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NEDA (NEutron Detector Array)

NEDA (NEutron Detector Array). J.J. Valiente Dobon (LNL-INFN) on behalf of the NEDA collaboration. Organization. Spokeperson: J.J. Valiente Dobon (LNL-INFN) GANIL Liason: M. Tripon (GANIL) Steering committee: -B. Wadsworth (U. of York) -N. Erduram (U. of Istanbul)

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NEDA (NEutron Detector Array)

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  1. NEDA (NEutron Detector Array) J.J. Valiente Dobon (LNL-INFN) on behalf of the NEDA collaboration

  2. Organization Spokeperson: J.J. Valiente Dobon (LNL-INFN) GANIL Liason: M. Tripon (GANIL) Steering committee: -B. Wadsworth (U. of York) -N. Erduram (U. of Istanbul) -L. Sttugge (IRES – Strasbodurg) -J. Nyberg (U. of Uppsala) -M. Palacz (U. of Warsaw) -A. Gadea (IFIC - Valencia) Members of the collaboration: U. of Ankara (Turkey), COPIN (Poland), CSIC-IFIC (Spain), Daresbury Laboratory (U.K.), GANIL (France), U. of Istanbul (Turkey), INFN (Italy), IRES (France), U. of Nidge (Turkey), U. of Uppsala (Sweeden), U. of York (U.K.) and Kolkata, India (under discussion) FP7-INFRASTRUCTURES-2007-1 SPIRAL2 PREPARATORY PHASE

  3. Working groups • Detector characteristics (Physics interests of NEDA to define the detector specifications). • Responsible: B. Wadsworth • Geometry (Make a full study of geometry to determine (materials) efficiency, reduce cross-talk, ... Comparison between different codes: Geant4, MCNP-X. Simulate effect of other ancillaries, neutron scattering.). • Responsible: M. Palacz • Study New Materials (Exploring new materials, solid scintillators, deuterated liquid scintillators). • Responsible: L. Stuttgé • Digital Electronics (Flash ADCs, GTS, EXOGAM2 electronics, ..) • Responsible: A. Gadea • PSA (Pulse shapes analysis, PSA algorithms, ...). • Responsible: J. Nyberg • Synergies other detectors (Detectors that can be considered in synergy with NEDA: EXOGAM2, PARIS, AGATA, FAZIA, GASPARD, DIAMANT, DESCANT, Neutron spectroscopy at DESIR, DESPEC/HISPEC, NEUTROMANIA, ... ). • Responsible: P. Bednarczyk

  4. Physics with NEDA NEDA will address the physics of neutron-rich as well as neutron deficient nuclei, mainly in conjunction with gamma-ray detectors arrays like AGATA, EXOGAM2, GALILEO and PARIS. • Nuclear Structure • Probe of the T=0 correlations in N=Z nuclei: The structure beyond 92Pd (Uppsala, LNL, GANIL, Stockholm, York) • Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states (Warsaw, LNL, GANIL, York) • Coulomb Energy Differences and Nuclear Shapes (York, Padova, GANIL) • Low-lying collective modes in proton rich nuclei (Valencia, Istanbul, Milano, LNL, Krakow) • Nuclear Astrophysics • Element abundances in the Inhomogeneous Big Bang Model (Weizmann, Soreq, GANIL) • Isospin effects on the symmetry energy and stellar collapse (Naples, Debrecen, LNL, Florence) • Nuclear Reactions • Level densities of neutron-rich nuclei (Naples, LNL, Florence) • Fission dynamics of neutron-rich intermediate fissility systems (Naples, Debrecen, LNL, GANIL) AGATA: A. Gadea EXOGAM2: G. de France GALILEO: C. Ur PARIS: D. Jenkins

  5. First day experiment AGATA/EXOGAM2 + NEDA Nuclear structure N=Z beyond 92Pd : 96Cd, etc

  6. Second day experiment PARIS + NEDA Low-lying collective modes in proton rich nuclei N=20 Transition densities

  7. NEDA+PARIS experiment Courtesy M. Lewitowicz The reaction to study the Pigmy resonance in 44Cr 34Ar + 16O → 44Cr + 2n(34Ar 108 pps)

  8. Physics themes • G de Angelis – Physics with NEDA • G. de France - Results on the 92Pd experiment • A. Gottardo - Study of proton-rich nuclei with NEDA around A=100 • A. Pipidis - NEDA: At the service of n-p correlations • M. Palacz - Spectroscopy next to 100Sn: 3n gating and where is 100In? • A. Di Nitto – The role of isospin in fusion-evaporation reactions • G. Verde - The Farcos project and access to the symmetry energy with proton-neutron measurements

  9. Problem definition • -NEDA: Neutron detector to be used coupled to AGATA/EXOGAM2/GALILEO/PARIS • -Previous experience with the NWall (BC501) currently at GANIL • -High efficiency 25% for one neutron. • -Relatively good gamma/neutron discrimination. • -Problems with cross talk. • -Low efficiency for 2n (1-2%). • -Analogic electronics.

  10. Neutron Wall

  11. Neutron Wall

  12. Neutron Wall: N=Z-2 28Si(28Si,2nα)50Fe 24Mg(32S,2n)54Ni S. Lenzi et al., PRL87, 122501 (2001) A. Gadea et al., PRL97, 152501 (2006)

  13. Cross talk – low 2n cross section • High cross talk between neighboring detectors • It is not possible to differenciate between 2n real events or just 1n scattered. • Therefore neighbouring detectors are dismiss in the analysis and the efficiency decreases to 1-2%. J. Ljungvall et al., NIMA528 471 (2004) Possible to improve 2n efficiency using TOF among detectors One aim of NEDA is to be able to distinguish between real 2n events and scattered neutrons → Increase of the 2n efficiency.

  14. Strategy of NEDA • -Optimization of the geometry: unitary cell size, spherical, planar, zig-zag, granularity, distance, versatile. • -FEE: GTS integrated in the motherboard and FADC in a mezzanine. Fully compatible with AGATA, GALILEO and EXOGAM2 • -Use of the TOF information in addition to the measured energy to disentangle the 1n scattered events from the real 2n channels • -Use of the deuterated scintillator BC537 • Pulse height seems to be proportional to incident neutron energy (reported by DESCANT collaboration) • Provides another method of determinig neutron energy beyond TOF • -Can lead to a better discrimination of high multiplicity neutron events and scattered events. • -New solid scintillators  Lawrence Livermore National Laboratory

  15. BC501 vs. BC537 response Presented by P. Garrett BC501 BC537 DESCANT En = 2.5 MeV En = 4.3 MeV BC501A BC537 Courtesy of P. Garrett, University of Guelph.

  16. Solid scintillators for neutron detection

  17. Simulations Presented by M. Palacz • Neutron HP model in G4.9.2.p01 (rel. March 2009) much improved comparing to earlier versions • Total cross sections and angular distributions for elastic scattering on p, d, and 12C reasonable • Correct (high energy) γ-ray lines produced • Wrong kinematics (angular distributions?) in the 12C(n,α)9Be reaction. • Important reactions still missing, like 12C(n,n’)3α Existing defficiencies not significant in the <~10MeV energy range, which if interest for NEDA

  18. Light output of liquid scintillator • The light-output L is usually given in MeVee: the particle energy required to generate 1 MeVee of light is defined as 1 MeV for fast electrons • L is generally less for heavier particles such as protons, deuterons, alphas, beryllium, carbon… • Therefore, the light output L in a certain path dx is a function of the deposited energy E in dx: L(E) Deposited energy Light output Presented by A. Gottardo Dekempeneer et Liskien NIM A 256 (1987) 489-498

  19. Geometry study Presented by G. Jaworski Definition of the unitary cell dimensions

  20. Geometries • There are two possible main geometries, either spherical or planar. • The spherical geometry presents the full symmetry. • The planar has some advantages, than the spherical does not present. • -Flexibility – different arrangements of the detectors, e.g. zig-zag • -Different focal posistions (500cm, 1000cm, 2000cm) • -Budget issues

  21. Performance of diff. geometries Flat Zig-zag Spherical BC501A BC537 Presented by T. Hüyük

  22. Discriminating neutron/gamma • Pulse shapes from the detector differs between neutrons and gamma rays. neutrons • Usually both pulse shape analysis and the time-of-flight information is used for discrimination neutron-gamma discrimination.

  23. Digital electronics: PSA It is possible to obtain better quality using same algorithms but digital electronics Analog zero-crossover method

  24. Digital electronics: Neural Network • Applying an artificial neural network can increase the quality even further P=sqrt(εn2+εγ2)

  25. NEDA coupled to AGATA/EXOGAM2 prompt trigger Digitizer Digitizer REQ VAL REQ VAL Pre-processing GTS local Pre-processing GTS local NEDA GAMMA-ARRAY PSA PSA GTS supervisor Event Builder Event Builder Global Merger Tracking Online analysis

  26. Digital electronics: EXOGAM2-NEDA MGT Clocks Fast serial links Parallel links Slow control Serial link Presented by M. Tripon Basic diference EXOGAM2/NEDA is the ADC: 200-300 MHz 12-14bit

  27. Silicon Photo multipliers readout SPMPlus • Direct replacement for photomultiplier tube • Insensitive to magnetic fields • Can operate in vacuum • Large sizes possible • Attractive for simultaneous PET and MRI scanning Synergy with PARIS – D. Jenkins

  28. BC501A and BC537 detectors Currently bought commercial detectors from Saint Gobain • Two detectors 5”x5” BC537 (LNL-INFN) • Two detectors 5”x5” BC501A (York-Valencia) A. Pipidis (founded SP2PP) working on the characterization of the detectors.

  29. Summary • Currently bought BC537 and BC501A commercial detectors to test: • cross talk • light production • FADC – frecuency and number of bits – PSA – neutron-gamma discrimination • First contacts with Livermore – Start up collaboration solid scintillators? • Test of SPMPlus from York in BC537 and BC501A • Development of electronics in synergy with EXOGAM2 • Optimal geometry

  30. Workshop program

  31. Phases of NEDA The current development on new materials and readout systems for neutron detection makes necessary to build NEDA in four different phases: • Phase 0: Upgrade of Neutron Wall with digital electronics. • Phase 1: R&D on new material and light readout systems for a highly segmented neutron detector array. • Phase 3: Construction of a limited size Demonstrator  • Phase 4: Final construction of NEDA

  32. With current technological status … • Three main options: • 200 detectors BC501A – PM readout –Digital electronics • Total cost: 600K€ (BC501A) + 200K€(Elec.) + 40K€ (mechanics) = 840 K€ • 200 detectors BC536 – PM readout – Digital electronics • Total cost: 2000K€ (BC537) + 200K€(Elec.) + 40K€ (mechanics) = 2240 K€ • Upgrade Neutron Wall - Phase 0 (Digital electronics) • Total cost (50 channels) = 40K€

  33. Collaborating Institutes • Centro Superior de Investigaciones Cientificas (CSIC) – Valencia • Grand Accelerateur National d’Ions Lourds (GANIL) • Istituto Nazionale di Fisica Nucleare – Laboratori Nazionale di Legnaro • Royal Institute of Technology - KTH • University of Istanbul • University of Lund • University of Nidge • University of Uppsala • University of Warsaw • University of York

  34. Summary and future work • NEDA – Looks at improving efficiency for 2n channels – BC537, geometry • Validated simulatons – realistic results for BC501 and BC537 • Included model for light production. • PSA algorithms to discriminate neutron-gamma – Neural Network great perspectives. • Synergies • PARIS (A. Maj): SPMPlus, electronics? • EXOGAM (G. De France): electronics • Neutron Spectroscopy at DESIR (D. Cano & N. Orr): Simulations, FADC FUTURE WORK • Currently bought BC537 and BC501 commercial detectors to test: • cross talk • light production – PSA – neutron-gamma discrimination • Test of SPMPlus from York in BC537 and BC501 • Development of electronics in synergy with EXOGAM2 • Design of FADC mezzanines • Optimal geometry

  35. NEDA possible geometries Spherical Step-spherical

  36. Neutron-γ discrimination BC537 n-γ discrimination BC501A(D) n-γ discrimination

  37. Light output

  38. Time scale

  39. Silicon PM

  40. Synergies PARIS EXOGAM array

  41. Commercial electronics: Struck 4 channel VME digitizer/transient recorder with a sampling rate of up to 500 MS/s (for the individual channel) and 12-bit resolution Programmable FPGAs

  42. Intrinsic efficiency of BC501A and BC537

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