2+ - IPHC

Exo$c proton-­‐rich nuclei and connec$on to the Physics of X-­‐ray bursters David Jenkins Overview •  Lecture 1: X-­‐ray bursts – 
– 
– 
– 
Nuclear Physics involved Wai$ng points Why are there wai$ng points? How do we determine where the wai$ng points are? •  Lecture 2: Probing deeper –  Why is it hard to predict where the wai$ng points are? –  How do we address the structure of such exo$c nuclei on and beyond the line of N=Z X-­‐ray burst scenario Neutron stars: 10 km radius, 1.4 Mo, Normal star X-­‐ray burst scenario X-­‐ray burst Accre$on rate ~ 10-­‐8/10-­‐10 Mo/year Peak X-­‐ray burst temperature ~ 1.5 GK Recurrence rate ~ hours to days Neutron stars: 1.4 Mo, 10 km radius Dura$on of X-­‐ray burst: 10-­‐100 seconds Normal star Nuclear physics of x-­‐ray bursts During the thermonuclear runaway, heavier elements are created through a series of rapid proton-­‐capture reac$ons, termed the rp-­‐process. Z+1,N Other reac$ons compete with proton-­‐
capture during the process. Z Which reac$ons win? Z,N Z,N+1 N (p,γ) That depends upon the Q values, or (γ,p) how much energy can be released in β+ the reac$on. Proton-­‐capture reac$ons Photodisintegra$on Beta-­‐decay Astrophysical rp-­‐process From: www.nscl.msu.edu/research/ria/whitepaper.pdf Possible wai$ng-­‐point nuclides 66Se 67Se 68Se … rp-­‐process path (p,γ) (γ,p) Wai$ng-­‐point 65As 66As 64Ge 65Ge 67As 68As β+ In equilibrium: (p,γ) ↔ (γ,p) Process stalls un$l β-­‐decay 63Ga Z 62Zn 64Ga wai$ng-­‐point nuclide To determine equilibrium, need Qp 66Se 67Se 68Se … rp-­‐process path (p,γ) (γ,p) 65As 66As 67As β+ 68As −
Wai$ng-­‐point 64Ge 63Ga 65Ge 64Ga time − scale ∝
Q
kT
e
A(Q)
isotope production ∝ A(Q) ⋅ e
energy production ∝ A(Q) ⋅ Q ⋅ e
Z 62Zn Q
kT
Q
kT
Common parameter: Q (mass difference) Effec$ve life$me of the wai$ng-­‐point nuclide 68Se λ2 p ∝ exp{Q p kT }
λeffective = λβ + λ2 p
Dominated by β-­‐decay 100
t1/2, eff (68Se) (s)
10
uncertainty
in
t1/2,eff
Effect of proton capture 1
0.1
0.01
-1.5
-1
-0.5
0
0.5
Qp (68Se) (MeV)
G. Audi and A.H. Wapstra, Nucl. Phys. A595, 409 (1995). kT ~ 100 keV Precision required: < 100 keV (Δm/m < 1.5/106) Timescale X-­‐ray burst Wai$ng-­‐point nuclide 64Ge
68Se
72Kr
76Sr
Dura$on of X-­‐ray burst: 80Zr
β-­‐decay half-­‐life 63.7 s
35.5 s
17.2 s
8.9 s
4.6 s
10-­‐100 seconds The most important wai$ng-­‐point nuclides to inves$gate: 64Ge and 68Se Why are there wai$ng points? calculated staggering magnitudes for !CDE=Z are clearly
larger than the data, and the TDE values are close to the
Coulomb prediction but smaller by about 150 keV than the
experiment. In the JUN45 calculation, the INC interaction
is not included.
The underlying physics is that inclusion of the isovector
force in the f7=2 shell modifies interactions between the
tensor force makes pn more attractive than the average o
pp and nn, the last term in Eq. (3) becomes smaller, thu
increasing the TDE for A ¼ 42–54, as shown in Fig. 2(c
We note that the calculations do not support the apparen
change in the staggering phase at A ¼ 69 in the experi
mental !CDE. This may suggest [33] that the mass of 69 B
[16] was measured for an isomer, not for the ground state
GXPF1A JUN45 FIG. 3 (color online). Calculated one- and two-proton separation energies for odd-mass nuclei with isospin T ¼ 1=2, 3=2, 5=
and for even-mass nuclei with T ¼ 1, 2, 3 using the GXPF1A (left) and the JUN45 (right) interactions. In each box, the first numbe
denotes one-proton separation energy, and the second denotes two-proton separation energy. Thick (red) lines indicate the proto
drip line.
K. Kaneko et al., Phys. Rev. Lek.110, 172505 (2013) Shapes of N=Z nuclei Very Prolate
Oblate
Triaxial
Very, very sensi$ve to underlying quantum structure… The original phenomonological “M-­‐M” theory, (Microscopic Macroscopic) was very sound. The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your
computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.
P. Moller and J.R. Nix. At. Nuc. Data Tables, 26 (1981) 1965 S. Aberg. Phys Scr. 25 (1982) 23 W. Nazarewicz. Nucl. Phys A435 (1985) 397. R. Bengtsson. Conf on the structure in the zirconium region, 1988 {Classic “Poten$al Energy Surface” calcula$ons …. BUT The whole concept of isolated “shapes” is naive: there are mul$ple shapes with lots of mixing, as the barriers between shapes are not high. Shapes are hard to predict… The heart of the maker is the landscape……. How high is the barrier between shapes? How many minima? How much mixing? To answer these ques$ons needs more than just discovering the first levels. P. Moller, R.Bengtsson, B.G.Carlsson, P.Olivius, T.Ichikawa Phys.Rev.Lek. 97, 162502 (2006) 73Rb
69Kr
70Kr
71Kr
72Kr
69Br
70Br
71Br
68Se
69Se
70Se
(γ,p) (p,γ)
Dripline
(p,γ)
β
T1/2=35.5s
N=Z
How do we know 69Br and 73Rb are unbound? M.F. Mohar et al., Phys. Rev. Lek. 66, 1571 (1991) Isomers and fragmenta$on Fragmenta$on of 92Mo with γ detectors -1200
73
Rb
69
Br
-1000
9/2
+
t1/2(p)=3 ns
+
t1/2(p)
-
t1/2(p)
9/2
Qp (keV)
-800
-600
3/2
-400
-
3/2
t1/2(p)=233 ms
-200
C. Chandler et al., Phys. Rev. C 61, 044309 (2000) 0
D.G. Jenkins, Phys. Rev. C 78, 012801 (2008) How to determine where the wai$ng points are? The0ISOLTRAP0Experiment
M.'Mukherjee'et*al.,'Eur.'Phys.'J'A'35,'1'(2008)
R.'N.'Wolf'et*al.,'NIM'A'686,'82'(2012)
Detec-on0Principle
Charged"parNcle"stored"by"superposiNon"of"strong"
homogeneous"magneNc"field"in"z"direcNon"and"weak,"
electrostaNc"potenNal"for"axial"confinement
!
!
!
!
Frequency"measurement
Long"storage"Nmes
SinglePion"sensiNvity
High"precision
Frequency"measurement:"eigenmoNon"in"the"trap"can"be"
used"to"determine"mass
L.'S.'Brown'and'G.'Gabrielse','Rev.'Mod.'Phys.'58,'233'(1986)
13
B
The Canadian Penning Trap at ANL Savard, Clark et. al. Can directly measure masses at <100keV level v
B
+
-
+
Effec$ve life$me of the wai$ng-­‐point nuclide 64Ge 92
Aver all the data was carefully analyzed, ΔM = -­‐54344 (30) keV 91
Time of flight (µs)
90
89
88
87
100
86
10
85
1
84
-10
-5
0
5
10
Frequency applied - 1414335 Hz
Effec$ve stellar half-­‐life: 0.5 ≤ t1/2,eff(64Ge) ≤ 7 s 15
t1/2, eff (64Ge) (s)
-15
0.1
0.01
0.001
0.0001
0.00001
0.000001
-2
-1
0
1
64
Qp ( Ge) (MeV)
CPT - AME
CPT - FRDM
CPT - HF
SPEG - AME
AME: G. Audi et al., Nucl. Phys. A729, 337 (2003). FRDM: P. Möller et al., At. Data Nucl. Data Tables 59, 185 (1995). HF: B. A. Brown et al., Phys. Rev. C 65, 045802 (2002). SPEG: G.F. Lima et al., Phys. Rev. C 65, 044618 (2002). 2
Effec$ve life$me of the wai$ng-­‐point nuclide 64Ge Set up simple network code: 66Se 100
• Photodisintegra$on of 66Se, 65As (calculate new rates using results from CPT) • Beta decay of 64Ge, 65As, 66Se For each T, solve differen$al equa$ons describing abundances of 64Ge, 65As, 66Se. At peak temperature of 1.5 GK, effec$ve life$me of 64Ge ~ 0.7-­‐35 s. Effective stellar half-life (s)
• Proton capture on 64Ge, 65As 10
1
65As 66As 64Ge 1
1.5Ge 0.1
0.01
0.5
65
2
2.5
Tem perature (GK)
Red lines delineate the range allowed by the 1995 AME. Black lines delineate the range 64aGa llowed with CPT result. Timescale of rp-­‐process s$ll dominated by uncertain$es at the wai$ng-­‐point 64Ge due to the large uncertainty in the 65As mass 68
Resonance obtained for Se 200 ms excita$on 112
110
FWHM ~ 5 Hz ~ 250 keV TOF (arbitrary units)
108
106
104
102
100
98
96
94
92
90
88
-15
-10
-5
0
5
10
Frequency applied - 1331060 Hz
With all data collected, ΔM = -­‐54232 (19) keV 15
How does this compare to other techniques and theory? Mass excess (MeV)
-52.0
-52.5
-53.0
-53.5
-54.0
-54.5
-55.0
FRDM
1995 AME
SPEG
CSS2
(2003)
FMA
FRDM: P. Möller et al., At. Data Nucl. Data Tables 59, 185 (1995). 1995 AME:
G. Audi and A.H. Wapstra, Nucl. Phys. A595, 409 (1995). SPEG:
G.F. Lima et al., Phys. Rev. C 65, 044618 (2002). CSS2:
M. Char$er et al., J. Phys. G 31, S1771 (2005). FMA:
A Wöhr et al., Nucl. Phys. A742, 349 (2004). CPT:
J.A. Clark et al., Phys. Rev. Lek. 92, 192501 (2004). CPT
Effec$ve life$me of the wai$ng-­‐point nuclide 68Se 100
t1/2, eff (68Se) (s)
10
1
0.1
0.01
-1.5
-0.5
0.5
1.5
68
Qp ( Se) (MeV)
CPT - AME
SPEG - AME
Pfaff et al.
Contribu$on of 68Se to the $mescale of the rp-­‐process ~ 32 seconds. CSS2 - AME
FMA -AME
CPT - HF
CPT: J.A. Clark et al., Phys. Rev. Lek. 92, 192501 (2004). AME: G. Audi et al., Nucl. Phys. A729, 337 (2003). SPEG: G.F. Lima et al., Phys. Rev. C 65, 044618 (2002). Pfaff: R. Pfaff et al., Phys. Rev. C 53, 1753 (1996). CSS2: M. Char$er et al., J. Phys. G 31, S1771 (2005). FMA: A. Wöhr et al., Nucl. Phys. A742, 349 (2004). HF: B. A. Brown et al., Phys. Rev. C 65, 045802 (2002). Se [23] and of Se [24] using the Low Energy Beam and
Ion Trap (LEBIT) high-precision Penning trap facility [25]
have reduced the uncertainties in the masses to negligible
ending
values
1.5
respectively.24week
Combining
them
PHY
S I C A L of
RE
V I EkeV
W Land
E T T E5RkeV,
S
JUNE 2011
PRL 106, 252503 (2011)
with a calculation of the CDE [26] yielded an estimated
of Implications
Sp ¼ "636ð105Þ
whereRapid
the uncertainty is
Ground-State Proton Decay value
of 69 Br and
for the 68 SekeV
Astrophysical
Proton-Capture Process Waiting Point
dominated by the estimated contributions from the theo*
M. A. Famiano, retical
A. M. Rogers,
W. G. Lynch,
S. Wallace, F. Amorini, D. Bazin, R. J. Charity,
CDEM.predictions.
F. Delaunay, R. T. de Souza, J. Elson, A. Gade, D. Galaviz, M.-J. van Goethem, S. Hudan, J. Lee,
In this
Letter,H. we
report
on theL. G.first
direct measurement
S. Lobastov, S. Lukyanov, M. Matoš,
M. Mocko,
Schatz,
D. Shapira,
Sobotka,
week
ending
69
M.
Tsang, and G. Verde
ground-state
decay
from
Br. This result
P H Y S I C A L Rof
EV
IB.
EW
L E T T E Rone-proton
S
24 JUNE 2011
PRL 106, 252503 (2011) National Superconducting
Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
Physics Division, Argonne
National Laboratory,
Argonne, Illinois,
60439 USA
accurately
constrains
the 2p-capture
branch of the astro22
Experiment
Physics
GrantEastNo.
DE-FG02-87ER-40316
and
Joint Institute of Nuclear Astrophysics,Nuclear
Michigan State
University,
Lansing,
Michigan 48824, USA
20
68
waiting
Simulation (Mirror)
Department of Physics, physical
WesternContract
Michiganrp-process
University,
Kalamazoo, Se
Michigan
49008, USA point to be <0:25%
No.
DE-AC02-06CH11357.
18
Simulation (9/2+ g.s.) Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
(within
1!),
which
sufficient
16
Los Alamos National
Laboratory,
Los Alamos,
New is
Mexico
87545, USA to demonstrate that it can
Istituto
Nazionale
di
Fisica
Nucleare,
Laboratori
Nazionali
del
Sud,
Catania,
Italy
14
be neglected in present type II-95123,
x-ray
burst models.
Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA
1,2,3,
4,3
9
10
12
1,5,3
8
12
6
1,5
7
1,3
1,3
6
1,5,3
1
1
11
8
10
13
1
8
14
1
2
3
4
5
8
12
9
LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen, France
*amrogers@phy.anl.gov
Indiana University Cyclotron Facility and Department
of Chemistry, Bloomington, Indiana 47405, USA
11
Kernfysisch Versneller Instituut,
Groningen,
Netherlands
[1] R.NL-9747
K. Wallace
and S. E. The
Woosley,
Astrophys. J. Suppl. Ser.
1500 Moscow AA
12
Theory
FLNR/JINR, 141980 Dubna,
region, Russian Federation
45,
389
(1981).
13
Oak Ridge National Laboratory,
Oak Ridge,
37831,
USA
Indirect
[2] H. Schatz
et al.,Tennessee
Phys. Rep.
294,
167 (1998).
14
1000
Istituto Nazionale di Fisica Nucleare,
Sezione di Catania, Catania, I-95123, Italy
Systematics
[3] H. Schatz and K. E. Rehm, Nucl. Phys. A777, 601 (2006).
(Received 17 December 2010; published 24 June 2011)
10
0.4
[4] W. H. G. Lewin and M. van der Klis, Compact Stellar
Experiment
We report
the first
of the proton
separation
energyUniversity
for the proton-unbound
0.6
0.8
1.0 on1.2
1.4direct measurement
500X-ray
(This work)
Sources
(Cambridge
Press, Cambridge,
69
68
nucleus
Br.
Bypassing
the
Se
waiting
point
in
the
rp
process
is
directly
related
to the 2p-capture rate
Q Value [MeV]
England, 2006).
through 69 Br, which depends exponentially on the proton separation energy. We find a proton separation
[5] 0B. S. Dzhelepov, SSSR Ser. Fiz. 15, 496 (1951).
Br of aSp69
ð69Se
BrÞmirror
¼ $785þ34
this is less bound compared to previous predictions which
energy
for 69from
$40 keV;
FIG. 5. Comparison of the best-fit
results
[6] Y. B. Zel’dovich, Sov. Phys. JETP 11 (1960).
have
relied
on
uncertain
theoretical
calculations.
The influence of the extracted proton separation energy on
level ordered simulation to the experimental data.
[7] isV.examined
I. Goldansky,
Nucl. Phys. 19, 482 (1960).
the rp process occurring in type I x-ray bursts
within the context of a one-zone burst model.
-500
Savory [24]
0.2
AME03 [28]
0.0
Lima [20]
2
Ormand [18]
6
4
AME95 [27]
8
Brown [26]
[8] B. Blank et al., Prog. Part. Nucl. Phys. 60, 403 (2008).
Wohr [21]
Clark [22]
Pfaff [16]
the ground state in experimentsDOI:
relying
on the short life10.1103/PhysRevLett.106.252503
PACS numbers:
21.10.Dr,
27.50.+e
[9] S. Hofmann
et al., Z.
Phys. 23.50.+z,
A 305, 26.30.Ca,
111 (1982).
þ
[10]
D.
F.
Geesaman
et
al.,
Phys.
Rev.
C
15,
1835
(1977).
-1000
time [42]. Assuming Masses
the observed
peak
to
be
the
9=2
long 35.5 s half-life of 68 Se, compared to the time scale
and decay properties of many nuclei along the
[11]
J.
Giovinazzo
et
al.,
Phys.
Rev.
Lett.
89,
102501
level with a pure ‘ ¼
4 transition,
we have
of a typical x-ray burst (& 10–100 s), and its(2002).
location on
proton
drip line play
a keysimulated
role in the this
rapid proton- (rp)
[12]
E.
Hourani
et al., Z.
334, 277limit
(1989).
possibility as the dotted
line
in Fig.
Our simulation
of [1]).-1500
the proton
dripPhys.
line Aseverely
further progression
capture
process
(see5. Wallace
and Woosley
The rp
[13] J. D. Robertson
et masses.
al., Phys.It Rev.
42, 1922
(1990).
to heavier
has Cbeen
shown,
however, that2010
process
consists of tail
sequences
1995
2000
2005
the assignment displays
a low-energy
causedofbyfast
theproton-capture
[14]
M. F. Mohar
et al.,reactions
Phys. Rev.
Lett. 66,
1571 (1991).
2p-capture
through
unbound
nuclei
such as
reactions
on
proton-rich
nuclei
near
the
proton
drip
line
long lifetime that is inconsistent with the data.
Moreover, if
Year
69 et al., Phys. Rev. Lett. 74,
þ decays. When the reaction
[15]
B.
Blank
4611
(1995).
Br
can
bypass
key
waiting
points
if
these
nuclei
are
flow
and
their
subsequent
!
a spin-parity of 9=2þ is assigned to the observed peak,
[16]
R.
Pfaff
et
al.,
Phys.
Rev.
C
53,
1753
(1996).
only
slightly
unbound
[2].
Figure
1
illustrates
a
possible
reaches weakly bound nuclei at the proton drip line, further
then the CDE extracted from our measurement for this
et al., Nucl.
Phys.
(1992). the 68 Se waiting
[17] P. Möller
rp-process
reaction
pathA536,
which61bypasses
2p Flow
10
Sp (69Br) [keV]
Counts / 83 keV
6
7
30%
10%
3%
1%
0.3%
PHYSICAL REVIEW C 84, 051306(R) (2011)
69
Kr β-delayed proton emission: A Trojan horse for studying states in proton-unbound 69 Br
A. M. Rogers,1,* J. Giovinazzo,2 C. J. Lister,1 B. Blank,2 G. Canchel,2 J. A. Clark,1 G. de France,3 S. Grévy,3 S. Gros,1
E. A. McCutchan,1 F. de Oliveira Santos,3 G. Savard,1 D. Seweryniak,1 I. Stefan,3 and J.-C. Thomas3
1
2
Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
Centre d’Etudes Nucléaires de Bordeaux Gradignan,Université Bordeaux 1, UMR 5797 CNRS/IN2P3, Chemin du Solarium, BP 120,
F-33175 Gradignan Cedex, France
3
Grand Accélérateur
d’Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, F-14076 Caen, France
RAPIDNational
COMMUNICATIONS
(Received 25 August 2011; published 16 November 2011)
PHYSICAL REVIEW C 84, 051306(R) (2011)
Particle decay of 69 Br and 65 As was observed through β-delayed proton emission of 69 Kr and 65 Se, respectively.
Decay spectroscopy was performed through β-p correlations using a position-sensitive silicon-implantation
detector surrounded by a γ -ray detector array. A β-decay half-life of 27(3) ms was measured for 69 Kr and
33(4) ms for 65 Se. The 69 Kr ground state decays by a superallowed transition to its unbound isobaric analog state
RAPID COMMUNICATIONS
in 69 Br which immediately decays by a 2.97(5)-MeV proton group to the first excited state in 68 Se at 854.2 keV.
This chain of decays constrains both the mass and spin of the 69 Kr ground state. We observed no evidence of
PHYSICAL REVIEW C 84, 051306(R) (2011)
Br.ROGERS et al.
ground-state proton decay fromA.69M.
DOI: 10.1103/PhysRevC.84.051306
PACS number(s): 23.40.−s, 23.50.+z, 27.50.+e, 26.30.Ca
Counts / 50 keV
Proton-Detection Efficiency (%)
Beyond determining the limits of existence of very neutronthrough indirect techniques or through direct observations
deficient nuclei between nickel and tin, slow progress has been
immediately following 69 Br production using in-flight decay
made in the spectroscopy of exotic nuclei with N < Z, that is,
[2]. Initial searches attempted to produce 69 Br through fusionRAPID COMMUNICATIO
nuclei with negative Tz , in this region. This is unfortunate, as
evaporation reactions [4] and 78 Kr projectile fragmentation,
these nuclei and their decays are critical in understanding the
leading to a lifetime upper limit of 24 ns [3,5]. The first direct
A. M. ROGERS
et al.key information
PHYSICAL
REVIEW C 84, 051306(R) (2011)
rapid-proton capture (rp) process,
providing
measurement of 69 Br ground-state proton decay,
reconstructed
for testing the CVC hypothesis, exploring the breakdown of
from the breakup into p + 68 Se, found 69 Br to be unbound by
mirror
symmetry
due to Coulomb
effects and poor binding,
785+34
5
FIG. 2. (Color online)
Partial
particle-identification
−40 keV [2].
100spectrum
14
andinyielding
stringent
tests of contemporary
nuclear-structure
for implanted heavy ions
the DSSD.
The energy-loss
signal is
Similar complications exist for 65 As. Compared to 69 Br, 4
90
+110
65
3
models.
measured by the silicon
#E detector while the RF, gated on the
As is considerably longer lived
12 (t1/2 = 190−70 ms) [6]. It
2
80
additional timing signals, measures
heavy-ion TOF.
Particles
Recently,theconsiderable
progress
hasare
been made concerning
still, however, lies near the proton
andPartial
is difficult
FIG. 2.drip
(Colorline
online)
particle-identification spectrum
1
64
68
.
separated based on theirthe
charge,
Z,
and
isospin,
T
astrophysical aspect:z For both
Se(Color
rp-process
70 the Ge and
for10
implanted
heavy for
ions measurement
in the DSSD. The energy-loss signal is
to produce
in sufficient
required
FIG. 1.
online) Schematic
of the implant-decay
station.quantities
65 by the silicon #E detector while 700
measured
RF, gated
on 900
the 950
800 850
Proton-rich nuclei implanted
DSSD
decay
and
are
correlated
“waiting points,” measurements60of their proton-unbound
pre- into the
in a Penning trap. Recently, the As ground-state mass was the 750
additional
timing signals, measures the heavy-ion TOF. Particles
are
65
69
with
β and
pthe
decay
products
as well as coincident γ rays measured
8
E
(keV)
cursors,
As
and
Br,
have
been
reported
[1,2].
In
case
of
events and are removed by subtracting uncorrelated events in in the surrounding HpGe array. Energy
determined
by a storage-ringseparated
lifetime
measurement
[1].
based
on their charge, Z,
andThe
isospin, Tz .
loss and timing signals were
50
64
68
Gewindow
the waiting
in from
Setheit first
likely
the latter half of the time
[12].point is likely bypassed, while
inferred
decay
Qp value
generated
silicon #E
detector with
additional
time-of-is so low,
6 90(80) keV, that sequential
65
40spectroscopic
is not.into
Interest,
however,
in the
and structural
measured using2p
two upstream
Heavy ions implanted
the DSSD,
corresponding
to flight information
events and are removed
by subtracting
As significantly
bypasses
the 64 Geuncorrelated events in
capturemicrochannel
through plate
detectors
the 4
latter half
of the timeenvironment.
window [12].
properties
these nuclei
remains.
We report
on(not
theshown).
decay of
30 where
triggers in the #E detector,
wereof
identified
via #E-TOF
waiting-point nucleus in the explosive
rp-process
65
65
Heavy ions implanted into the DSSD, corresponding to
Se and 69
Kr intothe
their
proton-unbound
the redundant TOF information
reduced
backgrounds
The only spectroscopic information
comes
from β-decay data via #E-TOF where
20 in the daughters As and
triggers
#E detector, were identified
69
65
65
2 in the
Br. TheseDSSD
parentstriggered
are relatively
long-lived,
∼30 ms, allowing
particle-identification spectrum.
events,
with- degrader
where
Se
was
reported
to
decay
to
the
IAS in its
Asthe backgrounds in the
the redundant TOF information
reduced
at the intermediate focal plane and transported to an
10
them to to
bedecay
cleanly
separated,
and implanted
a enddaughter
out a #E signal, correspond
events.
A set transported,
of parallel implantation
followed
an observed
3.55(3)MeVspectrum.
proton-decay
particle-identification
DSSD triggered events, withstation in
at the
of the LISE3
beamline.by
Time0
0 decay,
64
out[7].
a 0#E signal,
correspond
events. A
set of parallel
decay
wheresettings
the nuclei
β
populating
of
electronics utilizing low
andstation
high gain
digitized
(TOF)
and energy-loss
(#E)
measurements
allowed
1000
2000to decay
3000
4000
5000
6000
the
Ge
state
0 the
1 of-flight
2
3 states
4
5
6group
7 to
8
9 ground
10
electronics
utilizing
low
and
high
gain
settings
digitized the
event-by-event
fragment
identification.
Decay
spectroscopy
Decay
Energy
(keV)
interest in
their and
short-lived
daughter
nuclei.
TheProton
original
goal
DSSD high-energy implant
events
lower-energy
decay
Because of the additional binding due to pairing for
Energy (MeV)
DSSD high-energy implant events and lower-energy decay
performed
on fragments
implanted into a double-sided
was to
observe the
Kr β-decayusing
strength
bypassed
the
events. A proton energy
calibration
was69performed
a wasthat
even-Z
nuclei, the proton events.
drip line
extends
out farther
proton
energy
calibration
was performed
using
strip detector (DSSD), correlated with β-delayed protons.
FIG. 8.A Charged
particle
decay-energy
spectrum
for atime corre69
239
241
244
FIG.
6.Cm.
Proton-detection
efficiency
as a function lifetimes
244
isobaric
andand
fed the
Br ground state,
where in the
triple-α source containing
linesanalog
from state
Pu,(IAS)
Am,
and,DSSD
correspondingly,
are longer for proton-rich 239
Kr 241
Exo$c proton-­‐rich nuclei and connec$on to the Physics of X-­‐ray bursters Lecture 2: Probing deeper into the nuclear structure David Jenkins Overview •  Lecture 1: X-­‐ray bursts – 
– 
– 
– 
Nuclear Physics involved Wai$ng points Why are there wai$ng points? How do we determine where the wai$ng points are? •  Lecture 2: Probing deeper –  Why is it hard to predict where the wai$ng points are? –  How do we address the structure of such exo$c nuclei on and beyond the line of N=Z Shapes are hard to predict… The heart of the maker is the landscape……. How high is the barrier between shapes? How many minima? How much mixing? To answer these ques$ons needs more than just discovering the first levels. P. Moller, R.Bengtsson, B.G.Carlsson, P.Olivius, T.Ichikawa Phys.Rev.Lek. 97, 162502 (2006) C.J. Lister et al., Phys. Rev. 42, R1191 (1990) Other evidence for shape coexistence Jπ=0+ is first excited state, so NO g-decay, just E0
Isomer found in fragmentation at GANIL. When fully stripped the isomer lifetime
becomes very long as it can only decay by two-photon emission or higher order.
E. Bouchez, et. al., Phys. Rev. Lett. 90 (2003) 082502
Reorienta$on in Coulomb excita$on p Shape coexistence in mean-­‐field models: Skyrme M. Bender, P. Bonche and P.H. Heenen Phys Rev C74 (2006) 024312 HFB+GCM method Skyrme SLy6 force density dependent pairing interacYon B(E2) values e2fm4 Restricted to axial symmetry : no K=2 states Shape coexistence in mean-­‐field models: Gogny J-­‐P. Delaroche et al. HFB+GCM with Gaussian overlap approximaYon Gogny D1S force Axial and triaxial degrees of freedom B(E2) values e2fm4 Which nucleus has “best” shape co-­‐existence? Theory says 72Kr, but experiment points at 68Se…..but the differences are subtle and a reflec$on of our advanced understanding P. Moller, R.Bengtsson, B.G.Carlsson, P.Olivius, T.Ichikawa Phys.Rev.Lek. 97, 162502 (2006) True collec$ve oblate rota$on? Certainly, the 68Se g.s.b. has a level sequence which appears to have a small (and smooth) moment of iner$a consistent with classical oblate collec$vity S.M. Fischer et. al. Phys. Rev. Lett. 84 (2000) 4064
70Se12C16O
⇒ 98 a.m.u.
Isobaric contaminants ⇒ A = 98
Break up 70SeCO inside EBIS
and charge breed up to a q = 19+ charge
state (A/q ~ 3.68)
⇒ eliminates isobars!
REX-ISOLDE ⇒ ε ~ 2.4%
⇒ Ib(70Se) ~ 1.4 x 104 delivered to MB
target
104Pd(70Se,70Se) @ 2.94 MeV/u “normal kinemaYcs” MINIBALL array Miniball is purpose-­‐built for detec$on of low mul$plicity gamma rays with high efficiency Segmented detectors and on-­‐board pulse shape analysis are employed to locate point of first interac$on to give superior Doppler correc$on Par$cle Detec$on The scakered projec$les and/or recoiling target nuclei are detected in a CD detector which subtends angles of around 10-­‐50o • 
• 
• 
• 
• 
• 
Total area = 50 cm2 (93% ac$ve) 16 annular p+ strips/quadrant 24 sector n+ strips/quadrant Total of 160 discrete detectors Wafer thickness 35 -­‐ 1000 μm ΔE-­‐E moun$ng Coulomb excitaYon of 70Se A shape study of 72Kr (2+)
- a rarity that gives a deeper understanding of effective nucleon-nucleon interaction
IS478 Spokesperson – B.S. Nara Singh,
http://isolde.web.cern.ch/sites/isolde.web.cern.ch/files/April%202013.pdf
~ 28 % effect
Energy (Arb.)
Energy vs Strip No. Strip
CD gated gamma spectra
Doppler Corrected for
104Pd target excitation,
~ 430 counts
Doppler Corrected for
72Kr projectile excitation:
~180 counts in 710 keV line
104Pd
72Kr
Structure at the proton-­‐rich limits The region of interest Isospin symmetry
Shape-coexistence
rp-process
56 56
Recoil-­‐decay tagging Euroschool Piaski, September 2008 57 Recoil-­‐beta tagging Euroschool Piaski, September 2008 58 Recoil separators RITU (Jyvaskyla) FMA (Argonne) Euroschool Piaski, September 2008 59 RDT Instrumentation at JYFL
JURO
GREAT
Focal plane
spectrometer
GAM
RITU
r
oil separato
c
re
d
le
il
-f
s
Ga
n 20-50 %
Transmissio
TDR
Euroschool Piaski, September 2008 Total Data Readout
Triggerless data acquisition system
with 10 ns time stamping 60 RITU+GREAT Euroschool Piaski, September 2008 61 Euroschool Piaski, September 2008 62 TDR : Total Data Readout
• 
• 
• 
• 
• 
• 
Triggerless Data Acquisi$on System Rates up to 850 kHz without dead$me 380 channels $mestamped data 10 ns resolu$on Time-­‐of-­‐Day clock with 32 day rollover Flexible + Easily Scalable Euroschool Piaski, September 2008 63 74
Test case: Rb Euroschool Piaski, September 2008 64 Proof-­‐of-­‐principle • 
• 
• 
• 
• 
natCa (36Ar, pn) 74Rb Ebeam = 103 MeV τ½ (74Rb) = 65 ms β+endpoint ~ 10 MeV σ ~ 10 µb Euroschool Piaski, September 2008 65 High energy positrons Euroschool Piaski, September 2008 66 Euroschool Piaski, September 2008 67 Varying the beta gate size 1 10 MeV 3 10 MeV 6 10 MeV Euroschool Piaski, September 2008 68 74
Iden$fica$on of Rb A.N. Steer, et al., NIM A565, 630 (2006) Euroschool Piaski, September 2008 69 74Rb level scheme from RBT
Euroschool Piaski, September 2008 70 78
Unknown case: Y •  Nothing known about 78Y except 0+ superallowed decay and (5+) beta-­‐decaying isomer •  RBT technique applied using 40Ca(40Ca,pn)78Y reac$on •  Cross-­‐sec$on should be very similar to 74Rb •  90% of flux proceeds to low-­‐lying isomer •  Isomer is too long-­‐lived for effec$ve tagging Euroschool Piaski, September 2008 71 Euroschool Piaski, September 2008 72 New DSSD
•  As RITU is designed to operate on heavy mass regions, recoil separa$on is not anymore op$mal in the A~70 region. •  Recoil distribu$on is focused on the right hand side of the DSSD (beam and scakered components follow closely the recoil distribu$on so it can not be centered). •  8 kHz rate is impinged only on the half of the ac$ve area of the DSSD which in turn increases risk of random correla$ons! •  Device was tested with 28Si + 40Ca reac$on at Eb=75 MeV with various different beam intensi$es (simultaneously with phoswich or planar ge set-­‐
up). New DSSD design Recoil map from the (old) GREAT DSSD •  Only right hand side works as an ac$ve detector. •  Consists of 120 x 80 strips with strip pitch of 0.480 mm •  500 mm thick •  In total ~10000 pixels! •  -­‐> 0.8 Hz recoil rate / pixel. Slides from Panu Ruotsalainen Phoswich scintillator
•  High/low energy beta-­‐par$cle detec$on and discrimina$on: Direct energy & full pile-­‐up discrimina$o
•  Beta/gamma discrimina$on
•  Discrimina$ons can be done on the basis of pulse shape analysis. 3 x PMT (Hamamatsu, 10 dynode stages) Scin$llator head Light-­‐guide BC-­‐404 (”fast”) d = 10 mm Beta-­‐par$cles •  BC-­‐404: rise $me ~ 0.7 ns, decay $me ~ 1.8 ns, light output 68 % of anthracene •  BC-­‐444: rise $me ~ 19.5 ns, decay $me ~ 285 ns, light output 41 % of anthracene BC-­‐444 (”slow”) d = 31.5 mm Phoswich scintillator
•  Traces were recorded from Lyrtech ADCs. •  Pulse shapes were categorized online by rudimentary algorithm. •  On the basis of online analysis, device works and can be u$lized for tagging purposes! •  We s$ll need to resolve the possible gain in data quality… Combined pulse shapes (high E betas) Beta-­‐tagged JUROGAM II gammas Fa
) mmas
a
g
d
n
s a
E beta
w
o
l
(
st only
UoY •  Designed to suppress events associated with cp evapora$on channels. •  Consists of 96 20 x 20 mm CsI crystals (Hamamatsu) divided into 6 flanges (8 x 2 crystals in each flange). •  Signal chain: Mesytech preamplifiers -­‐> ”GO-­‐
box” -­‐> Lyrtech ADCs. •  Measured detec$on efficiency for 1 charged par$cle is 80-­‐90 %. RITU LISA chamber JurogamII UoY Comparison of recoil gated (blue curve) and raw UoYTube (light blue) spectra from 28Si + 40Ca reac$on. ~40o ~60o Evaporated par$cles from O and C reac$ons (Ca-­‐target gets oxidized easily.) …scakered O and C. Measured distribu$on of evaporated par$cles in 28Si + 40Ca reac$on. Simulated distribu$on of evaporated par$cles in 40Ca + 40Ca reac$on (J. Saren) . UoY •  Test was performed in August 2011 (~50 hours beam on target w/ various Ib).
•  Reac$on of 28Si + 40Ca was u$lized at Eb=75 MeV to populate excited states in 66Se via 2n evapora$on channel. •  This was good test case as the 2+ -­‐> 0+ transi$on in 66Se has been recently iden$fied by A. Obertelli. Beta tagged JUROGAM II spectra all recoils recoils w/ 0 cp @ UoYTube Counts / keV
2
Counts
20
10
10
8
6
4
2
0
3
Counts / keV
1
10
0
0
1
2
3
4
Log( t)
5
6
7
8
2.5
2
1.5
1
0.5
5
0
5
0
0
100
200
300
400
500
600
t (ms)
700
800
900
1000
Counts / keV
Counts / 5 ms
Counts / keV
25
15
30
0
12
3
20
40
4
3
2
1
0
400
420
440
460
480
500
520
Energy (keV)
540
560
580
600