Transcript 1. dia - SLCJ, Cyklotron Warszawski

The DIAMANT light-charged particle detector:
Performance and plans for improvements
Barna M. Nyakó
B.M. Nyakó (ATOMKI)
Workshop on NWall at GANIL …
4-5 Oct. 2007. HIL, Warsaw
The DIAMANT collaboration
CENBG (Bordeaux) – ATOMKI (Debrecen) – University of Napoli
J.N. Scheurer et al.
B.M. Nyakó et al.
G. la Rana et al.
Recently extended by: iThemba LABS (Cape Town)
S.M. Mullins et al.
DIAMANT is a high-granularity, 4π light charged-particle detector
array [1] of CsI(Tl) scintillators, used as ancillary device in large
gamma-ray spectrometers to discriminate xnγ & particle-xnγ data
by vetoing or gating on emitted light charged particles.
Signal processing: realized in VXI standard [2].
Contact persons: B.M. Nyakóa, J.N. Scheurerb
a) Institute
of Nuclear Research, (ATOMKI), Debrecen, Hungary; [email protected]
de Bordeaux I, Gradignan, France; [email protected]
b) CENBG, CRNS-IN2P3-Université
References
1. J.N. Scheurer et al. Nucl. Instr. and Meth. A 385 (1997) 501.
2. J.Gál et al. Nucl. Instr. and Meth. A 516 (2004) 502.
The features of the DIAMANT array:
DIAMANT on service stand:
the flexi-board arrangement
Detectors: 84 pcs 3mm CsI(Tl) scintillators with
photodiode readout;
76 pcs square-shaped (14.5 mm)
8 pcs triangle-shape (29 mm)
special wrapping technique:
>80% light-collection efficiency;
-energy resolution: 2% (5.5 MeV)
Geometry Rhombicuboctahedron: flexible PCB
forward wall(s): 3x3 or 5x5 detectors
Efficiency
geometrical:
~ 90% of 4
detection of protons: > 70%
detection of alphas:  50%
High granularity
deduce particle multiplicity;
Doppler-correction of gammas
Electronics: in-vacuum preamplifiers;
VXI signal processing
The Octal Particle Discriminator
VXI Card
Output data from the VXI card
Example spectra of a CsI
detector
PID-vs-E
Energy (E)
Protons
Gating on individual (1D) or combined
(2D) spectra of these data enables the
- rejection of random events
- selection of reaction channels
- enhancement of gammas with
special conditions
Putting 1D gates on the
– Time: eliminates part of the random
coincidences
Alphas
–
PID
Time
PID:
improves channel selection
Putting 2D gates on
– PID-vs-Time: Further cleaning of
particle-gamma coincidences from
randoms; channel selection
–
PID-vs-E: Improved selection of
gammas in coincidence with protons
or alphas
Summary of EXOGAM experiments using DIAMANT at GANIL
Exp-#
E404S
E404aS
Spokesperson(s)
P.J.Nolan
+N.Redon
“
Date
Beam/Target
(MEV/mgcm-2)
Jun. 2002
76Kr/58Ni
Detectors
Status
EXG + DIAMANT
Resubmit
(320/1.1)
EXG + DIAMANT
Conf.,Thesis
+VAMOS
-----------------------------------------------------------------------------------------------------------------------------------------------Commission B.M.Nyakó
Oct. 2005
EXG+ DIAMANT
+J.N.Scheurer
+ n-Wall
E498S
E482
E451
S. Williams
A.Gadea
+S.Lenzi,
B. Cederwall
Oct. 2004 (328/1.1)
Oct. 2005
(60/1)
18
Ne/24Mg
EXG + DIAMANT
+ n-Wall
Nov. 2005
36
Nov. 2005
(111/6)
36Ar/58Ni
Ar/24Mg+Zr
(85/0.5+8)
EXG + DIAMANT
+ n-Wall
Not analysed
Oxigen (?)
Resubmitted
EXG + DIAMANT
Report by
+ n-Wall
K.Andgren
-----------------------------------------------------------------------------------------------------------------------------------------------E505
G.de Angelis
May 2006 36Ar/40Ca
EXG + DIAMANT
(No info)
+ n-Wall
E514
M. Palacz
+J.Nyberg
Jun. 2006
58Ni/54Fe
(240/8)
EXG + DIAMANT
+ n-Wall
In progress
trigger probl's
DIAMANT early implementations: exp.s E404S, E404aS
Physics motivation:
Identification of -rays in nuclei around the drip-line nucleus 130Sm: probing the maximally
deformed light rare-earth region
•
The 2+ energy of 130Sm, inferred to be 121 keV from fine structure in the ground-state
proton decay of 131Eu, predicts a large moment of inertia and hence large quadrupole
(prolate) deformation for this exotic nucleus
•
The nucleus 130Sm is thus an ideal candidate to assess the feasibility of gamma-ray
spectroscopy of exotic nuclei produced with radioactive ion beams of SPIRAL using
state-of-the-art detector systems
•
A pioneering experiment for EXOGAM using the DIAMANT ancillary detector;
Difficulty: low -ray energy to be identified - Need for special detector arrangment.
Experimental details
– Target: 1.1 mg/cm2 of 58Ni;
– Beam: Radioactive 76Kr ions (t1/2 = 14.8 h) of intensity ~5-8 x 105 particles per second
and energy ~4.5 MeV/u
• First Expt: ‘EXOGAM’ (6 segmented Clover detectors + 2 small Clover detectors)
+ DIAMANT (56 CsI detectors: 90°–ring + FW)
• Second Expt: ‘EXOGAM’ (11 segmented Clovers)
+ DIAMANT (48 CsI detectors) + VAMOS
From Nadine Redon
DIAMANT early implementations in EXOGAM
Early Implementation-1:
[5x5 forward wall + 90°-ring of 32 CsI];
beam
EXOGAM+DIAMANT setup with VAMOS:
Clovers @ 90° and backward angles
Early Implementation-2:
Sketch of the 'forward-only' version
(to minimize -absorption)
DIAMANT spectrum
Condition : at least 3p
Condition : at least 1
Nadine Redon: GANIL Oct. 2005
no condition
Physics motivations of the NWall + DIAMANT campaigns:
E498S High Spin States in the Tz=-3/2 Nucleus 37Ca – Mirror Symmetry at the
(S.W)
Largest Values of Isospin;
18Ne(60MeV) 1 mg/cm2 24Mg target;
DIAMANT: selective device
E482
(A.G)
Mirror Energy Differences in the A=58 T=1 mass triplet and Charge
Symmetry Breaking terms in the nuclear effective interaction above 56Ni;
36Ar(85MeV) 0.5 mg/cm2 24Mg target on 90Zr backing, 4pnA
Problem: Oxigen build-up in target;
DIAMANT: rejective device
E505
(GdA)
Electromagnetic decay properties of the Tz=±1/2 A=67 and 71 mirror pairs:
A test for isospin mixing and for pn pairing; DIAMANT: selective device
Neutron Single Particle Energies with Respect to 100Sn and Z=50 Core
Excitations by Investigating Excited States in 103Sn;
58Ni(240 MeV) 8 mg/cm2 54Fe target, 1.7 pnA
Problem: backing, trigger conditions;
DIAMANT: selective device
E514
(M.P)
E451
Search for T=0 pairing and a new coupling scheme in 92Pd and 88Ru
36Ar(111 MeV) 6 mg/cm2 58Ni target, 5 pnA
(B.C)
Problem: Efficiency; (To be reported next.) DIAMANT: selective device
DIAMANT „fuller” configuration for EXOGAM + NWall
experiments with stable and radioactive beams (Oct.-Dec. 2005, May-June 2006)
Radioactive beams: two quad detector modules had to be removed to allow the NBI target
loader pass through; This “fuller” configuration (Geom. Eff.: ~82 %) used for Stable beams
beam
Target Loader
DIAMANT mechanics in preparation
for the NWall + DIAMANT campaign.
Example spectra for DIAMANT performance
E482: ~ OK (~all worked)
E514: Problems with backward part
High beam intesity, targets sim.
PID-vs-E
for the same detector
Absorbent problem
Ta
Al
Comments on setup the VXI: check 2D spectra for correct operation!
Indicate improper
Discrimination mode
Mixed vs Ball. Def.
PID-vs-Time
Example spectra for DIAMANT performance (E482,E514)
Good charged particle selection
Good channel selection, but reduced
efficiency for DIAMANT (Marcin’s exp.)
p
2p
2α

1α1p
Energy
1α
1n
Good Time resolution (with loss in statist.)
Experimental observations during NWall campaigns
Performance of the CsI detectors:
thanks to Gábor Kalinka (labor), Giovanni La Rana (finance)
Excellent: with proper absorber (even with high-intensity beams)
Bad
if absorbers are not sufficient for killing scattered
ions/electrons
DIAMANT must be protected from direct beam --> beam profile monitoring
Performace of the electronics:
thanks to János Gál & József Molnár
Preamps: Excellent in spite of 'severe' conditions
VXI: very reliable with controlled temperature
One card is unstable - need testing
Overall Performance: good
Need for standard procedures to improve
reliability, ease of data analysis
Plans for improvements
Aim: Enhance the performance of DIAMANT by optimizing its features for
furture Ge-detector arrays intended for nuclear structure studies with high
intensity stable and radioactive beams of SPIRAL-2
Known Problems:
A.
Troublesome installation of CsI detectors in DIAMANT chamber
B.
CsI calibration, Target loading vs. efficiency, Vacuum feed-through
C. Maintenance of the DIAMANT VXI cards is not obvious
D. Limitations due to -absorption for E < 200 keV; CsI(Tl), PAs, cables
Future Improvements:
E.
Test the applicability of Avalange PD-s for CsI-s in DIAMANT
F.
The CsI electronics has to be compatible with next-generation
DAQ systems
G. Position sensitive detector setups?
Solving Problems – ad A.
Troublesome installation of CsI detectors:
Compact geometry – to fit DIAMANT chamber
inside EXOGAM configurations A and/or B
The (relatively) EASY bits:
The flexi board
equipped with
CsI + Ta-abs.;
Rigid but
versatile
geometry
and the DIFFICULT bits:
The flexi board
on support
stand, ready
for installation
Very tight arrangement
Solving Problems - ad B:
CsI calibration: Doppler correction, reaction mech. studies, etc.
with α-sources
In-beam,
Measured In-beam in ATOMKI
Problems:
In-beam - needs beam-time, cost
Sources: needs 232U or 228Th α-sources on target loader
γ-sources in target position (needs action from GANIL)
Solving Problems - ad B ctnd:
Particle-Energy calibration of CsI with -ray source
100
Particle Energy [MeV]
90
80
70
60
L (proton)
L (alpha)
50
40
30
20
10
0
0
10
20
30
40
50
60
70
80
90
Light-Yield L
Based on comparative α and γ calibrations:
Light yield vs E:
[D. Horn et al. NIM A420(1992)273]
100
Solving Problems - ad B (ctnd):
Target loading vs. efficiency.
Target loader for
radioactve beams
Alternative target holder for stable beams:
Enables the use of complete geometry
Need for beam collimation
New opening of the chamber - easy handling
New inside connectors and feed-throughs
(SA experience)
Vacuum feed-through for
glued ribbon cables
PCB feed-throughs for
DIAMANT on the
AFRODITE chamber
(iThema LABS, SA)
Solving Problems - ad C:
The VXI test-bench at GANIL
VXI cards for DIAMANT need low temp. (22C°)
Overheating happened in early exp.-s
Few VXI channels developed permanent
faults, some recovered
One card has problems, needs fixing:
Maintenance of the DIAMANT VXI cards:
Ageing: > 10-year old technology;
Obsolate parts/circuitries
(GIR experts left the field, etc.);
New VXI test-bench in GANIL -
now compatible with CsI-VXI cards
Personnal's help very much appreciated !
Need for dedicated slot(s) compatible
with DIAMANT VXI cards (Solved!)
Solving Problems – ad D:
Gamma-efficiency measured for
EUROBALL + DIAMANT installed
-absorption: caused mainly by CsI(Tl) + PAs, cables
DIAMANT:
Well suited for higher-energy -spectr.
In special configurations (cf. E404S)
absorption can be minimized
Aims: minimize material, make room for handling,
improve low-energy respons of the system
Solution:
Use of APD instead of pin-PD on CsI-s
Transition to Perspectives!
Hamamatsu S8664 ser.
short wavelength type
APD: 10x10mm2
Expected advantages of using avalange photodiodes:
1. Higher light collection efficiency, large gain, signal/noise,
--> improved particle discr. low-energy detection
2. Simpler PA arragement may be sufficient
--> easier handling
Plans for feasibility studies of using APD-s instead of pin-PD-s (EXOGAM-2 FP7 ?? G.d F.)
Future Improvements - ad E.
Properties of short wavelength type APD-s:
Hamamatsu S8664-10-10
good spectral response for CsI light
high quantum efficiency
low dark current at Vbd (Vopt~ 350V)
gain ~ 50 (T=20 C°)
Disadvantages:
Needs higher Voltage PS (opt. ~350 V)
Gain is temperature dependent --> stabilisation
APD with CsI(Tl):
Excellent resolution for X-rays, low-energy -s
[J.Kataoka et al. NIM A541(2005)398]
Coincidence spectroscopy with
PAD+CsI(Tl) can be done (?)
--> use of DIAMANT as gamma-array for L.E. -s
Ge-CsI coinc. time resolutions with DIAMANT
[J.Gál et al. NIM A516 (2004) 502]
Future Improvements - ad F:
Plans for Upgrading: Digital Signal Processing for the CsI electronics
for compatibility with next-generation gamma-arrays & DAQ systems
The ATOMKI solution: 4-channel DAQ module developed for miniPET
Block
of miniPET2
proposedDAQ
DAQmodule
module
Blockscheme
scheme of
Bicron LYSO
Fast
Fast
Prelude P420 24x24
3
preamp
preamp
1.9x1.9x12 mm
X+
Quad
XCsI
module
Fast
ADC
MEMEC miniModule with Gigabit Ethernet
LVDS
Base line restoration
C
PowerPC
Pulse recognition
Time stamp
Y+
Energy calculation
Y-
I
F
O
Hamamatsu
H9500 PMT
HV
PSPMT
CsI
Analog
Analog
frontend
frontend
Local clock
Analog
Devices
AD9229-65
Ethernet
10/100/1000
BaseT
F
H
W
M
A
C
To be developed at ATOMKI:
IP core - managing PID, Energy,etc.
from
digitalized
signals in the
FPGA
Xilinx V4 FX12
Xilinx Virtex-4 FPGA
MEMEC miniModule
P
H
Y
and/or
Optical
Module
Future Improvements:
position sensitive ΔE-E particle discrimination
In iThemba LABS DSSSD + CsI(Tl) arrays have been used (in collaboration with ATOMKI)
DSSSD
6Li(3He,t)6Be
3
He
at 50 MeV
4He
CsI(Tl)
The AFRODITE chamber equipped
with 60x60x0.3 mm3 Si DSSSD +
2x2 arrays of 30x30x3 mm3 CsI(Tl)
+ Si pin-PD (P.Papka's curtesy)
Example ΔE vs E spectrum produced by
the DSSSD + CsI(Tl) arrays on the left
Summary of Perspectives and Future Developments of
DIAMANT
Short-range plans:
Continue nuclear structure studies with EXOGAM using the stable and high-intensity
radioactive beams available at GANIL:
We propose DIAMANT for the nuclear spectroscopy community for studying nuclei
for E > 200 keV. We plan to use it also with AFRODITE (TLABS, SA) and even to
test it with the demonstrator version of the future AGATA array.
With the technical developments outlined, there is hope for a succesful continuation!
Long(er)-range plans:
Develop a prototype CsI+APD detector and dedicated Preamplifier: (Plan)
Test its applicability for low-energy coincidence spectroscopy
Use Digital Signal Processing to replace the present VXI electronics (Needs financing!)
for compatibility with EXOGAM-2 and AGATA
Options:
Use the 4-channel module under development in ATOMKI (Plan within EXOGAM-2)
Dedicated Xilinx programs to be developed for CsI detector signals at ATOMKI;
Use the circuitry under development for the Ge detectors of AGATA/GRETA
[I.H. Lazarus et al, The GRT4 Pulse Processing Card ...., 2003]
Need help from physics groups to realize the planned
Future Developments of DIAMANT
List of volunteers:
Form of contribution:
To be completed!
Thanks
Members of the DIAMANT Collaboration:
J.N. Scheurer et al1, G. La Rana et al2,
J. Gál3, G. Hegyesi3, G. Kalinka3, J. Molnár3, B.M. Nyakó3, K. Juhász4
A. Algora3, Zs. Dombrádi3, J. Timár3, L. Zolnai3
1CENBG,
CRNS-IN2P3-Université de Bordeaux I, Gradignan Cedex, France
2Dipartimento di Fisica, Universita di Napoli and INFN, Napoli, Italy
3Institute of Nuclear Research, (ATOMKI), Debrecen, Hungary
4Faculty of Informatics, University of Debrecen, Debrecen, Hungary
&
To all colleagues
of the many physics groups from different EU and outside laboratories
who provided material about the status of data analysis and
results of experiments