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 - MoU Conceptual design On going work on NEDA Some thoghts of LUNA-MV Summary

Neutron Wall

N = Z 92 Pd In beam spectroscopy of 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 +2n 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 +2n

Physics with NEDA 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) 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, EXOGAM2 and PARIS.

Organization of NEDA Spokesperson: J.J. Valiente Dobon (LNL-INFN) GANIL Liason: M. Tripon (GANIL) Management board: -B. Wadsworth (U. of York) -N. Erduram (Istanbul Sabahattin Zaim U.) -G. De France (GANIL) -J. Nyberg (U. of Uppsala) -M. Palacz (U. of Warsaw) -A. Gadea (IFIC - Valencia) -D. Tonev (INRNE – Bulgaria) FP7-INFRASTRUCTURES SPIRAL2 PREPARATORY PHASE FP7-INFRASTRUCTURES SPIRAL2 PREPARATORY PHASE FIRB (2008) FUTURO IN RICERCA (MIUR) FIRB (2008) FUTURO IN RICERCA (MIUR) MoU (4 years) signed in march 2012 by Bulgaria, France, Turkey, Poland, Sweden, United Kingdom. To be signed by: Italy and Spain Within NuPNET (2011) NEDENSAA project Within NuPNET (2011) NEDENSAA project Istituto Nazionale Fisica Nucleare (Gruppo III) Istituto Nazionale Fisica Nucleare (Gruppo III)

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, EXOGAM2, 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(1n) ≈ 40% (20- 25%), ε(2n) ≈ 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, EXOGAM2, PARIS... Develop advanced on-line and off-line algorithms for neutron-gamma discrimination, neutron scattering rejection.

NEDA conceptual design

Simulations: Single cell unit G. Jaworski et al., NIM A 673 (2012) Detailed study of GEANT4 simulations for a single detector of NEDA.

Staircase-2π geometry Individual cells: 355 Three liter of BC501A or the equivalent ELJEN EJ309 (high flashpoint 144 o not considered dangerous good material) One meter ToF Self procution of the detectors Photomultiplier: Hamamatsu R4144 or high quantum efficiency SB Conceptual design of NEDA

Design of the NEDA cells Self production The prototype has been designed to be as much compact and economic as possible. The hexagonal cell is ~3L volume with a side- to-side distance of 146 mm designed in Al alloy 2011 (inner distance is 133 mm), 20 cm tall. The case fits 1mm mu-metal shield. PM Expansion chamber BC501A EJ309 BC501A EJ309

GTS supervisor Event Builder PSA Pre-processing Digitizer Tracking Online analysis GTS local prompt trigger REQ VAL REQ VAL Global Merger GAMMA-ARRAY GTS local Event Builder PSA Pre-processing Digitizer NEDA NEDA coupled to GALILEO/AGATA/EXOGAM2/PARIS 200MHz 14bit 200MHz 14bit

Tests of the FADC for NEDA/EXOGAM2 Measurements, such as timing and gamma-neutron discrimination have been performed at LNL in december 2012 using a Cf source. A test bench has been designed snapshot of the system working with a real detector. The FADC uses the ADS62P49 flash ADC: 200MHz and 14bit

15 The tests are being performed at LNL with the following instrumentation: 2 x BC501A (5” x 5” cylindrical prototype detector) 2 x BC537 (5” x 5” cylindrical prototype detector) SIS MS/s, 16 bits 8 ch. digitizer (analog setup) SIS MS/s, 12 bits 4 ch. digitizer DAQ by IFIC, J. Agramunt Digital PSA Relative efficiency performance Cross-talk between the detectors NEDA test setup BC537 BC501A BaF2

Tests: Preliminary timing 500–200MHz 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. The time resolution is obtained for the SuperBialkalyne PMT with a 60 Co source and for two frequencies 500 MHz (the nominal) and 200 MHz (final NEDA one) FWHM = 1.23ns for CFD at 500 MHz. FWHM = 2.03ns for CFD at 200 MHz. CFD Fermi FWHM = 1.32ns at 500 MHz. FWHM = to be done at 200 MHz

P.A. Soderstrom et al., to be submitted NIM A Pulse shape discrimination for NEDA Tests: PSA Neural Network NN Traditional 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 BC537 and BC501A. + Optimal discrimination over a large energy range -Slower implementation limits counting rate

New materials for neutron detection

Tests of new material at LNL EJ299 The new scintillator EJ299 3’’x3’’ 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 Reactions of interest: – 13 C(α,n) 16 O (2 MeV <E n < 3 MeV) – 22 Ne(α,n) 25 Mg(0.1 MeV <E n < 0.45 MeV) Parameters of interest: neutron counting rate, energy E n, possibly E n (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 2ns Possibility to measure E n (ΔΕ/Ε~10%), needed TOF (pulsed beam or some other time reference)

Some thoughts about Drawbacks: Sensitive to gamma rays BC501A dangerous material – Much less dangerous EJ309 Thresholds 22 Ne(α,n) 25 Mg(0.1 MeV <E n < 0.45 MeV): –100 keV – 7.4 keVee –300 keV – 27 KeVee –500 keV – 57 KeVee E. Dekempeneer et al., (1987). NIM 256(3), 489–498

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, EXOGAM2 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 EXOGAM2 and PARIS Continuous tests at LNL on: –Relative efficiency –Timing –PSA –new materials EJ NEDA will be built in phases: MoU signed March NEDA will be coupled to the NW+AGATA at the AGATA GANIL phase Strong synergies with other neutron communities: MONSTER, DESIR, NEULAND