NEDA NEutron Detector Array A possible neutron detector

NEDA (NEutron Detector Array): A possible neutron detector for LUNA-MV 22 Ne(α, n)25 Mg & 13 C(α, n)16 O J. J. Valiente Dobón (LNL-INFN) on behalf of the NEDA collaboration

Overview • • • The origins of the NEDA detector Organization of the NEDA collaboration - Mo. U Conceptual design On going work on NEDA Some thoghts of NEDA @ LUNA-MV Summary

Neutron Wall

In beam spectroscopy of 92 Pd N = Z 92 Pd Nature vol. 469 (2011) Use of fusion evaporation reactions to populate very neutron-deficient nuclei – (gamma-ray deetctors, charged particles and neutron detctors) 36 Ar+58 Ni 92 Pd +2 n

Physics with NEDA will address the physics of neutron-rich as well as neutron-deficient nuclei, mainly in conjunction with gamma-ray detector arrays like GALILEO, AGATA, EXOGAM 2 and PARIS. • • • Nuclear Structure – Probe of the T=0 correlations in N=Z nuclei: the structure beyond 92 Pd (Uppsala, LNL, Padova, GANIL, Stockholm, York) – Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states (Warsaw, LNL, Padova, GANIL, York) – Coulomb Energy Differences and Nuclear Shapes (York, Padova, GANIL) – Low-lying collective modes in proton rich nuclei (Valencia, Krakow, Istanbul, Milano, LNL, Padova) Nuclear Astrophysics – Element abundances in the Inhomogeneous Big Bang Model) 8 Li(α, n)11 B (Weizmann, Soreq, LNS, Sez. Catania, GANIL) – Isospin effects on the symmetry energy and stellar collapse (Naples, Debrecen, LNL, LNS, Sez. Catania, Florence) Nuclear Reactions – Level densities of neutron-rich nuclei (Naples, LNL, LNS, Sez. Catania, Florence) – Fission dynamics of neutron-rich intermediate fissility systems (Naples, Debrecen, LNL, LNS, Sez. Catania, GANIL)

Organization of NEDA Spokesperson: J. J. Valiente Dobon (LNL-INFN) GANIL Liason: M. Tripon (GANIL) Management board: FP 7 -INFRASTRUCTURES-2007 -1 -B. Wadsworth (U. of York) SPIRAL 2 PREPARATORY PHASE -N. Erduram (Istanbul Sabahattin Zaim U. ) -G. De France (GANIL) FIRB (2008) FUTURO IN RICERCA (MIUR) -J. Nyberg (U. of Uppsala) Istituto Nazionale Fisica Nucleare -M. Palacz (U. of Warsaw) (Gruppo III) -A. Gadea (IFIC - Valencia) -D. Tonev (INRNE – Bulgaria) Within Nu. PNET (2011) NEDENSAA project Mo. U (4 years) signed in march 2012 by Bulgaria, France, Turkey, Poland, Sweden, United Kingdom. To be signed by: Italy and Spain

Parties of the collaboration Parties • Bulgaria: Institute for Nuclear Research and Nuclear Energy (INRNE) • France: GANIL • Italy: Istituto Nazionale di Fisica Nucleare (INFN) • Poland: Consortium of Polish Governmental and Public Institutions (COPIN) • Spain: Conselleria d'Educació, Generalitat Valenciana/Secretaría de Estado de Investigación, Desarrollo e Innovación/Ministerio de Economía y Competitividad/Centro Superior de Investigaciones Cientificas (CSIC)/ Universidad de Valencia/Istituto de Física Corpuscular (IFIC) • Sweden: Uppsala University • Turkey: The Scientific and Technological Research Council of Turkey (TUBITAK)/ Turkish Atomic Energy Authority (TAEK) • United Kingdom: York University

Aim and strategy of NEDA Aim • Develop a neutron detector array to be used with gamma-ray arrays such as AGATA, GALILEO, EXOGAM 2, PARIS, etc. , for experiments with high intensity stable and radioactive ions beams The array should have: • Increased neutron detection efficiency compared to Neutron Wall: ε(1 n) ≈ 40% (2025%), ε(2 n) ≈ 6% (1 -2%). • Excellent neutron-gamma discrimination. • Capability to run at much higher count rates than with the Neutron Wall. • Cope with large neutron multiplicities in reactions with neutron-rich RIBs. • Improved neutron energy resolution for reaction studies. Strategy • Optimise size of detector units, distance to target, geometry of the array, . . . • Investigate other detector materials than ordinary liquid scintillator. • Adopt digital electronics which are fully compatible with AGATA, GALILEO, EXOGAM 2, PARIS. . . • Develop advanced on-line and off-line algorithms for neutron-gamma discrimination, neutron scattering rejection.

NEDA conceptual design

Simulations: Single cell unit Detailed study of GEANT 4 simulations for a single detector of NEDA. G. Jaworski et al. , NIM A 673 (2012) 64 -72

Conceptual design of NEDA Staircase-2π geometry • Individual cells: 355 • Three liter of BC 501 A or the equivalent ELJEN EJ 309 (high flashpoint 144 o not considered dangerous good material) • One meter To. F • Self procution of the detectors • Photomultiplier: Hamamatsu R 4144 or high quantum efficiency SB

Design of the NEDA cells Self production PM Expansion chamber BC 501 A EJ 309 The prototype has been designed to be as much compact and economic as possible. The hexagonal cell is ~3 L volume with a sideto-side distance of 146 mm designed in Al alloy 2011 (inner distance is 133 mm), 20 cm tall. The case fits 1 mm mu-metal shield.

prompt trigger Digitizer Pre-processing GTS local REQ VAL PSA Event Builder Global Merger Tracking Online analysis Digitizer GTS local Pre-processing PSA GTS supervisor Event Builder 200 MHz 14 bit NEDA GAMMA-ARRAY NEDA coupled to GALILEO/AGATA/EXOGAM 2/PARIS

Tests of the FADC for NEDA/EXOGAM 2 A test bench has been designed The FADC uses the ADS 62 P 49 flash ADC: 200 MHz and 14 bit snapshot of the system working with a real detector. Measurements, such as timing and gamma-neutron discrimination have been performed at LNL in december 2012 using a Cf source.

NEDA test setup The tests are being performed at LNL with the following instrumentation: • • • 2 x BC 501 A (5” x 5” cylindrical prototype detector) 2 x BC 537 (5” x 5” cylindrical prototype detector) SIS 3302 100 MS/s, 16 bits 8 ch. digitizer (analog setup) SIS 3350 500 MS/s, 12 bits 4 ch. digitizer DAQ by IFIC, J. Agramunt • Digital PSA • Relative efficiency performance • Cross-talk between the detectors BC 501 A BC 537 15 Ba. F 2

Tests: Preliminary timing 500– 200 MHz We are currently working on two different algorithms for digital timing: • CFD (Constant Fraction Method) method with a cubic interpolation of the ZCO (Zero Cross Over) • Cubic interpolation at 50% Amplitude • fit of the rising time with a Fermi-like function. Fermi CFD FWHM = 1. 23 ns for CFD at 500 MHz. FWHM = 2. 03 ns for CFD at 200 MHz. FWHM = 1. 32 ns at 500 MHz. FWHM = to be done at 200 MHz The time resolution is obtained for the Super. Bialkalyne PMT with a 60 Co source and for two frequencies 500 MHz (the nominal) and 200 MHz (final NEDA one)

Tests: PSA Neural Network Pulse shape discrimination for NEDA Traditional NN Full advantage of digital electronics can be obtained using artificial neural networks to perform pulse-shape discrimination. This method is currently being investigated both for BC 537 and BC 501 A. + Optimal discrimination over a large energy range - Slower implementation limits counting rate P. A. Soderstrom et al. , to be submitted NIM A

New materials for neutron detection

Tests of new material at LNL EJ 299 The new scintillator EJ 299 3’’x 3’’ is being tested at LNL. It was provided by SCIONIX with a ETL PMT already mounted. 22 Na Preliminary results are obtained that for the moment are kept confidential

Some thoughts about NEDA@LUNA-MV • • • Reactions of interest: – 13 C(α, n)16 O (2 Me. V <E < 3 Me. V) n – 22 Ne(α, n)25 Mg(0. 1 Me. V <E < 0. 45 Me. V) n Parameters of interest: neutron counting rate, energy En, possibly En(θ). What does NEDA offer? Flexible geometry No sensitivity to thermal neutrons Good PSA capabilities Digital electronics NN PSA Possibility to measure angular distributions Good timing at 200 MHz sampling better than 2 ns Possibility to measure En (ΔΕ/Ε~10%), needed TOF (pulsed beam or some other time reference)

Some thoughts about NEDA@LUNA-MV • • Drawbacks: Sensitive to gamma rays BC 501 A dangerous material – Much less dangerous EJ 309 Thresholds 22 Ne(α, n)25 Mg(0. 1 Me. V <En< 0. 45 Me. V): – 100 ke. V – 7. 4 ke. Vee – 300 ke. V – 27 Ke. Vee E. Dekempeneer et al. , (1987). NIM 256(3), 489– 498 – 500 ke. V – 57 Ke. Vee

Summary • • NEDA will be a neutron detector to address the physics of neutron-rich as well as neutron-deficient nuclei, mainly in conjunction with gamma-ray detector arrays like AGATA, GALILEO, EXOGAM 2 and PARIS. The collaboration has a clear interest on the LUNA-MV physics • • Exhaustive simulations (G. Jaworski et al. NIM 673 (2012) 64 -72) Design of the first NEDA prototype, currently being constructed Development of electronics in synergy with EXOGAM 2 and PARIS Continuous tests at LNL on: – Relative efficiency – Timing – PSA – new materials EJ 299 -33 • • • NEDA will be built in phases: Mo. U signed March 2012. NEDA will be coupled to the NW+AGATA at the AGATA GANIL phase Strong synergies with other neutron communities: MONSTER, DESIR, NEULAND