Presentation on theme: "The DIAMANT light-charged particle detector: Performance and plans for improvements The DIAMANT light-charged particle detector: Performance and plans."— Presentation transcript:
The DIAMANT light-charged particle detector: Performance and plans for improvements 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 HIL, Warsaw
DIAMANT is a high-granularity, 4π light charged-particle detector array  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 . Contact persons: B.M. Nyakó a, J.N. Scheurer b a) Institute of Nuclear Research, (ATOMKI), Debrecen, Hungary; b) CENBG, CRNS-IN2P3-Université de Bordeaux I, Gradignan, France; References 1. J.N. Scheurer et al. Nucl. Instr. and Meth. A 385 (1997) J.Gál et al. Nucl. Instr. and Meth. A 516 (2004) The DIAMANT collaboration 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.
The Octal Particle Discriminator VXI Card DIAMANT on service stand: the flexi-board arrangement The features of the DIAMANT array: 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) GeometryRhombicuboctahedron: flexible PCB forward wall(s): 3x3 or 5x5 detectors Efficiencygeometrical: ~ 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
Output data from the VXI card 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 – 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 PID-vs-E PID Energy (E) Time Alphas Protons Example spectra of a CsI detector
DIAMANT early implementations: exp.s E404S, E404aS The 2 + energy of 130 Sm, inferred to be 121 keV from fine structure in the ground-state proton decay of 131 Eu, predicts a large moment of inertia and hence large quadrupole (prolate) deformation for this exotic nucleus The nucleus 130 Sm 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. Physics motivation: Identification of -rays in nuclei around the drip-line nucleus 130 Sm: probing the maximally deformed light rare-earth region –Target: 1.1 mg/cm 2 of 58 Ni; –Beam: Radioactive 76 Kr ions (t 1/2 = 14.8 h) of intensity ~5-8 x 10 5 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) From Nadine Redon Second Expt: ‘EXOGAM’ (11 segmented Clovers) + DIAMANT (48 CsI detectors) + VAMOSFrom Nadine Redon Experimental details
DIAMANT early implementations in EXOGAM Early Implementation-1: [5x5 forward wall + 90°-ring of 32 CsI]; EXOGAM+DIAMANT setup with VAMOS: 90° and backward angles beam Early Implementation-2: Sketch of the 'forward-only' version (to minimize -absorption)
Nadine Redon: GANIL Oct DIAMANT spectrum no condition Condition : at least 3p Condition : at least 1
Physics motivations of the NWall + DIAMANT campaigns: E498SHigh Spin States in the Tz=-3/2 Nucleus 37 Ca – Mirror Symmetry at the (S.W)Largest Values of Isospin; 18 Ne(60MeV) 1 mg/cm2 24 Mg target;DIAMANT: selective device E482Mirror Energy Differences in the A=58 T=1 mass triplet and Charge (A.G)Symmetry Breaking terms in the nuclear effective interaction above 56 Ni; 36 Ar(85MeV) 0.5 mg/cm2 24 Mg target on 90Zr backing, 4pnA Problem: Oxigen build-up in target;DIAMANT: rejective device E505Electromagnetic decay properties of the Tz=±1/2 A=67 and 71 mirror pairs: (GdA)A test for isospin mixing and for pn pairing;DIAMANT: selective device E514Neutron Single Particle Energies with Respect to 100 Sn and Z=50 Core (M.P)Excitations by Investigating Excited States in 103 Sn; 58 Ni(240 MeV) 8 mg/cm2 54 Fe target, 1.7 pnA Problem: backing, trigger conditions;DIAMANT: selective device E451Search for T=0 pairing and a new coupling scheme in 92 Pd and 88 Ru (B.C) 36 Ar(111 MeV) 6 mg/cm2 58 Ni target, 5 pnA Problem: Efficiency; (To be reported next.)DIAMANT: selective device
DIAMANT „fuller” configuration for EXOGAM + NWall 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 DIAMANT mechanics in preparation for the NWall + DIAMANT campaign. beam Target Loader
High beam intesity, targets sim. PID-vs-E for the same detector Absorbent problem TaAl Example spectra for DIAMANT performance Example spectra for DIAMANT performance E482: E514: E482: ~ OK (~all worked)E514: Problems with backward part High beam intesity, targets sim. PID-vs-E for the same detector Absorbent problem TaAl Comments on setup the VXI: check 2D spectra for correct operation! PID-vs-Time Indicate improper Discrimination mode Mixed vs Ball. Def.
Example spectra for DIAMANT performance (E482,E514) Example spectra for DIAMANT performance (E482,E514) 1n 1α1α 1 α 1p 2 α Good channel selection, but reduced efficiency for DIAMANT (Marcin’s exp.) Good Time resolution (with loss in statist.) Energy p 2p Good charged particle selection
Experimental observations during NWall campaigns Performace of the electronics: 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 Performance of the CsI detectors: thanks to Gábor Kalinka (labor), Giovanni La Rana (finance) Excellent:with proper absorber (even with high-intensity beams) Badif absorbers are not sufficient for killing scattered ions/electrons DIAMANT must be protected from direct beam --> beam profile monitoring Overall Performance: good Overall Performance: good Need for standard procedures to improve reliability, ease of data analysis
Plans for improvements 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? 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
Solving Problems – ad A. Troublesome installation of CsI detectors: Compact geometry – to fit DIAMANT chamber inside EXOGAM configurations A and/or B The flexi board equipped with CsI + Ta-abs.; Rigid but versatile geometry The flexi board on support stand, ready for installation The (relatively) EASY bits: and the DIFFICULT bits: Very tight arrangement
Solving Problems - ad B: CsI calibration: Doppler correction, reaction mech. studies, etc. In-beam,with α-sources Measured In-beam in ATOMKI Problems: Problems: In-beam - needs beam-time, cost Sources: needs 232 U or 228 Th α-sources on target loader γ-sources in target position (needs action from GANIL)
Solving Problems - ad B ctnd: Based on comparative α and γ calibrations: Based on comparative α and γ calibrations: [D. Horn et al. NIM A420(1992)273] Light yield vs E:
Solving Problems - ad B (ctnd): Target loading vs. efficiency. Target loader for radioactve beams Vacuum feed-through for glued ribbon cables PCB feed-throughs for DIAMANT on the AFRODITE chamber (iThema LABS, SA) 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)
Solving Problems - ad C: 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!) The VXI test-bench at GANIL
Solving Problems – ad D: -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 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 Gamma-efficiency measured for EUROBALL + DIAMANT installed Hamamatsu S8664 ser. short wavelength type APD: 10x10mm 2 Plans for feasibility studies of using APD-s instead of pin-PD-s (EXOGAM-2 FP7 ?? G.d F.) Transition to Perspectives!
Future Improvements - ad E. Properties of short wavelength type APD-s: good spectral response for CsI light high quantum efficiency low dark current at V bd (V opt ~ 350V) gain ~ 50 (T=20 C ° ) Disadvantages: Needs higher Voltage PS (opt. ~350 V) Gain is temperature dependent --> stabilisation Hamamatsu S APD with CsI(Tl): Excellent resolution for X-rays, low-energy -s [J.Kataoka et al. NIM A541(2005)398] --> use of DIAMANT as gamma-array for L.E. -s Coincidence spectroscopy with PAD+CsI(Tl) can be done (?) Ge-CsI coinc. time resolutions with DIAMANT [J.Gál et al. NIM A516 (2004) 502]
Analog Devices AD PSPMT Analog frontend MEMEC miniModule Block scheme of miniPET2 DAQ module HV FPGA Xilinx V4 FX12 C PowerPC Fast ADC Fast preamp Ethernet 10/100/1000 BaseT X+ X- Y- Y+ FIFOFIFO Base line restoration Pulse recognition Time stamp Energy calculation Local clock HWMACHWMAC Hamamatsu H9500 PMT Bicron LYSO Prelude P420 24x24 1.9x1.9x12 mm 3 LVDS PHYPHY CsI Analog frontend Fast preamp Quad CsI module 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 scheme of proposed DAQ module and/or Optical Module To be developed at ATOMKI: IP core - managing PID, Energy,etc. from digitalized signals in the Xilinx Virtex-4 FPGA MEMEC miniModule with Gigabit Ethernet
Future Improvements: position sensitive ΔE-E particle discrimination In iThemba LABS DSSSD + CsI(Tl) arrays have been used (in collaboration with ATOMKI) CsI(Tl) DSSSD The AFRODITE chamber equipped with 60x60x0.3 mm 3 Si DSSSD + 2x2 arrays of 30x30x3 mm 3 CsI(Tl) + Si pin-PD (P.Papka's curtesy) Example ΔE vs E spectrum produced by the DSSSD + CsI(Tl) arrays on the left 3 He 4 He 6 Li( 3 He,t) 6 Be at 50 MeV
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 al 1, G. La Rana et al 2, J. Gál 3, G. Hegyesi 3, G. Kalinka 3, J. Molnár 3, B.M. Nyakó 3, K. Juhász 4 A. Algora 3, Zs. Dombrádi 3, J. Timár 3, L. Zolnai 3 1 CENBG, CRNS-IN2P3-Université de Bordeaux I, Gradignan Cedex, France 2 Dipartimento di Fisica, Universita di Napoli and INFN, Napoli, Italy 3 Institute of Nuclear Research, (ATOMKI), Debrecen, Hungary 4 Faculty 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