ± 0.6 MeV
τ = -0.09 ± 0.02
Nb: σ = 29.1 ± 2.8 MeV
τ = -0.29 ± 0.16
LH2
Nb
MC
1.2
100
50
0
600
b)
1
dσ/Mπγ [normalized to max.]
a)
150
vac. SF
CB
CB + shift
shift
data
0.8
0.6
0.4
0.2
0
650
700
750
800
Mπγ [MeV/c2]
850
900
-0.2
600
650
700
750
800
Mπγ [MeV/c2]
850
900
Figure 14: a) ω signal (solid points) for the N b target and incident photon energies from 900 - 1300
MeV. A fit curve to the data points (see text) is shown in comparison to the ω lineshape measured
on a LH2 target and a Monte Carlo simulation; b) ω signal for the N b target in comparison to
recent GiBUU simulations for the following scenarios: no medium modification (solid), in-medium
broadening of Γcoll = 140 MeV at nuclear saturation density (long dashed), an additional mass
shift by -16% (short dashed), mass shift without broadening (dotted). The signals are folded with
the detector response
complicated than initially thought at least in the case of a strong broadening of the
meson [1]. As pointed out in [2], the measured mass distribution in experiments with
elementary probes represents a convolution of the hadron spectral function with the
branching ratio ΓH→X1 X2 /Γtot (m) into the channel being studied. As a consequence,
for a strong in-medium broadening of the hadron (increasing Γtot ) - as observed for the
ω-meson [3] - the in-medium signal is suppressed by the factor Γω→π0 γ /Γtot and the
strength of the in-medium signal is spread out in mass so strongly that it becomes hard
to distinguish it from the background [2]. Also the relatively long lifetime of the ω-meson
affects the sensitivity to in-medium modifications. Only about 20% of all ω → π 0 γ decays
in N b occur at densities ρ/ρ0 > 0.1 for the given reaction kinematics according to BUU
simulations [4] even requiring the ω recoil momentum to be lower than 500 MeV/c. In
addition, due to inelastic processes like ωN → πN , ω-mesons are removed in the nuclear
medium thereby reducing their effective lifetime and correspondingly increasing their
width.
A significant in-medium effect has, however, been predicted by the GiBUU model [5]
close to the ω production threshold of Eγ =1109 MeV. For an ω analysis in the threshold
region a cut on the incident photon energy from 900 to 1300 MeV was applied. The
analysis went through the same steps as described in detail in [1]. For this energy range
the cut on the ω momentum is not applied. A fit to the data is compared to the ω signal
53
measured on the LH2 target and to a Monte Carlo simulation of the ω signal in Fig. 14a.
A slight deviation from the reference signal on LH2 and the simulation is observed. In
view of the systematic and statistical uncertainties, however, no significant deviation from
the reference signals is claimed. Higher statistics will be needed to draw any conclusion.
In Fig 14b the measured ω signal is compared to predictions of recent GiBUU transport
calculation [6] for different scenarios. While all the curves seem to underestimate the
data slightly on the low mass side of the ω peak, the experimental data obviously do not
allow to distinguish between the various theoretical scenarios.
[1] M. Nanova et al., CBELSA/TAPS Collaboration, Phys. Rev. C 82, 035209 (2010).
[2] S. Leopold, V. Metag and U. Mosel, Int. J. Mod.Phys. E 19, 147 (2010).
[3] M. Kotulla et al., Phys. Rev. Lett. 100, 192302 (2008).
[4] P. Mühlich, Dissertation, Giessen University, (2007).
[5] K. Gallmeister, M. Kaskulov, U. Mosel, and P. Muehlich, Prog. Part. Nucl. Phys.
61, 283 (2008).
[6] M. Nanova et al., CBELSA/TAPS Collaboration, Eur. Phys. J. A 47, 16 (2011).
In-medium properties of the ω meson near the production threshold
Using the CB/TAPS photon spectrometer at MAMI Mainz the ω photoproduction off
nuclei (C, Nb) and off the proton (LH2 ) were studied via the hadronic decay channel
ω → π 0 γ in the energy range 900 to 1300 MeV. Two different experimental approaches are
used: the measurement of the lineshape and of the momentum distribution. Performing
the lineshape analysis, the background has to be determined and subtracted. Therefore
a fit and a description directly from the data [1] are used. The comparison of the
experimental observed results to GiBUU calculations [2] performed by J. Weil does not
allow to favour a specific in-medium scenario since the sensitivity is limited due to the
strong broadening of the meson in the medium. Only the scenario including mass shift
only seems to be disfavoured (figure 15, left panel). This is supported by the results from
the analysis of the momentum distribution. Here the ω yield is determined in several
momentum bins (each 50 MeV/c) and again compared to GiBUU calculations (figure 15,
right panel).
[1] M. Nanova et al., CBELSA/TAPS collaboration, Phys. Rev. C 82, 035209 (2010)
[2] http://gibuu.physik.uni-giessen.de
Developments and preparations for the PANDA-EMC
Several major steps have been performed to prepare the final design of the electromagnetic calorimeter (EMC) of the target spectrometer of PANDA. The main activities
have focused on the quality control of the delivered PWO crystals, detailed studies on
the recovery of radiation damage and the analysis of measurements of the response
54
Figure 15: The lineshape of the niobium data (left panel) and the momentum distribution
(right panel) for the two targets carbon (purple points) and niobium (open black circles)
are compared to the theoretical GiBUU predictions: vacuum (solid red line), collisional
broadening (dashed green line), collisional broadening plus mass shift (dashed blue line)
and mass shift only (dotted magenta line).
to high-energy photons using prototype detectors. The quality control as well as the
detailed analysis of all 7355 PWO-II crystals, delivered by the manufacturer BTCP
in Russia, was completed. Only 458 crystals had to be rejected corresponding to a
fraction of 6.2% and confirms the excellent performance. The very selective limit on
radiation hardness was the primary reason for rejection (85%). The final operation of the
calorimeter at the low temperature of T = −25◦ C requires extremely high radiation resistivity of the crystals since thermo-activated recovery processes are drastically slowed down.
One can overcome or at least significantly compensate the damage by the recently
discovered new effect of stimulated recovery [1]. It turned out that exposing the
crystal to external light up to the infrared region of 1300nm could recover the optical
transparency within a short period. The mechanism has been confirmed as well at low
temperatures but leading to longer recovery times. As illustrated in Fig. 1 the mechanism
can be applied even on-line if the chosen photo sensor is blind for the external light source.
In close collaboration with the groups at KVI (Groningen) and Orsay, respectively,
response measurements of the barrel prototype PROTO60 have been continued and
analysed. The energy, position and in particular time resolutions have been confirmed and
55
Figure 16: Spectral ranges of the applied LED light sources for successfully stimulated
recovery in comparison to the distributions of the luminescence of PWO and the quantum
efficiencies of a bialkali photo cathode or an avalanche photo diode, respectively
even improved by the digitization of the signals with a sampling ADC. Additional tests
simulating the impact of the Barrel DIRC and dead material on the energy resolution
have been performed and indicate significant deterioration at energies below 200MeV.
In addition, the assembly of a new significantly improved detector matrix comprising
6x6 crystals and implementing for the first time the read-out of each crystal with two
rectangular LAAPDs via the pre-amplifier ASIC APFEL has been started.
[1] V. Dormenev et al., Nucl. Instr. and Meth. in Phys. Res. A 623 (2010) 1082-1085.
56
1. R. W. Novotny
The PANDA electromagnetic Calorimeter – a high-resolution detector based on
PWO
CERN Detector Seminar, CERN, Geneva, Switzerland, 21.01.2010
Publications
1. The search for in-medium modifications of mesons - experimental status
V. Metag
AIP Conf. Proc. 1322 (2010) 73
doi:10.1063/1.3541969
2. Modification of the ω meson properties in the nuclear medium
M. Nanova
AIP Conf. Proc. 1322 (2010) 108
doi:10.1063/1.3541969
3. In-medium ω mass from the γ + N b → π 0 γ + X reaction
M. Nanova, V. Metag, G. Anton, J.C.S. Bacelar, O. Bartholomy , D. Bayadilov,
Y.A. Beloglazov, R. Bogendörfer, R. Castelijns, V. Crede, H. Dutz, A. Ehmanns,
D. Elsner, K. Essig, R. Ewald, I. Fabry, M. Fuchs, Ch. Funke, R. Gothe, R. Gregor, A.B. Gridnev, E. Gutz, S. Höffgen, P. Hoffmeister, I. Horn, J. Hössl, I. Jaegle,
J. Junkersfeld, H. Kalinowsky, Frank Klein, Friedrich Klein, E. Klempt, M. Konrad,
B. Kopf, M. Kotulla, B. Krusche, J. Langheinrich, H. Löhner, I.V. Lopatin, J. Lotz,
S. Lugert, D. Menze, T. Mertens, J.G. Messchendorp, C. Morales, R. Novotny,
M. Ostrick, L.M. Pant, H. van Pee, M. Pfeiffer, A. Roy, A. Radkov, S. Schadmand,
Ch. Schmidt, H. Schmieden, B. Schoch, S. Shende, G. Suft, A. Süle, V. V. Sumachev,
T. Szczepanek , U. Thoma, D. Trnka, R. Varma, D. Walther, Ch. Weinheimer,
Ch. Wendel
Phys. Rev. C 82 (2010) 035209
arXiv:1005.5694 [nucl-ex]
http://arxiv.org/abs/1005.569
4. Vector mesons in strongly interacting matter
V. Metag
Pramana 75 (2010) 195
5. In-medium modifications of the ω meson
M. Nanova
AIP Conf. Proc. 1257 (2010) 705
doi:10.1063/1.3483425
6. Hadrons in strongly interacting matter
S. Leupold, V. Metag, and U. Mosel
Int. J. Mod. Phys. E 19 (2010) 147
57
arXiv:0907.2388 [nucl-th]
http://arxiv.org/abs/0907.2388
7. Stimulated recovery of the optical transmission of PbWO4 crystals for
electromagnetic calorimeters after radiation damage
V. Dormenev, T. Kuske, R. W. Novotny, A. Borisevich, A. Fedorov, M. Korjik, V.
Mechinski, O. Missevitch, S. Lugert
Nucl. Instr. and Meth. in Phys. Res. A 623 (2010) 1082-1085
8. Inorganic Scintillators – A Never Ending Story
R. W. Novotny
Nuclear Physics News, Vol. 20 (2010) 27-30
1. BARYONS’10 ”International Conference on the Structure of Baryons”,
Osaka, Japan (Dez. 2010)
M. Nanova
′
In-medium properties of ω and η mesons in elementary reactions (invited talk)
2. IEEE Nuclear Science Symposium and Medical Imaging Conference,
Knoxville, Tennessee, USA, October 30 – November 6, 2010
A. E. Borisevitch et al.
Maintaining low radiation damage of lead tungstate scintillation crystals operating
in high dose rate radiation environment
3. XIV. International Conference on Calorimetry in High Energy Physics,
IHEP Beijing, China, May 10 – 14, 2010
R. W. Novotny et al.
High-Quality PWO Crystals for the PANDA-EMC
4. Physik der Hadronen und Kerne, Spring Meeting of the German Physics
Society, Bonn (Germany) March 15 – 19, 2010
T. Kuske et al.
Stimulated recovery of radiation damage of PWO-II at −25◦ CC
T. Eissner et al.
Quality Control of Lead Tungstate Crystals for the PANDA-EMC
D. Bremer et al.
Performance of the PROTO60 – Prototype for the PANDA Barrel EMC
M. Thiel
In-medium modifications of the ω meson
5. ECT* workshop ”Electromagnetic Probes of Strongly Interacting Matter”, Trento, Italy (Sept. 2010)
V. Metag
The electromagnetic transition formfactor of the η meson studied in the Dalitz
decay η → e+ e− γ (invited talk)
58
M. Nanova
Photo-excitation of hadrons in nuclei (invited talk)
6. Chiral10 Workshop, Valencia, Spain (June 2010)
V. Metag
The search for in-medium modifications of mesons - experimental status (invited
talk)
M. Nanova
In-medium modifications of the ω meson (invited talk)
7. HIC for FAIR Workshop on Calorimeter technology for HADES at FAIR,
October 14 – 15, 2010
R. W. Novotny
Introduction to Calorimetry
8. Crystal Ball Collaborations meeting, Mainz (March 2010)
M. Thiel
In-medium modifications of the ω meson
59
60
Group of Prof. C. Scheidenberger
Secretariat:
C. Momberger
Academic:
Prof. Dr. C. Scheidenberger
Prof. Dr. Dr. h.c. H. Geissel
Dr. W.R. Plaß
Dr. S. Heinz
Dr. B. Sun
Dr. R. Knöbel
T. Dickel (since 08/2010)
Engineer:
S. Ayet
PhD Students:
T. Dickel (until 07/2010)
F. Farinon
E. Haettner
C. Jesch
N. Kuzminchuk
J. Lang (since 02/2010)
A. Prochazka
B. Riese
Diploma Students:
F. Lautenschläger (until 10/2010)
D. Schäfer (until 04/2010)
T. Schäfer (until 10/2010)
Guests:
Dr. A. Pikhtelev, Chernogolovka, Russia
Prof. Dr. M. Yavor, St. Petersburg, Russia
61
Super-FRS design status report
System and building design. The layout of the Super-FRS was adapted to the Modularized Start Version (MSV) of FAIR. The preliminary planning of the NUSTAR buildings was finished and for the buildings within the MSV the ap-proval planning was started
which covers in particular the shielding design including access labyrinths and media ducts
[1].
Radiation damage. The latest results on radiation damage studies in graph-ite for target
and beam catchers show that ion-induced structural transformation follows different paths
for the energy range dominated by electronic loss and elastic collisions, respectively [2].
The material evolves toward glassy carbon in the first case or towards nanocrystalline
and latter amorphous carbon in the other case. Strong stresses develop at the interface
between irradiated and non-irradiated material. Cracks appear when the highly stressed
interface between beam spot and non-irradiated material is situated in the vicinity of
another stress con-centrator. However, high temperature irradiation experi-ments at the
GSI M-branch with online monitoring of radiation damage show that this effect is reduced
at tem-perature of about 900◦ C and especially at 1500◦ C where the vacancies are highly
mobile [3].
Remote handling and hot cell complex. Due to the high radiation and activation
in the target area and the Pre-Separator of the Super-FRS remote han-dling will be applied for maintenance purpose. The con-cept is based on a vertical plug system which
involves a combination of beam-line inserts (e.g. target, beam-catchers, etc.) with a local mobile shielding that can be removed individually from their vacuum chamber as one
unit (’plug’). The plugs can be transported to a close-by hot cell using a shielded flask.
The plugs will be inserted from the top into the cell. Inside the cell the inserts can be
exchanged using standard handling tools (power manipu-lator, master-slave manipulator,
etc.). Consumables and other activated waste can be packed into standard 200 l barrels
which can be stored temporarily in the storage cell.
Magnets. The prototype of a radiation resistant dipole underwent a complete testing
program for the factory acceptance test at BINP Novosibirsk. The required gap field of
1.6 T could be reached with the nominal current of 640 A. A complete magnetic field map
was measured. After re-machining of the detachable pole end plates the magnet is within
the specified integral homogeneity of ±3 · 10−4 . Long term stability tests, ramping tests
and thermal stabil-ity tests were performed without any problems. Final quench tests
as well as further cold tests of the superconducting dipole magnet developped together
with the FAIR China Group have been performed successfully by IMP in Lanzhou. The
obtained data will be required for the development of the series production of the SC
dipoles magnets for Super-FRS.
[1] A. Plotnikov et al., GSI Scientific Report 2010 (2011) 322.
[2] M. Krause et al., GSI Scientific Report 2010 (2011) 384.
[3] M. Avilov et al., GSI Scientific Report 2010 (2011) 383.
62
Changes of the ashes of an X-ray burst due to better known nuclear
masses
The masses of ten proton-rich nuclides, among them the N =Z+1 nuclides 85 Mo and 87 Tc,
relevant for nucleosynthesis modelling were measured with the Penning trap mass spectrometer SHIPTRAP [1]. Significant deviations in the mass values and separation energies
compared to the values of the Atomic Mass Evaluation 2003 [2] (AME03) were found. The
new experimental mass data were implemented in the Atomic Mass Evaluation and adjusted mass values were obtained following the procedure employed in [3]. Moreover, a new
local (80≤A≤95) mass extrapolation based on the adjusted mass values was made using
the methods and programs of [3]. Together with the new set of evaluated experimental
data and the previously reported AME03 extrapolated mass values for A<80 and A>95
these data form a complete updated mass data set (AMEup).
To explore the impact of the new masses on the rp process in X-ray bursts reaction network
calculations using the model of [4] were carried out. The baseline calculation uses the
nuclear masses of the AME03 and calculated Coulomb mass shifts [5] for nuclides beyond
N =Z. The results are compared to network calculations based on AMEup, combined
with the same Coulomb mass shifts. The resulting final abundances show large differences
between AME03 and AMEup in the region of A=86-96. The largest change is found for
A=86 where the abundance increases by a factor of 20 (Fig. 17) due to an unexpectedly
large decrease in Sp of 87 Tc. This change by a factor of 20 is by far the largest observed for
abundances produced in rp process network calculations since the AME 2003 evaluation.
It demonstrates that nuclear physics uncertainties can be larger than estimated and can
introduce large uncertainties in nucleosynthesis model calculations.
The new results also open up the possibility for the formation of a ZrNb cycle induced by
large 84 Mo(γ,α) or 83 Nb(p,α) reaction rates. For a given Sα value of 84 Mo the cycle will
form at a sufficiently high temperature, effectively providing an upper temperature limit
for any rp process along the proton drip line to produce nuclei beyond A=84, including
9
Overproduction factor
10
8
10
x2
7
10
x20
6
10
5
10
60
70
80
90
100
110
Mass number A
Figure 17: Calculated overproduction factors (produced abundance divided by solar system abundance) after an X-ray burst for the AME03 (dotted line) and the AMEup (solid
line) mass sets.
63
the light p-nuclei in the A=92-98 mass region. In order to explore this temperature
limit, reaction network calculations were performed using a small test network with an
initial 82 Zr abundance. For a Sα of 84 Mo lowered by one standard deviation a significant
cycling was found beginning at 1.5 GK. However, calculations with the full X-ray burst
model, which reaches peak temperatures of 2 GK, show that a cycle does not occur,
because at the required high temperatures the reaction sequence already stops at 56 Ni.
Nucleosynthesis proceeds beyond 56 Ni during burst cooling only when the temperature is
lower than required to form a ZrNb cycle. The formation is nevertheless a possibility in
an environment where the temperature is rising slowly enough to enable the rp process to
proceed past 56 Ni before reaching high temperatures. Another possibility would be an rp
process with seed nuclei beyond 56 Ni.
[1]
[2]
[3]
[4]
[5]
E. Haettner et al., GSI Scientific Report 2008 (2009) 134.
G. Audi et al., Nucl. Phys. A 729, 337 (2003).
A.H. Wapstra et al., Nucl. Phys. A 729, 129 (2003).
H. Schatz et al., Phys. Rev. Lett. 86, 3471 (2001).
B.A. Brown et al., Phys. Rev. C 65, 045802 (2002).
Rate acceptance and new anode design for IMS TOF detector
For Isochronous Mass Spectrometry at the FRS-ESR facility a time-of-flight detector is
used for measurements of the revolution times of stored ions. In the detector, ions passing
a thin carbon foil release secondary electrons (SE), which are transported to microchannel
plates (MCPs) by electric and magnetic fields. Because of the high revolution frequencies
in the ESR, a high rate acceptance is required as well as good timing characteristics.
Rate acceptance. Offline studies show that MCPs with 5 µm pore size can accept a
higher count rate than MCPs with the same active diameter but with a commonly used
pore size of 10 µm [1]. To show the advantages of a 5 µm pore size MCP, the saturation
effects were investigated online with Ne and Ni primary beams in the ESR using carbon
[10 µg/cm2 ] and CsI [17 µg/cm2 ] foils in the time-of-flight detector. Fig. 18 (Left Panel)
shows the average number of ions found per turn for both experimental data and from
model predictions.
To compare the experimental data with simulations a Monte Carlo code is used to calculate
the ion survival probability for a specific number of ions in the ring. The simulations
include the ion optics, apertures in the ESR and the energy loss in the foil.
The dashed blue (10 µm pore size MCPs) / solid red (5 µm pore size MCP) lines represent
the calculations, which combine these Monte Carlo simulations with a model for the dead
time effect. It is known that because of the finite recharging time of an MCP channel
one can observe a saturation effect. This model describes a loss of detection efficiency
at high rates, which also depends on the energy loss in the foil and on the number of
emitted secondary electrons. The number of SE does not change with turn number, but
the detection efficiency of the MCP drops from 60% to about 10% when increasing the
64
100
0.00
Experimental data (10 m MCPs)
Model predictions (10 m MCPs)
Model predictions (5 m MCPs)
Amplitude / V
number of deteced ions
Experimental data (5 m MCPs)
10
-0.05
-0.10
Rise time=0.6 ns
Rise time=0.4 ns
Fall time=1.7 ns
Fall time=0.5 ns
FWHM=1.1 ns
FW HM=0.6 ns
1
-0.15
typical MCP signal (TOF)
with new anode
0.1
1
10
100
1000
10000
-2
turn number
0
2
4
time / ns
Figure 18: Panel (Left): Development of the average ion number found per turn. Green
squares present the experimental data with 5 µm MCPs, black squares show the data with
10 µm MCPs. Red triangles and squares show the corresponding calculations. All the
data are scaled with a charge number Z2 /A and normalized to 14 ions at turn number 10.
Panel (Right): MCP signal shape from a present (black curve) and new anode design (red
curve).
rate from 10 MHz to 100 MHz [2].
The analysis of both experimental data confirms that the calculated function with an
exponential decrease of detection efficiency describes the data within a reasonable agreement. Achieved results as it was expected from off-line measurements and calculations,
less amount of energy loss in thinner carbon foil and about 4 times higher rate resistant 5
µm pore size MCPs are significantly improved an ion survival in the ring.
Optimization of the MCP signal quality. A new design of an anode was made to
optimize the MCP signal quality. First tests show that by decreasing the capacitance
between the anode and the MCPs the peak width can be reduced by a factor of up to two
and the rise time improved by about of 20% (Fig. 18 (Right Panel)).
The rising slope influences the precision of the timing determination and the resolution,
while with smaller value of the falling slope better separation between the weak and strong
close signals can be performed during the data analysis.
[1] N. Kuzminchuk et al., GSI Annual Report 2009 (2010) 35.
[2] B. Fabian, PhD thesis, Universität Gießen, 2008.
Further advances in the development of a MR-TOF-MS for the LEB
A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is a compact, highperformance, multi-purpose, non scanning mass spectrometer [1]. A MR-TOF-MS has
been built and characterized [2]. It features high mass resolution (≥ 105 ), high mass
accuracy (≈ 10−7 ), fast operation (≈ ms), high transmission efficiency (up to 70 %) and
65
single ion sensitivity. It is intended for use at low energy radioactive ion beam (RIB)
facilities as an isobar separator, for direct mass measurements of very short-lived nuclei
and as a diagnostic device. In particular, the MR-TOF-MS is part of the Low-Energy
Branch of the Super-FRS at FAIR [3].
Current status and further developments. Based on the settings found previously
[4], further optimization gained improved insight in the instrument. The mass resolving
power has been improved by a factor of two to 600,000. This resolving power is independent
on the number of ions over a large range of ions per cycle (Fig. 19).
Developments for further advances in the instrument’s performance are underway. Currently, the achievable mass resolving power is limited by the stability of the voltages
supplying the analyzer. The electronic circuits stabilizing these voltages have been reengineered, improving the stability from currently 2.5 ppm to 1 ppm. In the current
setup, only the potential on four of the analyzer electrodes was stabilized. For further improvements, all eight electrodes will be provided with stabilizing electronics. Additionally,
high precision power supplies have been acquired.
The current temperature dependence of the TOF is 20 ppm/K. The integration of the
re-engineered electronics and a temperature stabilization of the system will gain an improvement of an order of magnitude. The extremeley low dark count rate of the detector
in the interval of a mass line (≈ 1 per year) allow mass measurements of extremely rare
nuclides.
Further improvements that will be implemented are the removal of mechanical deficiencies,
an improved ion-optical layout and the increase of the kinetic energy of the ions from 750
eV to 1.3 keV.
It is assumed that by implementing these improvements, the mass resolving power of the
MR-TOF-MS will be increased by a factor 2, bringing the resolution of many isomeric
states within reach.
Rm(FWHM) = 600,000
-5
t = 41 ns
-10
-15
Measured Signal
Mass Resolving Power (FWHM)
Detector Signal /mV
0
5
7x10
5
6x10
5
5x10
5
4x10
5
3x10
5
2x10
5
1x10
0
0
10
Gaussian Fit
-100
0
20
30
40
50
Detected Ions per Cycle
100
200
300
400
500
(t - t
) / ns
Cs
Figure 19: Mass spectrum of 133 Cs with a mass resolving power of 600,000 FWHM. Note
the Gaussian peak shape. Inset: Dependence of the resolving power on number of ions
per cycle.
66
For the use of the MR-TOF-MS as isobar separator, the efficient recapture of the ions after
mass separation and subsequent transport to the connected experiments is paramount.
An energy buncher [1], utilizing pulsed and static retarding fields, has been designed.
Simulations show that the buncher will enable efficient injection into a recapture RFQ by
reducing the energy distribution by a factor ≈ 20.
Outlook A second MR-TOF-MS intended and customized for isobar separation at TITAN
of TRIUMF (Canada) is in design state, featuring a novel type of RFQ-type switch yard.
It will be used as a prototype for MR-TOF-MS at other facilities.
First mass measurements of exotic nuclei with the present MR-TOF-MS will be performed
at the FRS Ion Catcher in 2011.
[1]
[2]
[3]
[4]
W. R. Plaß et al., Nucl. Instrum. Methods B, 266 (2008) 4560.
T. Dickel, Doktorarbeit, Justus-Liebig-Universität, 2010.
D. Rodriguez et al., EPJST, 183 (2010).
T. Dickel et al., GSI Scientific Report 2009, p. 28.
A mobile high-resolution MR-TOF-MS for in-situ analytics
The goal of the LOEWE-Schwerpunkt AmbiProbe is the development of new mass spectrometric tools and methods for in-situ analytics applied to the fields of health, environmental and climate research as well as security. In-situ analytics require direct and reliable
sampling of ions from the environment and mobile mass spectrometers with minimum
infrastructural requirements. Developments performed within AmbiProbe will allow for
innovative and hitherto inaccessible applications.
One of these developments is a mobile high-resolution multiple-reflection time-of-flight
mass spectrometer (MR-TOF-MS). It has been designed and built and is currently being
commissioned. The concept of the device is based on the previous development of an
MR-TOF-MS for applications in nuclear physics [1,2]. The MR-TOF-MS consists of an
atmospheric pressure interface (API) for different atmospheric ion sources, an RF cooler
quadrupole, an RF ion trap, an time-of-flight analyzer and an MCP detector. It is placed
in a differentially pumped recipient and mounted with all components required for its
operation, such as vacuum pumps, power supplies and data acquisition system, in a mobile
frame with a total volume of only 0.8 m3 (Fig. 20).
For the first time, this MR-TOF-MS will allow for high-resolution (m/∆m > 105 ) and
highly accurate (δm/m < 10−6 ) mass analysis in a mobile device. Envisaged applications include the direct analysis of tissue during electro-surgery in the operating room
to distinguish between cancerous and healthy tissue [3], the in-situ determination of the
composition and structure and of biomolecules [4] as well as the investigation of soil and
water samples samples for environmental purposes.
[1] W.R. Plaß et al., Nucl. Instrum. Methods B, 266 (2008) 4560.
[2] T. Dickel, doctoral thesis, Justus-Liebig-Universität Gießen, 2010.
67
Figure 20: Schematic figure and photo of the mobile multiple-reflection time-of-flight mass
spectrometer developed within the AmbiProbe project.
[3] K.-C. Schäfer et al., Angew. Chem. Int. Ed. 48 (2009) 8240.
[4] B. Spengler, J. Am. Soc. Mass Spectrom. 15 (2004) 703.
FRS Ion Catcher: Setup, status and perspectives
At the FRS Ion Catcher at GSI, exotic nuclei, which have been produced by projectile fragmentation or fission and separated and range-bunched in the FRS, will be slowed-down,
thermalized in a cryogenic stopping cell, extracted and made available to precision experiments with ions almost at rest. A novel multiple-reflection time-of-flight mass spectrometer
(MR-TOF-MS) [1-2] will be used to perform mass measurements of very short-lived and
rare nuclei (half-lives down to ms, ∼10 detected nuclei) with accuracies on the level of
10−7 . It will also provide isobarically clean beams for mass-resolved decay spectroscopy
experiments. In addition, the FRS Ion Catcher will serve as test bench for the cryogenic
stopping cell [3] of the Low-Energy Branch (LEB) of the Super-FRS at FAIR.
The beam line of the FRS Ion Catcher (Fig. 21) is designed according to a novel concept [4]:
It is based on a versatile system of RF quadrupoles (RFQs), which despite its compactness
(length ∼2 m) allows for differential pumping in the vicinity of the stopping cell and for
ion beam cooling, transport, bunching, beam monitoring and mass separation. It is thus
ideally suited to the space-restricted area at the final focus of the FRS. Vacuum separation
between stopping cell and beam line is realized using a gate valve and a retractable RFQ
segment. An electrically switchable RFQ switchyard enables introduction of reference
ions from alkali and laser ablation ion sources as well as distribution of ions to different
experimental stations. A triple-RFQ system that implements a subset of these capabilities
68
Figure 21: Schematic figure of the FRS Ion Catcher setup. Exotic nuclei produced, separated and range-bunched in the FRS are injected into the cryogenic stopping cell. They
are thermalized and extracted using DC and RF electric fields and separated from the
buffer gas in an extraction RFQ. Various detectors can be moved into the RFQ beam
line. Introduction of reference ions and ion beam distribution is achieved using an RFQ
beam switchyard. A multiple-refelcetion time-of-flight mass spectrometers serves for highresolution mass mass measurements and as isobar separator.
has recently been developed for the SHIPTRAP facility and has been shown to provide ion
beam cooling, bunching and mass separation with a suppression of neighboring isotopes
by at least 4 orders of magnitude, while achieving a transmission efficiency of almost unity
[5].
The beam line of the FRS Ion Catcher is currently under construction and will be installed
at GSI together with the stopping cell and the MR-TOF-MS during the first half of 2011.
A first on-line experiment is planned to be performed shortly afterwards. Besides on-line
commissioning of the cryogenic stopping cell of the LEB, the experimental program will
address mass measurements and decay spectroscopy of both, very neutron-rich nuclides,
e.g. at the N=82 shell closure, and very proton rich nuclides, such as heavy N=Z nuclei.
[1]
[2]
[3]
[4]
[5]
W.R. Plaß et al., Nucl. Instrum. Methods B 266 (2008) 4560.
T. Dickel, PhD Thesis, Gießen University (2010).
S. Purushothaman et al., GSI Sci. Rep. 2009 (2010) 27.
W.R. Plaß et al., Eur. Phys. J. Special Topics 150 (2007) 367.
E. Haettner et al., GSI Sci. Rep. 2010, to be published.
69
1. H. Geissel
NUSTAR Experiments at GSI
Institute of Nuclear Physics PAN, Cracow (Poland), January 2010
2. H. Geissel
Experiments with Stored Exotic Nuclei
Chalmers Subatomic Physics, Gøteborg (Sweden), May 2010
3. W. R. Plaß
Physik mit gespeicherten exotischen Kernen
Physikalisches Kolloquium, Justus-Liebig-Universität Gießen, 14. June 2010
Publications
1. Lifetime effects for high-resolution gamma-ray spectroscopy at relativistic
energies and their implications for the RISING spectrometer
P. Doornenbal, P. Reiter, H. Grawe, T. Saito, A. Al-Khatib, A. Banu, T. Beck, F.
Becker, P. Bednarczyk, G. Benzoni, A. Bracco, A. Burger, L. Caceres, F. Camera,
S. Chmel, F. C. L. Crespi, H. Geissel, J. Gerl, M. Gorska, J. Grebosz, H. Hubel,
M. Kavatsyuk, O. Kavatsyuk, M. Kmiecik, I. Kojouharov, N. Kurz, R. Lozeva, A.
Maj, S. Mandal, W. Meczynski, B. Million, Zs. Podolyak, A. Richard, N. Saito, H.
Schaffner, M. Seidlitz, T. Striepling, J. Walker, N. Warr, H. Weick, O. Wieland, M.
Winkler, H. J. Wollersheim
Nucl. Instrum. Methods Phys. Res., Sect. A 613 (2010) 218 .
2. Direct mass measurements above uranium bridge the gap to the island
of stability
M. Block, D. Ackermann, K. Blaum, C. Droese, M. Dworschak, S. Eliseev, T. Fleckenstein, E. Haettner, F. Herfurth, F. P. Hessberger, S. Hofmann, J. Ketelaer, J. Ketter, H.-J. Kluge, G. Marx, M. Mazzocco, Yu. N. Novikov, W. R. Plaß, A. Popeko,
S. Rahaman, D. Rodriguez, C. Scheidenberger, L. Schweikhard, P. G. Thirolf, G. K.
Vorobyev, C. Weber
Nature 463 (2010) 785 .
3. Studies of two-body beta-decays at the FRS-ESR facility
J. Kurcewicz, F. Bosch, H. Geissel, Yu. A. Litvinov, N. Winckler, K. Beckert, P.
Beller, D. Boutin, C. Brandau, L. Chen, C. Dimopoulou, H. G. Essel, B. Fabian, T.
Faestermann, A. Fragner, B. Franzke, E. Haettner, M. Hausmann, S. Hess, P. Kienle,
R. Knöbel, C. Kozhuharov, S. A. Litvinov, L. Maier, M. Mazzocco, F. Montes, A.
Musumarra, C. Nociforo, F. Nolden, Z. Patyk, W. R. Plaß, A. Prochazka, R. Reda,
R. Reuschl, C. Scheidenberger, M. Steck, T. Stöhlker, B. Sun, K. Takahashi, S.
Torilov, M. Trassinelli, H. Weick, M. Winkler
Acta Phys. Pol. B 41 (2010) 525 .
4. Direct mass measurements of exotic nuclei in storage rings
Y. A. Litvinov, H. Geissel, R. Knöbel, B. Sun, H. Xu
70
Acta Phys. Pol. B 41 (2010) 511 .
5. One-neutron knockout of n-rich Ne isotopes at relativistic energies
D. Cortina-Gil, C. Rodriguez-Tajes, H. Alvarez-Pol, E. Benjamim, J. Benlliure, M. J.
G. Borge, M. Caamano, E. Casarejos, A. Chatillon, K. Eppinger, T. Faestermann,
M. Gascon, H. Geissel, R. Gernhäuser, B. Jonson, R. Kanungo, R. Krücken, T.
Kurtukian, P. Maierbeck, T. Nilsson, C. Nocciforo, C. Pascual-Izarra, A. Perea, D.
Perez-Loureiro, A. Prochazka, H. Simon, K. Sümmerer, O. Tengblad, H. Weick, M.
Zhukov
Nucl. Phys. A 834 (2010) 485C .
6. Precise measurement of nuclear isomers in the storage ring at GSI
B. Sun, F. Bosch, D. Boutin, C. Brandau, L. Chen, C. Dimopoulou, B. Fabian, H.
Geissel, R. Knöbel, C. Kozhuharov, J. Kurcewicz, S. A. Litvinov, Yu. A. Litvinov,
J. Meng, G. Münzenberg, C. Nociforo, F. Nolden, W. R. Plaß, C. Scheidenberger,
M. Steck, P. M. Walker, H. Weick, N. Winckler, M. Winkler
Nucl. Phys. A 834 (2010) 476C .
7. Measurements of nuclear radii for neutron-rich Ne isotopes Ne28-32
M. Takechi, T. Ohtsubo, T. Kuboki, M. Fukuda, D. Nishimura, T. Suzuki, T. Yamaguchi, A. Ozawa, T. Moriguchi, T. Sumikama, H. Geissel, N. Aoi, N. Fukuda, I.
Hachiuma, N. Inabe, Y. Ishibashi, Y. Itoh, D. Kameda, K. Kusaka, M. Lantz, M.
Mihara, Y. Miyashita, S. Momota, K. Namihira, H. Ohishi, Y. Ohkuma, T. Ohnishi,
M. Ohtake, K. Ogawa, Y. Shimbara, T. Suda, S. Suzuki, H. Takeda, K. Tanaka, R.
Watanabe, M. Winkler, Y. Yanagisawa, Y. Yasuda, K. Yoshinaga, A. Yoshida, K.
Yoshida, T. Kubo
Nucl. Phys. A 834 (2010) 412C .
8. Structure of Mg-33 sheds new light on the N=20 island of inversion
R. Kanungo, C. Nociforo, A. Prochazka, Y. Utsuno, T. Aumann, D. Boutin, D.
Cortina-Gil, B. Davids, M. Diakaki, F. Farinon, H. Geissel, R. Gernhäuser, J. Gerl,
R. Janik, B. Jonson, B. Kindler, R. Knöbel, R. Krücken, M. Lantz, H. Lenske, Y.
Litvinov, K. Mahata, P. Maierbeck, A. Musumarra, T. Nilsson, T. Otsuka, C. Perro,
C. Scheidenberger, B. Sitar, P. Strmen, B. Sun, I. Szarka, I. Tanihata, H. Weick, M.
Winkler
Phys. Lett. B 685 (2010) 253 .
9. One-neutron knockout from Ne24-28 isotopes
C. Rodriguez-Tajes, D. Cortina-Gil, H. Alvarez-Pol, T. Aumann, E. Benjamim, J.
Benlliure, M. J. G. Borge, M. Caamano, E. Casarejos, A. Chatillon, K. Eppinger,
T. Faestermann, M. Gascon, H. Geissel, R. Gernhäuser, B. Jonson, R. Kanungo,
R. Krücken, T. Kurtukian, K. Larsson, P. Maierbeck, T. Nilsson, C. Nociforo, C.
Pascual-Izarra, A. Perea, D. Perez-Loureiro, A. Prochazka, H. Simon, K. Sümmerer,
O. Tengblad, H. Weick, M. Winkler, M. Zhukov
Phys. Lett. B 687 (2010) 26 .
10. Direct measurement of the 4.6 MeV isomer in stored bare Sb-133 ions
B. Sun, R. Knöbel, H. Geissel, Yu. A. Litvinov, P. M. Walker, K. Blaum, F. Bosch,
D. Boutin, C. Brandau, L. Chen, I. J. Cullen, A. Dolinskii, B. Fabian, M. Hausmann,
71
C. Kozhuharov, J. Kurcewicz, S. A. Litvinov, Z. Liu, M. Mazzocco, J. Meng, F.
Montes, G. Münzenberg, A. Musumarra, S. Nakajima, C. Nociforo, F. Nolden, T.
Ohtsubo, A. Ozawa, Z. Patyk, W. R. Plaß, C. Scheidenberger, M. Steck, T. Suzuki,
H. Weick, N. Winckler, M. Winkler, T. Yamaguchi
Phys. Lett. B 688 (2010) 294 .
11. MATS and LaSpec: High-precision experiments using ion traps and lasers
at FAIR
D. Rodriguez, K. Blaum, W. Nörtershäuser, M. Ahammed, A. Algora, G. Audi, J.
Aysto, D. Beck, M. Bender, J. Billowes, M. Block, C. Böhm, G. Bollen, M. Brodeur,
T. Brunner, B. A. Bushaw, R. B. Cakirli, P. Campbell, D. Cano-Ott, G. Cortes, J.
R. Crespo Lopez-Urrutia, P. Das, A. Dax, A. De, P. Delheij, T. Dickel, J. Dilling, K.
Eberhardt, S. Eliseev, S. Ettenauer, K. T. Flanagan, R. Ferrer, J.-E. Garcia-Ramos,
E. Gartzke, H. Geissel, S. George, C. Geppert, M. B. Gomez-Hornillos, Y. Gusev,
D. Habs, P.-H. Heenen, S. Heinz, F. Herfurth, A. Herlert, M. Hobein, G. Huber, M.
Huyse, C. Jesch, A. Jokinen, O. Kester, J. Ketelaer, V. Kolhinen, I. Koudriavtsev,
M. Kowalska, J. Kramer, S. Kreim, A. Krieger, T. Kühl, A. M. Lallena, A. Lapierre,
F. Le Blanc, Y. A. Litvinov, D. Lunney, T. Martinez, G. Marx, M. Matos, E. MinayaRamirez, I. Moore, S. Nagy, S. Naimi, D. Neidherr, D. Nesterenko, G. Neyens, Y.
N. Novikov, M. Petrick, W. R. Plaß, A. Popov, W. Quint, A. Ray, P.-G. Reinhard,
J. Repp, C. Roux, B. Rubio, R. Sanchez, B. Schabinger, C. Scheidenberger, D.
Schneider, R. Schuch, S. Schwarz, L. Schweikhard, M. Seliverstov, A. Solders, M.
Suhonen, J. Szerypo, J. L. Tain, P. G. Thirolf, J. Ullrich, P. Van Duppen, A. Vasiliev,
G. Vorobjev, C. Weber, K. Wendt, M. Winkler, D. Yordanov, F. Ziegler
Eur. Phys. J. - Special Topics 183 (2010) 1 .
12. Penning trap mass measurements on nobelium isotopes
M. Dworschak, M. Block, D. Ackermann, G. Audi, K. Blaum, C. Droese, S. Eliseev,
T. Fleckenstein, E. Haettner, F. Herfurth, F. P. Hessberger, S. Hofmann, J. Ketelaer, J. Ketter, H.-J. Kluge, G. Marx, M. Mazzocco, Yu. N. Novikov, W. R. Plaß,
A. Popeko, S. Rahaman, D. Rodriguez, C. Scheidenberger, L. Schweikhard, P. G.
Thirolf, G. K. Vorobyev, M. Wang, C. Weber
Phys. Rev. C 81 (2010) 064312 .
13. Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight
Fission of a U-238 Beam at 345 MeV/nucleon
T. Ohnishi, T. Kubo, K. Kusaka, A. Yoshida, K. Yoshida, M. Ohtake, N. Fukuda, H.
Takeda, D. Kameda, K. Tanaka, N. Inabe, Y. Yanagisawa, Y. Gono, H. Watanabe,
H. Otsu, H. Baba, T. Ichihara, Y. Yamaguchi, M. Takechi, S. Nishimura, H. Ueno, A.
Yoshimi, H. Sakurai, T. Motobayashi, T. Nakao, Y. Mizoi, M. Matsushita, K. Ieki,
N. Kobayashi, K. Tanaka, Y. Kawada, N. Tanaka, S. Deguchi, Y. Satou, Y. Kondo,
T. Nakamura, K. Yoshinaga, C. Ishii, H. Yoshii, Y. Miyashita, N. Uematsu, Y.
Shiraki, T. Sumikama, J. Chiba, E. Ideguchi, A. Saito, T. Yamaguchi, I. Hachiuma,
T. Suzuki, T. Moriguchi, A. Ozawa, T. Ohtsubo, M. A. Famiano, H. Geissel, A. S.
Nettleton, O. B. Tarasov, D. P. Bazin, B. M. Sherrill, S. L. Manikonda, J. A. Nolen
J. Phys. Soc. Jpn. 79 (2010) 073201 .
14. Measurements of interaction cross sections towards neutron-rich Ne isotopes at RIBF
72
M. Takechi, T. Ohtsubo, T. Kuboki, M. Fukuda, D. Nishimura, T. Suzuki, T. Yamaguchi, A. Ozawa, T. Moriguchi, T. Sumikama, H. Geissel, N. Aoi, N. Fukuda, I.
Hachiuma, N. Inabe, Y. Ishibashi, Y. Itoh, D. Kameda, T. Kubo, K. Kusaka, M.
Lantz, M. Mihara, Y. Miyashita, S. Momota, K. Namihira, H. Ohishi, Y. Ohkuma,
T. Ohnishi, M. Ohtake, K. Ogawa, Y. Shimbara, T. Suda, S. Suzuki, H. Takeda, K.
Tanaka, R. Watanabe, M. Winkler, Y. Yanagisawa, Y. Yasuda, K. Yoshinaga, A.
Yoshida, K. Yoshida
Mod. Phys. Lett. A 25 (2010) 1878 .
15. Discovery and investigation of heavy neutron-rich isotopes with timeresolved Schottky spectrometry in the element range from thallium to
actinium
L. Chen, W. R. Plaß, H. Geissel, R. Knöbel, C. Kozhuharov, Yu. A. Litvinov, Z.
Patyk, C. Scheidenberger, K. Siegien-Iwaniuk, B. Sun, H. Weick, K. Beckert, P.
Beller, F. Bosch, D. Boutin, L. Caceres, J. J. Carroll, D. M. Cullen, I. J. Cullen, B.
Franzke, J. Gerl, M. Gorska, G. A. Jones, A. Kishada, J. Kurcewicz, S. A. Litvinov,
Z. Liu, S. Mandal, F. Montes, G. Münzenberg, F. Nolden, T. Ohtsubo, Z. Podolyak,
R. Propri, S. Rigby, N. Saito, T. Saito, M. Shindo, M. Steck, P. Ugorowski, P. M.
Walker, S. Williams, M. Winkler, H.-J. Wollersheim, T. Yamaguchi
Phys. Lett. B 691 (2010) 234 .
16. One-neutron knockout from light neutron-rich nuclei at relativistic energies (vol 82, art no 024305, 2010)
C. Rodriguez-Tajes, H. Alvarez-Pol, T. Aumann, K. Benjamim, J. Benlliure, M. J.
G. Borge, M. Caamano, E. Casarejos, A. Chatillon, D. Cortina-Gil, K. Eppinger,
T. Faestermann, M. Gascon, H. Geissel, R. Gernhäuser, B. Jonson, R. Kanungo,
R. Krücken, T. Kurtukian, K. Larsson, P. Maierbeck, T. Nilsson, C. Nociforo, C.
Pascual-Izarra, A. Perea, D. Perez-Loureiro, A. Prochazka, S. Schwertel, H. Simon,
K. Sümmerer, O. Tengblad, H. Weick, M. Winkler, M. Zhukov
Phys. Rev. C 82 (2010) 029910 .
17. Nuclear astrophysics experiments with stored, highly-charged ions at
FRS-ESR at GSI
C. Scheidenberger
AIP Conf. Proceed. 1269 (2010) 69 .
18. Isomer spectroscopy of Cd-127
F. Naqvi, M. Gorska, L. Caceres, A. Jungclaus, M. Pfützner, H. Grawe, F. Nowacki,
K. Sieja, S. Pietri, E. Werner-Malento, P. H. Regan, D. Rudolf, Z. Podolyak, J.
Jolie, K. Andgren, T. Beck, P. Bednarczyk, J. Benlliure, G. Benzoni, A. M. Bruce,
E. Casarejos, B. Cederwall, F. C. L. Crespi, P. Detistov, Zs. Dombradi, P. Doornenbal, H. Geissel, J. Gerl, J. Grebosz, B. Hadinia, M. Hellstrom, R. Hoischen, G. Ilie,
A. Khaplanov, I. Kojouharov, M. Kmiecik, N. Kurz, S. Lalkovski, A. Maj, S. Mandal, V. Modamio, F. Montes, S. Myalski, W. Prokopowicz, P. Reiter, H. Schaffner,
G. Simpson, D. Sohler, S. J. Steer, S. Tashenov, J. Walker, O. Wieland, H. J. Wollersheim
Phys. Rev. C 82 (2010) 034323 .
19. Shape coexistence and isomeric states in neutron-rich Tc-112 and Tc-113
73
A. M. Bruce, S. Lalkovski, A. M. Denis Bacelar, M. Gorska, S. Pietri, Zs. Podolyak,
Y. Shi, P. M. Walker, F. R. Xu, P. Bednarczyk, L. Caceres, E. Casarejos, I. J. Cullen,
P. Doornenbal, G. F. Farrelly, A. B. Garnsworthy, H. Geissel, W. Gelletly, J. Gerl,
J. Grebosz, C. Hinke, G. Ilie, G. Jaworski, I. Kojouharov, N. Kurz, S. Myalski, M.
Palacz, W. Prokopowicz, P. H. Regan, H. Schaffner, S. Steer, S. Tashenov, H. J.
Wollersheim
Phys. Rev. C 82 (2010) 044312 .
20. The unbound isotopes He-9, He-10
H. T. Johansson, Yu. Aksyutina, T. Aumann, K. Boretzky, M. J. G. Borge, A.
Chatillon, L. V. Chulkov, D. Cortina-Gil, U. Datta Pramanik, H. Emling, C. Forssen,
H. O. U. Fynbo, H. Geissel, G. Ickert, B. Jonson, R. Kulessa, C. Langer, M. Lantz,
T. LeBleis, K. Mahata, M. Meister, G. Münzenberg, T. Nilsson, G. Nyman, R. Palit,
S. Paschalis,W. Prokopowicz, R. Reifarth, A. Richter, K. Riisager, G. Schrieder, H.
Simon, K. Sümmerer, O. Tengblad, H. Weick, M. V. Zhukov
Nucl. Phys. A 842 (2010) 15 .
21. Reaction cross section studies at NIRS and RIBF
M. Fukuda, M. Takechi, D. Nishimura, M. Mihara, R. Matsumiya, K. Matsuta,
T. Minamisono, T. Ohtsubo, Y. Ohkuma, Y. Shimbara, S. Suzuki, R. Watanabe,
T. Izumikawa, S. Momota, T. Suzuki, T. Yamaguchi, T. Kuboki, I. Hachiuma, K.
Namihira, S. Nakajima, K. Kobayashi, T. Sumikama, Y. Miyashita, K. Yoshinaga,
K. Tanaka, N. Aoi, N. Fukuda, N. Inabe, D. Kameda, T. Kubo, K. Kusaka, M.
Lantz, T. Ohnishi, M. Ohtake, T. Suda, H. Takeda, Y. Yanagisawa, A. Yoshida, K.
Yoshida, A. Ozawa, T. Moriguchi, H. Ohishi, Y. Itoh, Y. Ishibashi, K. Ogawa, Y.
Yasuda, H. Geissel, M. Winkler, S. Sato, M. Kanazawa, A. Kitagawa
AIP Conf. Proceed. 1238 (2010) 270 .
22. Discovery of Highly Excited Long-Lived Isomers in Neutron-Rich
Hafnium and Tantalum Isotopes through Direct Mass Measurements
M. W. Reed, I. J. Cullen, P. M. Walker, Yu. A. Litvinov, K. Blaum, F. Bosch,
C. Brandau, J. J. Carroll, D. M. Cullen, A. Y. Deo, B. Detwiller, C. Dimopoulou,
G. D. Dracoulis, F. Farinon, H. Geissel, E. Haettner, M. Heil, R. S. Kempley, R.
Knöbel, C. Kozhuharov, J. Kurcewicz, N. Kuzminchuk, S. Litvinov, Z. Liu, R. Mao,
C. Nociforo, F. Nolden, W. R. Plaß, A. Prochazka, C. Scheidenberger, M. Steck, T.
Stöhlker, B. Sun, T. P. D. Swan, G. Trees, H. Weick, N. Winckler, M. Winkler, P.
J. Woods, T. Yamaguchi
Phys. Rev. Lett. 105 (2010) 172501 .
23. Three-body correlations in the decay of He-10 and Li-13
H. T. Johansson, Y. Aksyutina, T. Aumann, K. Boretzky, M. J. G. Borge, A. Chatillon, L. V. Chulkov, D. Cortina-Gil, U. Datta Pramanik, H. Emling, C. Forssen, H.
O. U. Fynbo, H. Geissel, G. Ickert, B. Jonson, R. Kulessa, C. Langer, M. Lantz, T.
LeBleis, K. Mahata, M. Meister, G. Münzenberg, T. Nilsson, G. Nyman, R. Palit,
S. Paschalis, W. Prokopowicz, R. Reifarth, A. Richter, K. Riisager, G. Schrieder, N.
B. Shulgina, H. Simon, K. Sümmerer, O. Tengblad, H. Weick, M. V. Zhukov
Nucl. Phys. A 847 (2010) 66 .
74
1. SHIPTRAP Collaboration Meeting, GSI Darmstadt, 27. January 2010
W.R. Plaß
Mass Measurement of rp-Nuclei at SHIPTRAP and Developments for Mass Spectrometry and Decay Spectroscopy
2. ILIMA Collaboration Meeting, GSI Darmstadt, 2. March 2010
W.R. Plaß
Time-of-Flight Detectors for Isochronous Mass Spectrometry
3. Annual NUSTAR Meeting, GSI Darmstadt, 2. - 5. March 2010
W.R. Plaß
A Novel Mass Spectrometer for Precision Experiments with Exotic Nuclei, (invited
talk)
4. DPG Frühjahrstagung, AMOP, Hannover, 8.-12. March 2010
W. R. Plaß
Progress in Mass Spectrometry of Exotic Nuclei at the FRS-ESR Facility at
GSI, (Hauptvortrag)
T. Dickel
MR-TOF-MS: A Time-of-Flight-Based System with sub-ppm Mass Measurement Accuracy and Large Isobar Separation Ion Capacity (> 106 ions/s)
F. Lautenschläer
Design and Construction of an Energy Buncher for a Multiple-Reflection Timeof-Flight Isobar Separator
D. Schäfer
Simulations of a stopping cell for the LEB of the Super-FRS at FAIR
T. Schäfer
An RFQ beam preparation system for SHIPTRAP
5. OMEG-10 (Origin of Matter and Evolution of Galaxies), Osaka, Japan,
8. - 10. March 2010
C. Scheidenberger
Storage-ring experiments for nuclear astrophysics at GSI
6. DPG Frühjahrstagung, Hadronen und Kerne, Bonn, 15. - 19. March
2010
S. Ayet
A Fast Microchannel-Plate Detector and High-Performance Electronics for Signal Conditioning
E. Haettner
Mass measurements of the proton-rich nuclides 85,86,87 M o and 87 T c and their
impact on the rp-process
C. Jesch
An MR-TOF-MS Isobar Separator and its Applications for TITAN at TRIUMF
and the LEB at FAIR
R. Knöbel
Recent Results of Mass Measurements at the Experimental Storage Ring at GSI
75
N. Kuzminchuk
Developments for a New Isochronous Mass Spectrometry Experiment with Uranium Fission Fragments at the FRS-ESR Facility at GSI
7. EURORIB, Lamoura, France, June 2010
H. Geissel
Experiments with Exotic Nuclei applying a new Generation of In-flight Separators
and Spectrometers
8. IUPAP WG-9 Two-Day Symposium at TRIUMF on Nuclear Physics and
Nuclear Physics Facilities, Vancouver (Canada), 2. - 3. July 2010
C. Scheidenberger
ENSAR - European Nuclear Structure and Application Research
9. WE-Heraeus Summer School on Nuclear Astrophysics in the Cosmos,
Darmstadt (Germany), 12.-17. July 2010
C. Scheidenberger
Exotic Nuclei
10. 11th Symposium on Nuclei in the Cosmos (NIC XI), Heidelberg, 19. 23. July 2010
E. Haettner
Mass measurements of proton-rich nuclides in the region of A=85 and their impact
on the rp-process
11. NUSTAR Seminar, GSI Darmstadt, 14. July 2010
T. Dickel
MR-TOF-MS: A versatile and powerful mass spectrometer and isobar separator for
low-energy rare ion beam facilities
12. AmbiProbe-Klausurtagung, Kleinwalsertal, 8. July, 2010
J. Lang
Development Of A Mobile Time-Of-Flight Mass Spectrometer For Ambient And
In-Situ Analysis
W.R. Plaß
Mobile High-Resolution Multiple-Reflection Time-of-Flight Mass Spectrometry
13. NUSTAR-Fall Meeting, Lund (Sweden) October 2010
H. Geissel
Super-FRS Status and Planned Experiments
14. FRS-User-Meeting, GSI Darmstadt, 08.-09. November 2010
R. Knöbel
Report on E084 ESR Experiment
15. ESR-Coordination-Meeting, GSI Darmstadt, 10. November 2010
R. Knöbel
ESR: Time - of - Flight - detector
76
16. Helmholtz-Akademie für Führungskräfte, Liebenberg (Germany) 11.-12.
November 2010
C. Scheidenberger
Freiheit der Forschung oder Führen mit Zielen?
17. Beschleuniger-Palaver, GSI Darmstadt, 18. November 2010
T. Dickel
Isobar Separation, Mass Measurements and Versatile Diagnosis for Rare Isotope Ion
Beams with a Multiple Reflection Time-of-Flight Mass Spectrometer
18. JYFL Future Physics Workshop, Jyväskylä (Finland), 15. - 16. November 2010
W.R. Plaß
High-Resolution Time-of-Flight Mass Spectrometry at Low-Energy RIB Facilities
C. Scheidenberger
NuSTAR and European landscape
77
78
Group of Dr. I. Dillmann
Sekretariat:
Christa Momberger
Academic:
Dr. Iris Dillmann
PhD Students:
Alexey A. Evdokimov (since 11/2010)
79
LISA- Lifetime Spectroscopy for Astrophysics
The Helmholtz Young Investigators group ”LISA- Lifetime Spectroscopy” for Astrophysics
exists since January 2010. The main topic of this group are experiments for r-process
nucleosynthesis at the Fragment Separator FRS and the Experimental Storage Ring ESR,
but also the maintenance and extension of the ”Karlsruhe Astrophysical Database of
Nucleosynthesis in Stars” project (www.kadonis.org), a database for stellar cross sections of
the s- and p-process. The research group is funded for 5 years by the Helmholtz association
and the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. At the JustusLiebig Universität Giessen the group is reading the lecture about ”Nukleare Astrophysik
II” (MP30-N) during the summer term, and is supporting the lecture ”Experimentelle
Nukleare Astrophysik” (MP41) of Prof. Dr. C. Scheidenberger during the winter term.
No other astrophysical process than the rapid neutron capture process (r process) is used
more often to motivate the necessity of the new-generation radioactive beam facilities with
higher beam intensities. In the dawn of these facilities (RIBF at RIKEN, FRIB at Michigan
State University, and FAIR in Darmstadt) experiments carried out at the presently existing
facilities mark a transition between the past and the future. Two of such facilities are FRS
and the ESR at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt. Up to
now one could only ”scratch” the regions where the r process takes place - with exception
of the N =126 region, which remains an experimental ”terra incognita” (Fig. 22). Owing
to the upgrade of the GSI accelerator and to the development of new highly sensitive and
efficient detection techniques in view of the future FAIR facility, planned experiments at
the FRS and ESR aim at filling this gap, approaching the r-process path also at N =126
[1].
Nuclear physics input for r-process calculations
Since the r-process path runs exclusively through very neutron-rich regions far off the valley of β-stability, almost all of its parameters for a calculation of the progenitor abundances
have to be inferred from theoretical predictions. The astrophysical input parameters are
the temperature (T ≈1-2 GK), the neutron density (nn ≈1020 −1030 cm−3 ), and the duration of the neutron exposure (τ ≈1−10 s). The most important input parameters from
nuclear physics during the equilibrium phase are masses (neutron separation energies Sn ,
reaction Q values), and the half-lives t1/2 of the participating nuclei. The masses determine
the reaction path of the r process, and the half-lives of the respective waiting-point nuclei
how much material is transferred from one isotopic chain to the next, thus the amount of
the progenitor abundances.
When the temperature drops or the neutron flux ceases and the reaction flow drops out of
equilibrium, β-delayed neutron emission probabilities (Pn values) are required since they
divert the β-decay chains into neighboring nuclei and wash out the observed abundance
curve. In this freeze-out phase neutron capture cross sections are needed, as well as αdecay half-lives for isotopes above A≥210. For nuclides with Z>80 also fission parameters
become important, like barriers, β-delayed fission probabilities, and (neutron-induced)
80
0
ra
bu
nd
an
ce
s
25
0
20
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98
lar
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92
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68
R
TE
66
64
62
0
−1
−2
10
50
48
164 168 172
162 166 170 174
160
158
156
154
152
150
140 144 148
142
146
138
134136
130132
128
126
124
122
120
116118
112114
110
108
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100102
98
r−path
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40
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7476
32
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6668
28
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26
60
28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58
86 88 90
N=82
N=50
188190
186
184
180182
178
176
N=184
N=126
52
10
10
10
1
60
58
56
54
RA
ITA
N
OG
C
IN
Identified
Known half−life
Known Pn value
r−process waiting point
Figure 22: Status of β-delayed neutron emission and half-life measurements. The waitingpoints for several (classical) r-process conditions show the region of interest for r-process
measurements.
fission cross sections. The end point of the r process is strongly model dependent and
not as well-defined as the s-process termination point at 210 Bi. It depends entirely on
the calculations of fission barriers, and is reached when the Coulomb energy becomes too
large, most probably in the mass region around Z=94, A=270. Then, neutron-induced,
β-delayed, and spontaneous fission take over and recycle the r-process material back into
the A∼130 region (”fission recycling”).
The prominent peak structures of the solar r-abundance curve at A=80, 130, and 195
are a mirror of nuclear structure far off stability and reflect the shell closures at N =50,
82, and 126 (Fig. 22). Here the neutron capture cross sections are extremely small and
thus the material can be accumulated. Whereas the average time between two neutron
captures is ∼1 ms, the r-process flow pauses at these neutron-magic waiting-points for
several hundred ms. During the freeze-out phase β-decays along an isobaric chain lead
then to those stable isotopes which can be observed in the solar r-process abundance curve,
and β-delayed neutron emissions are smoothing out the existing even-odd staggering. The
peaks at A=80 (130, 195) originate mainly from the N =50 (82, 126) progenitor isotopes
around 80 Zn (130 Cd, 195 Tm). Experimental investigations are thus focussed on these key
regions.
81
With these informations r-process network calculations can be carried out and the calculated abundances can be compared to the observed solar r-abundances Nr derived from
the total solar abundances N⊙ by subtracting the well-understood solar s-abundances,
Nr =N⊙ −Ns . This implies that the deduced solar r-abundances depend strongly on the
accuracy of the respective s-abundances. The calculated r-abundance curves are also
strongly mass model-dependent, thus experimental information is indispensable for verification and improving the predictive power of the models.
A
n
Z
n
S2n
A-2
Z+1
Sn
A-1
Z+1
A
Z+1
Figure 23: Mechanism of β-delayed one- and two-neutron emission.
The mechanism of β-delayed neutron emission is shown in Fig. 23. In very neutronrich isotopes the neutron separation energy Sn can be lower than the reaction Qβ value,
and β-decays from the mother nucleus A Z can lead into excited states above the Sn of
the daughter nuclei. The de-excitation occurs via internal γ-transitions or emission of a
neutron to the nucleus A−1 Z +1. The same holds for two- or more neutron emissions, if the
S2n (Sxn ) is lower than the Qβ value. From the time-dependence of the neutron-emission
one can determine the β-decay half-life of the mother nuclide A Z. The probability of
β-delayed neutron emission (Pn ) carries important nuclear structure informations of the
β-strength of the daughter A Z + 1 above the neutron separation energy. However, for the
prediction of β-delayed neutron emitters accurate mass measurements of very neutron-rich
isotopes are needed.
Experimental situation
Measurements of nuclear properties relevant for the r-process are closely related with the
ability of production and often also efficient separation from contaminants of the corresponding very exotic neutron-rich nuclei. Two main reaction mechanisms are frequently
employed for the production of neutron-rich isotopes. Fission is used for the production
of light and medium-mass nuclei, whereas for heavier neutron-rich isotopes the projectile
fragmentation (spallation) is better suited.
82
Up to now experimental information for r-process nuclei has been obtained only in those
regions where the reaction path approaches the valley of stability (Fig. 22). This occurs
at the shell closures N =50, 82, and 126. The pioneering experiments on isotopes in the
reaction path were the determination of the half-lives of the N =50 isotopes 79 Cu, 80 Zn
[2] and the N =82 isotopes 129 Ag, 130 Cd [3]. Full β- and γ-spectroscopy measurements are
much more elaborate, for example it took 16 years to obtain the first decay scheme of the
waiting-point nuclide 130 Cd [4]. Very recently RIBF at RIKEN Nishina Center achieved
to produce 45 neutron-rich isotopes between 71 Mn and 152 Ba by in-flight fission of a 238 U
beam at 345 MeV/nucleon. Among these isotopes for the first time the neutron-magic
N =82 isotope 128 Pd and the N =85 isotope 133 Cd [5] were identified, though no half-life
or mass measurements could be performed. Although there has been a lot of progress
in the last years, the r-process regions above A>150 and especially around the N =126
waiting point nuclei are still experimental ”terra incognita”, i.e. masses, β-delayed neutron
emission probabilities, and half-lives have not been measured up to now.
Experiments at the GSI radioactive beam facility
The projectile fragment separator FRS [6] at GSI allows efficient purification of monoisotopic secondary beams in flight by means of the analysis of the magnetic rigidity Bρ
combined with the energy loss ∆E in specially shaped energy degraders (Bρ-∆E-Bρ separation technique). The separated secondary isotopes of interest can be implanted and
investigated at the final focal plane of the FRS or alternatively injected and stored in
the cooler-storage ring ESR [7], where their masses or/and β-decay properties can be
addressed [8].
Primary beams provided by the heavy-ion synchrotron SIS-18 are accelerated up to
1 A GeV and focussed on a thick (Be or Pb) target at the entrance of the FRS, where
relativistic fragments of several hundred MeV/u are produced via fragmentation or fission in inverse kinematics. Typically used for the production of neutron-rich isotopes are
e.g. 238 U, 136 Xe, 197 Au, or 208 Pb. A large experimental campaign within the RISING
project at GSI was focussed on the exploration of the region ”south” and ”southwest” of
the doubly-magic 208 Pb, aiming at filling the gap between the previously known isotopes
and the r-process isotopes which are responsible for the N =126 peak, thus nuclei around
195 Tm. However, the heaviest Tm (Z=69) isotope produced up to now is 177 Tm, still 18
mass units away from the reaction path. The situation is a little bit better for heavier isotopes which are responsible for the right wing of the N =126 r-process peak (196 Yb, 197 Lu,
198 Hf, 199 Ta, 200 W, and neighboring isotopes). For W isotopes the gap is presently ”only”
9 neutrons. The neutron-rich isotopes 194,195,196 Re, 199,200 Os, 198,199,202 Ir, and the lightest
N =126 isotope 204 Pt have also been investigated recently by the RISING collaboration
[9,10].
In summer 2011 two experiments [11,12] will be performed at GSI which aim to measure
for the first time half-lives and β-delayed neutron emission probabilities of very neutronrich Pd, Rh (Z=45, 46), as well as Ir, Pt, Au, Hg and Tl (Z=77−81) isotopes (Fig. 24).
83
For these experiments a setup of an implantation detector (SIMBA, Silicon IMplantation
detector and Beta Absorber [13,14]) and a high-efficiency 3 He neutron detector setup
(BELEN, BEta-deLayEd Neutron detector [15], Fig. 25) will be placed at the final focal
plane of the FRS. The determination of half-lives is carried out with the neutron detector
by measuring the time-dependence of β-delayed neutrons after implantation. The βdelayed neutron emission probabilities (Pn values) can be deduced from the correlation of
β-decay and β-delayed neutron detection.
Sn (Z=50)
In (Z=49)
Cd (Z=48)
Ag (Z=47)
Pd (Z=46)
Rh (Z=45)
Ru (Z=44)
Tc (Z=43)
76 78 80 82 84 86 88
Identified
Known half−life
r−process waiting point
bdn measured
bd1/2/3n predicted (>1%)
GSI proposals S323/S410
Po (Z=84)
Bi (Z=83)
Pb (Z=82)
Tl (Z=81)
Hg (Z=80)
Au (Z=79)
Pt (Z=78)
Ir (Z=77)
Os (Z=76)
Re (Z=75)
W (Z=74)
Ta (Z=73)
Hf (Z=72)
Lu (Z=71)
Yb (Z=70)
Tm (Z=69)
114
118
122
126
130
134
138
142
Figure 24: Experimental situation at the N =82 and N =126 shell closures. Shown are
those isotopes to be measured in the GSI campaign 2011 (circles), as well as predictions
from the FRDM(GT+ff) [16] for β-delayed one-, two-, and three-neutron emitters.
The neutron detector BELEN was upgraded in 2010 by inclusion of 10 additional counters.
This upgrade increased the detection efficiency to ≈40% for neutron energies between
1 keV and 1 MeV (Fig. 25). For the FAIR/DESPEC campaign a further upgrade to 44
counters is planned, as well as the use of the compact implantation setup AIDA (Advanced
Implantation Detector Array [17]), increasing the detection efficiency further to >60%.
With the production of more and more neutron-rich isotopes in and at the r-process region
it becomes important to be able to distinguish the measured β-delayed neutron events from
two- or even three-neutron emission events (see Fig. 24). Up to now only a few β-delayed
two-neutron emitters have been measured: 11 Li (t1/2 = 8.6 ms) [18], 30−32 Na (t1/2 = 1348 ms) [19], and the fission product 98 Rb (t1/2 = 114 ms) [20]. Additional candidates for
β-delayed two- and three-neutron emitters are 134 In and 135 In which can be measured
already now at existing facilities.
Funding
The Young Investigators group Dillmann is funded by the Helmholtz association via the
project VH-NG-627: ”LISA- Lifetime Spectroscopy for Astrophysics”.
[1] I. Dillmann and Y.A. Litvinov, Prog. Part. Nucl. Phys. 66, 358 (2011).
[2] R. L. Gill et al., Phys. Rev. Lett. 56, 1874 (1986).
NEUTRON DETECTION EFFICIENCY (%)
84
44
40
36
32
28
24
20
0.001
20 counters
30 counters
0.01
Monte Carlo
Simulations
0.1
1
5.5
ENERGY (MeV)
Figure 25: (Left) The BELEN neutron detector at Jyväskylä. (Right) Monte Carlo simulations of the neutron detection efficiencies for the previous setup with 20 3 He counters
and after the upgrade to 30 counters (both including the implantation detector SIMBA).
[3] K.-L. Kratz et al., Z. Phys. A 325, 489 (1986).
[4] I. Dillmann et al., Phys. Rev. Lett. 91, 162503 (2003).
[5] T. Ohnishi et al., J. Phys. Soc. Japan 79, 073201 (2010).
[6] H. Geissel et al., Nucl. Instr. and Meth. B70, 286 (1992).
[7] B. Franzke, Nucl. Instr. and Meth. B24/25, 18 (1987).
[8] B. Franzke, H. Geissel and G. Münzenberg, Mass Spectr. Reviews 27, 428 (2008).
[9] S.J. Steer et al., Phys. Rev. C 78, 061302(R) (2008).
[10] A. Morales et al., Acta Phys.Pol. B40, 867 (2009).
[11] F. Montes et al., GSI experiment proposal S323.
[12] J.L. Tain et al., GSI experiment proposal S410.
[13] K. Steiger, Diploma Thesis, Technische Universität München, Germany, (2009).
[14] C. Hinke, Ph.D. Thesis, Technische Universität München, Germany, (2010).
[15] M.B. Gomez Hornillos et al., Nucl. Instr. and Meth. A, in preparation.
[16] P. Möller et al., Phys. Rev. C 67, 055802 (2003).
[17] Advanced Implantation Detector Array, http://www2.ph.ed.ac.uk/ td/AIDA/welcome.html
[18] R. Azuma et al., Phys.Rev. Lett. 43, 1652 (1979).
[19] C. Detraz et al., Phys. Lett. 94 B, 307 (1980).
[20] P.L. Reeder et al., Phys. Rev. Lett. 47, 483 (1981).
85
1. I. Dillmann
LISA-Lifetime Spectroscopy for Astrophysics
MLL Accelerator seminar, Garching, 19.5.2010
Publications
1. Neutron capture cross sections of 184 W and 186 W
J. Marganiec, I. Dillmann, C. Domingo-Pardo et al.
Phys. Rev. C80, 025804 (2010)
2. Stellar (n,γ) cross section of p-process isotopes, Part 1: 102 Pd, 120 Te,
130,132 Ba, and 156 Dy
I. Dillmann, C. Domingo-Pardo, M. Heil, F. Käppeler, S. Walter, S. Dababneh, T.
Rauscher, F.-K. Thielemann
Phys. Rev. C 81, 015801 (2010)
3.
197 Au(n, γ)
cross section in the resonance region
C. Massimi et al. (The nTOF Collaboration)
Phys. Rev. C 81, 044616 (2010)
4. The 92 Zr(n, γ) reaction and its implications for stellar nucleosynthesis
G. Tagliente et al. (The nTOF Collaboration)
Phys. Rev. C 81, 055801 (2010)
5. Neutron physics of the Re/Os clock. I. Measurement of the (n, γ) cross
sections of 186,187,188 Os at the CERN n TOF facility
M. Mosconi et al. (The nTOF Collaboration)
Phys. Rev. C 82, 015802 (2010)
6. Neutron physics of the Re/Os clock. III. Resonance analyses and stellar
(n, γ) cross sections of 186,187,188 Os
K. Fujii et al. (The nTOF Collaboration)
Phys. Rev. C 82, 015804 (2010)
7. Neutron-induced fission cross section of 234 U and
CERN Neutron Time-of-Flight (n TOF) facility
C. Paradela et al. (The nTOF Collaboration)
Phys. Rev. C 82, 034601 (2010)
237 Np
measured at the
8. Stellar (n, γ) cross section of p-process isotopes, Part 2: 168 Yb, 180 W, 184 Os,
190 Pt, and 196 Hg
J. Marganiec, I. Dillmann, C. Domingo-Pardo, F. Käppeler, and S. Walter
86
Phys. Rev. C 82, 035806 (2010)
9. Solving the stellar 62 Ni problem with AMS
I. Dillmann, T. Faestermann, G. Korschinek, J. Lachner, M. Maiti, M. Poutivtsev, G.
Rugel, S. Walter, F. Käppeler, M. Erhard, A.R. Junghans, C. Nair, R. Schwengner,
A. Wagner
Nucl. Instr. Meth. B 268, 1283 (2010)
10. Highly sensitive AMS measurements of 53 Mn
M. Poutivtsev, I. Dillmann, T. Faestermann, et al.
Nucl. Instr. Meth. B 268, 756 (2010)
11. A new value for the half-life of 10 Be by Heavy-Ion Elastic Recoil Detection
and liquid scintillation counting
G. Korschinek, A. Bergmaier, T. Faestermann, et al.
Nucl. Instr. Meth. B 268, 187 (2010)
12. Preparation of a 60 Fe target for nuclear astrophysics experiments
D. Schumann, J. Neuhausen, I. Dillmann, et al.
Nucl. Instr. Meth. A 613, 347 (2010)
13. First Measurement of the 64 Ni(γ, n)63 Ni Cross Section
I. Dillmann et al.
Proceedings of Science, PoS(NIC XI)049 (2010)
14. The new p-process database of KADoNiS
T. Szücs, I. Dillmann, R. Plag, and Zs. Fülöp
Proceedings of Science, PoS(NIC XI)247 (2010) .
1. DPG Frühjahrstagung Bonn, 18.3.2010
I. Dillmann
First Experimental Constraints on the Stellar
63 Ni(n, γ)63 Ni
Cross Section
2. Nuclei in the Cosmos 11 (NIC-XI), Heidelberg, 21.7.2010
I. Dillmann
First Measurement of the 64 Ni(γ, n)64 Ni Cross Section
3. Nuclei in the Cosmos 11 (NIC-XI), Satellite Workshop ”Data Requirements in Nuclear Astrophysics”, Darmstadt, 26.7.2010
I. Dillmann
KADoNiS − The Karlsruhe Astrophysical Database of Nucleosynthesis in Stars
4. Int. School of Nuclear Physics (32nd Course), Erice/Italy, 20.9.2010
I. Dillmann
r-Process Nucleosynthesis: Future Experiments at the FRS and ESR
87
88
Group of Prof. Dr. Claudia Höhne (since 06/10)
Secretariat:
Anita Rühl (since 06/10)
Academic:
Prof. Dr. Claudia Höhne
Dr. Dmytro Kresan (since 08/10)
Dr. Tariq Mahmoud (since 12/10)
89
90
Development of a RICH detector for the CBM experiment
The CBM experiment
The CBM experiment will explore highly compressed baryonic matter in heavy-ion collisions from 8 – 45 AGeV beam energy at the future FAIR accelerator at Darmstadt [1].
The matter created in these collisions covers the intermediate range of the QCD phase
diagram. In this range, a phase transition between hadronic and partonic matter and
the onset of chiral symmetry restoration are expected. An experimental confirmation of
these phase boundaries would be of fundamental interest for a better understanding of the
strong interaction. Among the key observables to investigate these topics are low-mass
vector mesons and charmonium decaying into lepton pairs. As leptons leave the hot and
dense fireball without further strong interactions, their study will provide information on
in-medium properties of vector mesons, as well as on charm production and propagation
in hot and dense matter.
The CBM experiment will measure hadronic and leptonic probes with a wide phase space
acceptance. The core of CBM will be a silicon tracking system (STS) in a magnetic
dipole field for tracking and momentum information. This setup is followed by detectors
for particle identification: a RICH and a transition radiation detector (TRD) for electron
identification, a time-of-flight (TOF) wall for hadron identification, and an electromagnetic
calorimeter (ECAL) for the measurement of direct photons in selected regions of phase
space. In addition to the electron measurement, a setup with absorber-detector layers for
muon identification is under investigation.
The RICH detector
The RICH detector in CBM [2] is needed for an efficient and clean electron identification
for p ≤ 8 GeV/c in a wide phase space acceptance and with pion suppression in the order
of 500 - 1000. Specific challenges are posed by the fact that in the CBM experiment up
to 1000 charged particles per event at interaction rates up to 10 MHz are expected in
the detector acceptance for central Au+Au collisions if operated at the highest energies.
In order to cope with these challenges and specifications, we plan a vertically separated
RICH detector with CO2 as radiator gas (γth = 33, pth,π = 4.65 GeV/c) and PMTs with
fast, self-triggered readout electronics as photodetector.
The accessible wavelength range of Cherenkov photons in this design is limited by the
absorption of light in CO2 for λ / 175 nm. To project the Cherenkov light cones onto
the detector, spherical glass mirrors with a reflective Al+MgF2 coating are developed
in cooperation with industry. Al+MgF2 coatings typically show very good reflectivity
for λ ' 180 nm thus well matching the absorption edge in CO2 . In the detector plane,
PMTs will be used for photon detection. The Hamamatsu H8500 MAPMT is currently
the most promising candidate as it offers a good time resolution, a pixel size matching the
requirements of CBM, and convenient coverage of the photodetector plane of 2.4 m2 size
by approx. 55000 channels. The Hamamatsu H8500 MAPMT is offered with borosilicate
91
or UV enhanced window; the former one exhibits an absorption edge at λ ≈ 270 nm, the
latter one at λ ≈ 210 nm. In order to extend the sensitivity of the photodetector down to
the absorption edge of CO2 , we are re-investigating the usage of wavelength-shifting films
on top of the PMT windows.
With respect to the high interaction rates of up to 10 MHz and challenging triggers
in CBM, e.g. for open charm and charmonium measurements, we foresee self-triggered
readout electronics delivering the data with a precise time stamp to a large PC farm. On
this PC farm, online (partial) event reconstruction will allow to generate the required high
level trigger decisions.
CBM RICH prototype
A RICH prototype is being planned [3] by the CBM-RICH group in order to verify the
concept of the CBM RICH detector. This prototype will be scalable to the full CBM
RICH and results of the prototype test will be used to evaluate the simulations in the
CbmRoot framework including tests of ring finding and fitting algorithms on real data.
Concepts for the photodetector plane including the integration of readout electronics, and
mirror adjustment and alignment can also be tested. Finally, the results will provide all
necessary information for the Technical Design Report.
First tests are foreseen in October 2011 at the CERN PS at the T9 test-beamline. Here, a
secondary beam of hadrons and electrons with a momentum range of 1-10 GeV/c is available offering ideal conditions for understanding the electron-pion suppression capability of
the RICH detector in the relevant momentum range for CBM.
The layout of the RICH prototype has been developed at Gießen University; here the
prototype will also be assembled. The mechanical design of the prototype and the design of
the gas system are the responsibility of a group at PNPI Gatchina near St. Petersburg. The
photodetector plane and readout electronics are mainly developed by groups at University
Wuppertal and GSI. The mirrors including mounts are being worked out at the University
of Applied Sciences Esslingen, PNPI Gatchina and University Gießen. Colleagues from
Pusan Natl. University, Korea, will contribute to the slow control system and online
monitoring.
Design and Simulations According to the above requirements a prototype has been
designed. In order to have approximately the same amount of Cherenkov photons per
electron or pion track as for the CBM RICH, the length of the radiator (1.7 m) and the gas
type (CO2 ) were kept as in the layout of the CBM-RICH. The positioning and alignment
of the mirror and the photomultiplier (PMT) plane were adjusted to achieve focusing of
the light cone from Cherenkov radiation of an electron beam passing the detector.
A schematic view of the prototype layout is shown in Fig. 26. The illustration includes
the radiator (transparent yellow), the beam entrance window (left, red), the MAPMT
plane (green) and four rectangular mirrors (pink). The beam axis is shown in blue. The
transverse dimensions of the gas radiator are 1.2×1.2 m2 , its total length is 2.1 m.
92
Figure 26: Schematic drawing of the prototype geometry.
Figure 27: Left picture - distribution of the ellipse main axis versus momentum, right
picture - pion misidentification as a function of momentum.
In simulations, the beam conditions were included following the available characterization
from CERN; the beam in the simulation consists of 50% electrons and 50% negative pions.
In the event reconstruction the granularity of the photodetector is implemented as an
array of 4×4 MAPMTs with 64 channels each (1024 channels in total). Both, the signal
and additional noise hits were taken as input for the ring finding algorithm [4] based on
a standard implementation of the Hough transform finder in CbmRoot. Found rings are
then fitted as an ellipse to allow for ring distortions due to imperfect projection. The
Hough transform ring finding algorithm yields an electron ring reconstruction efficiency of
99.1%.
Applying a simple particle identification, a cut on the main axis a of the reconstructed
ellipse was used: Ellipses with a > 4.4 cm were identified as electrons, a < 4.4 cm as
pions. On average this yields a pion misidentification of 3.3%. Figure 27 shows the
93
distribution of the ellipse main axis versus momentum of the particle (left picture) and
pion misidentification as a function of momentum (right picture).
Based on this design in simulations a technical design is under development.
Figure 28: Proximity focusing setup with Plexiglas radiator (left) and quartz radiator with
pin hole mask (right).
Beamtest at CERN In November 2010 the CBM-RICH group together with other
CBM groups took part in a test beamtime at CERN PS target area T10 [5]. In particular
also prototypes of silicon tracking stations (STS) were tested which could be used for an
improved beam definition. The goal for this beamtime was to further study the Cherenkov
photon detection with Hamamatsu H8500 Multianode PMTs using a proximity focusing
test setup. This test provided valuable experience for the preparation of the fullscale gas
Cherenkov prototype setup described above.
The experiment was setup inside a light-tight box, similar to earlier tests at GSI [6].
This time, 4 MAPMTs were mounted in a L-shaped arrangement in front of a Cherenkov
radiator, covering roughly 25% of the generated Cherenkov cone (see fig. 28). Each pair
of two PMTs was connected via attenuator boards to individual nXYter Frontend boards
(FEB) each providing 128 readout channels. Two alternative kinds of radiator were used:
an 8 mm thick Plexiglas sheet, and a 4 mm thick quartz radiator. Both were oriented such
that the plane normal was pointing towards the PMTs in order to minimize ring distortion
due to refraction at the radiator surface.
Integrated hit distributions are shown in fig. 29. The time distribution of MAPMT hits
in relation to the trigger shows a clear coincidence peak with background below the peak
on the permille level. A cut on these coincident hits only is applied for all later analysis.
Data obtained with the Plexiglas radiator show a broad structure due to the large size of
the beam. Applying a coincidence condition on ≥ 1 hit in the STS limits the acceptance
range significantly and leads to a less smeared ring image as shown in fig. 29. Missing hits
in the upper left corner are caused by a broken cable. The hit multiplicity nicely reflects
a Poisson shaped distribution on some linear background. A χ2 -fit yields an average
multiplicity of 11-12 Cherenkov photons per event.
94
18
350
16
300
14
250
Events
Ypos (Pixel)
250
200
12
200
10
8
100
6
100
4
50
2
0
150
150
-5
0
5
10
15
Xpos (Pixel)
0
EPoisson= 11.7
50
0
0
2
4
6
8
10
12
14
16
18
Nr Photons/event
Figure 29: Integrated image of Cherenkov ring and hit multiplicity for data with Plexiglas
radiator including an additional cut on ≥1 hit in the STS.
This number has to be compared to the expected number of Cherenkov photons taking
into account all limiting factors as the finite transmittance of the radiators, the geometric
coverage of the MAPMTs, the wavelength dependent quantum efficiency of the MAPMTs,
and the geometrical acceptance of the photodetector. The number of photons detected by
the photodetector is then expected to be 9-10 for the Plexiglass radiator. This number is
significantly below the measured number per event which might be partly due to crosstalk
between neighboring pixels, an underestimation of the transmittance of Plexiglas for UV
photons, or an underestimation of noise. Anyway, the high photon yield shows the good
single photon detection capabilities of the H8500 PMTs. A full Monte Carlo simulation
of the setup is being prepared to further improve the quantitative understanding of the
data.
[1] C. Höhne, F. Rami, and P. Staszel, Nucl. Phys. News 16, 19 (2006).
[2] C. Höhne et al., Nucl. Instr. and Meth. A (2011), doi:10.1016/ j.nima.2010.10.062.
[3] D. Kresan and C. Höhne, CBM Progress Report 2010.
[4] S. Lebedev et al., J. Phys. Conf. Ser. 219, 032015, 2010.
[5] C. Pauly et al., CBM Progress Report 2010.
[6] J. Eschke and C. Höhne, Nucl. Instr. and Meth. A (2011), doi:10.1016/
j.nima.2010.10.104.
95
Publications
1. Fast parallel tracking algorithm for the muon detector of the CBM experiment at FAIR
A. Lebedev, C. Höhne, I. Kisel and G. Ososkov
Phys. Part. Nucl. Lett. 7, 291, (2010) .
2. Fast Parallel Ring Recognition Algorithm in the RICH Detector of the
CBM Experiment at FAIR
S. Lebedev, C. Höhne, I.Kisel and G. Ososkov
Proceedings of the ACAT 2010 conference, PoS (ACAT2010) 060 .
3. FAST PARALLELIZED TRACKING ALGORITHM FOR THE MUON
DETECTOR OF THE CBM EXPERIMENT AT FAIR
A.Lebedev, C.Höhne, I.Kisel and G.Ososkov
Proceedings of the ACAT 2010 conference, PoS (ACAT2010) 056 .
4. Fast Ring Recognition in the RICH detector of the CBM Experiment at
FAIR
S. Lebedev, C. Höhne and G. Ososkov
Proceedings of MMCP10, Bulletin of PFUR Series Mathematics, Information Sciences, Physics, number 2, (2010), 77 .
5. Fast Global Tracking for the CBM Experiment at FAIR
A. Lebedev, C. Höhne, I. Kisel and G. Ososkov
Proceedings of MMCP10, Bulletin of PFUR Series Mathematics, Information Sciences, Physics, number 2, (2010), 59 .
1. Workshop on Electromagnetic Probes of Strongly Interacting Matter,
ECT* Trento, Italien, September 2010
C. Höhne
Challenges for CBM: - in-medium modifications of vector mesons at high baryon
densities
2. 7th International workshop on RICH counters, Cassis (France) May 2010
C. Höhne
Development of a RICH detector for electron identification in CBM
3. DPG Frühjahrstagung Bonn, März 2010, Hauptvortrag
C. Höhne
Physik dichter Kernmaterie - von SPS zu FAIR
4. Strongly Interacting Matter under Extreme Conditions, Hirschegg Januar 2010
C. Höhne
Hadronic Matter at High Baryon Density

JLU - 2pi - Annual Report 2010 - Justus-Liebig

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