Neutron detection at DESPEC/FAIR

Transcription

Neutron detection at DESPEC/FAIR
D. Cano Ott
Nuclear Innovation – Nuclear Fission Division
D t off Energy
Dept.
E
CIEMAT, Instituto de Física Corpuscular, Universidad Politécnica de Cataluña (Spain)
LPC – Caen (France) – SPIRAL2/DESIR
L b t iN
Laboratori
Nazionali
i
li di L
Legnaro (It
(Italy)
l )
University of Jyvaskyla (Finland)
Laboratori Nazionali di Legnaro (Italy) – NEDA project SPIRAL2
University of Uppsala (Sweden) – NEDA project SPIRAL2
D. Cano-Ott, HISPEC/DESPEC meeting, March
Darmstadt
1st
and
2nd
Ciemat
Centro de Investigaciones
Energéticas, Medioambientales
y Tecnológicas
Neutron spectroscopy at DESPEC
GOAL: To measure neutron emission probabilities and energies for neutron
rich isotopes with relevance to basic nuclear physics, nuclear astrophysics
and nuclear technologies.
g
-High production: TOF spectrometer (in combination with a dedicated
gamma ray setup)
production and integral
g
values: 4π detector ((BELEN))
-Low p
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
BEta deLayEd Neutron detector for DESPEC/FAIR
• Measurement of delayed neutron emission probabilities Pn for
very neutron rich nuclei
• Nuclear structure of exotic nuclei and astrophysical r-process
r process
• High energy fission-fragmentation in-flight production +
Super-Fragment Separator for ion identification
• up to 44 ·He counters
60cm×∅2.5cm 20 atm
• 50cm×50cm×70cm PE
block
• ∅16cm hole for AIDA
implantation detector
• Triggerless
Ti
l
DACQ
DACQ:
independent (t,E) for every
counter, no ADC gate,
minimum dead time
time,
freedom to construct time
correlations
Proposal for a 1st experiment at GSI-FRS
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
Technical work for the neutron Time of Flight spectrometer
I. Develop the necessary Monte Carlo simulation tools. The efficiency of each detector has
t be
to
b validated
lid t d by
b Monte
M t Carlo
C l simulations.
i l ti
•Two main codes: MCNPX and GEANT4. MCPNX is used for general validation and
benchmarking. GEANT4 for realistic and complex simulations.
•GEANT4.
GEANT4. No access to the evaluated neutron cross section libraries (ENDF, JENDL,
JEFF…).
•Implementation of the light yield (for each material, various curves).
•Modelling of the light collection
II. Investigate the limits of each material and the best possible geometrical
configurations.
Time and energy resolution, lowest energy thresholds, neutron/gamma separation, light
collection -efficiency and homogeneity-, ideal geometry (not a unique solution)…
III. Evaluate the influence of the implantation setup on the degradation of the neutron
d t ti
detection.
Ti i
Timing,
material
t i l composition…
iti
IV. Develop the digital electronics.
Election of the optimal
p
sampling
p g rate / resolution / dynamic
y
range
g ((bits/MeV),reduce
),
the
noise…
V. Perform test measurements with well characterised beams
•Measurements
M
t with
ith reference
f
monochromatic
h
ti beams
b
(EU Metrology
M t l
L b PTB –
Lab
Braunschweig).
Medioambientales
st
nd
Ciemat
D. Cano-Ott,
HISPEC/DESPEC
meeting,
1 and 2 facility – JYFL) Energéticas,
•Simple physics cases
(experimental
program
atMarch
the IGISOL
y Tecnológicas
Darmstadt
Which material?
Plastics
Liquids
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
Does the use of C6D6 diminishes the crosscross-talk?
Simulation:
• cluster of 7 hexagonal detectors
• diameter: 15 cm
• length: 5 cm and 15 cm
• maximal illumination of central
detector
• source at 1 m
• neutron energies:
g
1 MeV and 5
MeV
J. Tain et al. – IFIC Valencia
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
Ratio of counts scattered to outer detectors respect to central
detector in the energy window [Emax/2,Emax]
En = 1 MeV
En
1 MeV
5 MeV
En = 5 MeV
5cm×∅15cm
BC501
C6D6
1.4%
2.5%
En
1 MeV
2.6%
3.5% meeting, March
5 MeV
D. Cano-Ott,
HISPEC/DESPEC
1st and 2nd
Darmstadt
15cm×∅15cm
BC501
C6D6
2.8%
5.6%
Ciemat
6.3%
Energéticas,
Medioambientales
10.4%
y Tecnológicas
The choice for DESPEC
The best (but still unsatisfactory) material for our purposes is still BC501A /
EJ301.
Adantages of BC501A:
-High
High light output.
-Best known neutron/gamma separation properties over all other liquid
scintillators(also at En< 1 MeV).
g scattering
g cross section).
)
-Intrinsic efficiencyy ((large
-Sensitivity to g-rays (low Z).
-Affordable price and better performance than compared to C6D6.
-Well characterised (compared to other materials).
Some of the drawbacks (compared to plastics):
-It is a liquid (has to be encapsulated).
-Toxicity and flammability (low flash point).
-More expensive.
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
n beam
BC501A
Ø20cmx5cm
Van de Graaff +
• Li(p,n)
(p, ) reaction,, En= 0.144,, 0.250,, 0.565,, 1.2,, 2.5 MeV,,
Cyclotron
•6 MeV, 8 MeV, 10 MeV, 14 MeV
• Pulsed beam (1.25MHz) for TOF background discrimination
• TOF measurement at L=1 - 2 m
Ciemat
D. Cano-Ott, with
HISPEC/DESPEC
meeting,
March 1 Na-22,
and 2
• Energy calibration
sources
(Cs-137,
Bi-207)
y Tecnológicas
Darmstadt
st
nd
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
The energy threshold
Detector
Material
Threshold
EDEN
NE213 (BC501A/EJ301)
En~200-300 keV
TONERRE
+ LEND (small plastics)
En~150 - 200 keV
BC408
En~50 keV
nELBE
EJ200
En~50 - 100 keV
DESPEC nTOF
BC501A
En~100
100 keV
nELBE plastic bar
DESPEC nTOF cell
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
liu
He
mf
lo w
p
Purification trap
2000
ΔM/M < 10-5
r
-o
n-
be
am
Fission
target
Nb
A = 101
Counts / frrequency
Detector tests:
Testing the detectors at the
University of Jyvaskyla cyclotron with
a pure 94Rb source.
IGISOL facility
Mo
1500
Analysing
magnet
Zr
1000
500
Y
0
1064700
1064800
Frequency Hz
1064900
Si 1
JYFLTRAP setup
ΔM/M < 10-6
7 T magnet
Precision trap
purification trap
precision
i i ttrap
+
Isobar spectrum of A=101
fission products measured
at spectroscopy setup
Si 2
microchannel
plate (MCP)
spectroscopic
D. Cano-Ott, HISPEC/DESPEC meeting, March 1st and 2nd
Darmstadt
Ciemat
setup
y Tecnológicas
Conceptual design of the spectrometer
The largest possible geometric effiency: 150 – 200 detectors (Consider the
combined use with the Ge detectors)
A reasonable intrinsic efficiency (i.e. detector thickness)
Reasonable energy resolution < 10% up to 5 MeV:
Good neutron timing ~1ns
Good β timing: <1ns
Resonable flight path 2-3 m TOF
Energy threshold ~ 100 keV En (10 keVee)
200 detectors, 10cm radius
TOF distance Geometric
(m)
efficiency
2
12 5%
12.5%
2.5
8.0%
3
5.6%
3.5
4.1%
4
3 1%
3.1%
4.5
2.5%
5
2.0%
ΔE/E @ 1 MeV
1ns
5ns
4.6%
4
6%
3.7%
3.1%
2.7%
2 3%
2.3%
2.1%
1.9%
16.4%
16
4%
13.2%
11%
9.4%
8 2%
8.2%
7.3%
6.6%
Darmstadt
Ø=20cm
L=5cm
1st
and
2nd
Ciemat
y Tecnológicas
CIEMAT’s high performance flash ADC
Resolution: 12 bits @ 1 Gsample/s or 14 bits @ 800 Msamples/s (1 GHz
bandwith) and 2 V p2p ADCs
FPGA for trigger decision and pre-processing.
DSP for pulse shape analysis.
2 Gbytes DDR2 for the storage of waveforms.
Trigger in/out, external clock synchronisation, various input ranges (500 mV- 12-5 V)
1.5 electronics engineers dedicated to the project fully + external support.
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
DDR2
External
Clock
Input
FPGA
FPGA
TDC
External
Trigger
DSP
ADC
Signal
Clock
D. Cano-Ott, HISPEC/DESPEC meeting, March 1
Input
Darmstadt Input
st
and
2nd
Signal
Ciemat
Input
y Tecnológicas
Summary and conclusions
•The design of the two neutron detectors for DESPEC is well advanced:
-A
A 4π long counter based on 3He detectors – BELEN.
BELEN Integral measurement of Pn
values. A version with 20 detectors is available and will be used at GSI.
-A neutron TOF spectrometer based on BC501A. Sensitive to En > 100 keV. Work
has been started for reaching
g lower values with alternative materials – 10B,, 6Li,,
Gd loaded detectors, maybe new materials (very interesting talk in the
scintillators session by Jarek Glodo RMD, Inc)?). Build a complementary
spectrometer
p
for low energy
gy neutrons.
•A large amount of work has been dedicated to update and set up adequate
Monte Carlo simulation tools: cross sections, light output, light collection…
•The liquid scintillator cell has been characterised with reference neutron beams.
•Pilot experiments have been carried out (or are accepted) at the Cyclotron
Laboratory of the University of Jyvaskyla (Finland).
•High
Hi h performance
f
di it l electronics
digital
l t i is
i being
b i designed
d i
d (prototypes
( t t
b i tested)
being
t t d)
for the nTOF spectrometer (and other detectors).
st
nd
D. Cano-Ott, HISPEC/DESPEC meeting, March 1 and 2
Darmstadt
Ciemat
y Tecnológicas
Future steps
•Test the new modified 5” Hamamatsu R877 fast PMT. Photonis is no longer
producing phototubes.
•Order 20 to 30 cells, depending on the $ to € conversion.
•Develop
D
l the
th nextt (close
( l
t final)
to
fi l) version
i off the
th digitisers
di iti
and
d integrate
i t
t them
th
i t
into
the DESPEC DAQ (help will be needed).
•Look for “innovative”
innovative solutions for the low energy neutron detectors (1 keV < En
< 100 keV): new materials (CLLC, CLYC…), new detector concepts.
•Perform test measurements at PRESPEC with AIDA (TOF resolution!!!).
resolution!!!) 1-2
12
days should be scheduled in the Umbrella proposal.
•Perform
Perform a read decay experiment at JYFL.
JYFL
•Prepare the TDR.
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
DESCANT
•
4 different shapes in 5 rings to achieve
close-packing
•
Front face located 50.0 cm downstream
from target
•
Maximum angle subtended of 65.5o
•
92.6% coverage of available solid angle or
1.08p sr
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
The VANDLE detector

(d,n
d,n)) Configuration
Geometry:

60 cm bars Æ 40 cm flight path

2 m bars Æ 1.5 m flight path
Properties

Energy Range: 100keV – 20MeV
Digital electronics Æ Low neutron
threshold
β-n Configuration
1 ns resolution Æ 70 keV@1 MeV
( 0 cm fflight path))
(40
β-n geometry coverage 4π; ndetection efficiencyy ~30%
%
Lab angle: 60-120°; lab resolution
1°
Darmstadt
1st
and
2nd
Ciemat
y Tecnológicas
The HRIBF digital beta-delayed neutron detector 3Hen
K. Rykaczewski (ORNL), R. Grzywacz, M. Madurga, D. Miller (UTK), E. Zganjar
((LSU),
) J. Winger,
g S. Ilyushkin
y
((Mississippi),
pp ) S. Liddick (NSCL,
(
UTK, UNIRIB),
) J.
Batchelder (UNIRIB)
PHYSICS :
new beta-delayed 1n and 2n emitters(T1/2,Ibn )
applied studies of low energy bn-emission
HRIBF, Long-counter, and NERO Neutron
Efficiency
seventy four 3He tubes detecting
neutrons in the 3He volume (f = 1”
and 2”, 24” long ,10 atm)
3He
H +n=p+t +0
0.75 M
MeV
V
High-Density Poly-Ethylene
moderator (LSU) MESYTEC
preamps (UTK),
(UTK) ISEG
ISEG-Wiener
Wi
HV
Pixie-16 digital data acquisition
Efficien
ncy (%)
100
80
60
40
20
0
0.001
st
D. Cano-Ott, HISPEC/DESPEC meeting, March 1 and
Darmstadt
HRIBF
long-counter
NERO
2nd
0.1
Ciemat
0.01
1
10
y Tecnológicas
Energy (MeV)