ROGER CABALLERO-FOLCH Universitat Politècnica de Catalunya 26 de febrer de 2013 NUSTAR ANNUAL MEETING GSI Darmstadt, Germany Beta dELayEd Neutron (BELEN) detector status

Detection system Previous versions used at JYFL and GSI – Design and analysis/results status Contents Previous versionsNew designsDetection system New designs and conclusions 1

Detection system Previous versions used at JYFL and GSI – Design and analysis/results status Contents Previous versionsNew designsDetection System New designs and conclusions 2 Detection system

β delayed neutron emission 3 Previous versionsNew designsDetection System Detection system

3 He counters as detector The detection of the neutron is based on an indirect method: the detection of the products of the reaction of the neutron with 3 He counters: 3 He + n  3 H + 1 H keV Other reactions: 10 B + n → 7 Li* + 4 He keV 7 Li* → 7 Li keV Ion beam n n n Polyethylene moderator Proportional 3 He counter Silicon β decay detector CounterGasMaximum length (mm) Effective length (mm) Maximum diameter (mm) Effective diameter (mm) Gas pressure (atm) Cathode material 2527 LND inc 3 He / 10 / 8 Stainless Steel 4 Previous versionsNew designsDetection System Detection system Noise Neutron signal

5 Electronic chain for data acquisition and signal processing Analog system: Trigger Digital system: Triggerless Digital Data Acquisition System (DDAS) J. Agramunt & IFIC team The electronic chain of the acquisition system operates independently of the other systems of the experiment and detectors along the beamline. It only needs to synchronize the timestamp. Previous versionsNew designsDetection SystemDetection system

Previous versions used at JYFL and GSI – Design and analysis/results status Contents Previous versionsNew designsDetection system New designs and conclusions 6 Previous versions

7 Tests and experiments with BELEN detector Neutron number N GSI:S410 “Measurement of β-delayed neutrons around the 3 rd r-process peak” C. Domingo- Pardo et al. PERFORMED, September 2011 GSI: S323 “Beta-decay of very neutron-rich Rh, Pd, Ag nuclei including the r- process waiting point 128 Pd”. F. Montes et al. PERFORMED, September 2011 Z=28, N=50; JYFL (2009, 2010 & 2013) I162 “Delayed neutron measurements for advanced reactor technologies and astrophysics” JL Taín JYFL. Expected 2013 B.Gomez-Hornillos et al. NIM in progress (2009 exp) Z=50, N=82 Previous versionsNew designsDetection systemPrevious versions Background measurements at GSI (2010) and LSC Canfranc (2011) D.Jordan et al. Astr.Phys Vol.42, Feb 2013, p.1–6

Support structure requirements: Hold and transport 650 Kg Allow access to the beam hole Movable in Z for fine placement Table + tray movable on “z” on rails Polyethylene matrix hold together and can be lifted as a single unit. Polyethylene: 10 cm thick vertical slices assembled => 90 x 90 x 80 cm3 ~650 Kg detector Fixed support Moving tray BELEN design for JYFL experiments 8 Previous versionsNew designsDetection systemPrevious versions

JYFL experiment 2009 & BELEN He counters at 20 atm 1 ST ring: 8 counters at 11 & 9.5 cm 2 nd ring: 12 counters at 20 & 14.5 cm Average efficiency: 27% & 35% (5MeV) Dimensions: 50x50x80 cm 3 + shielding (90x90x80 cm 3 ) Diameter holes: 2.75 cm Central hole radius: 5.5 cm 9 Previous versionsNew designsDetection systemPrevious versions

S410/S323 experiments at GSI (2011). Design & efficiency. BELEN-30: 20 3 He (20 atm) & 10 3 He (10 atm) Inner ring (10 counters): 29 cm Outer ring (20 counters): 37 cm Efficiency (1keV-1MeV) ~40% Average up to 5MeV ~ 35% Central hole radius: 11.5 cm (SIMBA) Previous versionsNew designsDetection systemPrevious versions 252 Cf neutron source detection efficiency (M.Marta):  MCNPX simulation: (34.5±0.2)%  Triggerless DACQ (IFIC) in MBS : (35.4±0.8)%  Analog branch: (25.5±0.9)% (electronics) Silicon Implantation Beta Absorber (SIMBA) 10

Results and ongoing analysis S410 experiment Previous versionsNew designsDetection systemPrevious versions 11 R.Caballero-Folch, C.Domingo-Pardo et al. Hg Au Pt Tl Pb Bi Po At Rn 211 Hg 215 Tl

Results and ongoing analysis S410 experiment Previous versionsNew designsDetection systemPrevious versions 12 R.Caballero-Folch, C.Domingo-Pardo et al.

Results and ongoing analysis: Previous versionsNew designsDetection systemPrevious versions Counts Time β-neutron (ms) 13 Performance test time correlation between neutron and β-decay for 213 Tl R.Caballero-Folch, C.Domingo-Pardo et al.

Detection system Previous versions used at JYFL and GSI – Design and analysis/results status Contents Previous versionsNew designsDetection system New designs and conclusions 14 New designs

Recent improvements for BELEN design  The number of 3He counters has been duplicated and their pressure changed from 20 atm to 8 atm. The cost of this improvement is around €.  New MC simulations for future BELEN versions to perform more experiments at JYFL (IGISOL trap) and the design with AIDA (changes on central hole radius).  Planarity (flat efficiency) optimization to different energy ranges up to 2MeV or 5MeV.  GEANT4 simulations are being done to compare MC simulations and the correlation has been checked. 15 Previous versionsNew designsDetection systemNew designs

BELEN versions designed Name 3 He counters Pressure (atm) Experiment 2 MeV 5 MeV Average efficiency Central hole radius (cm) BELEN-2020 JYFL [1.60]27%5.5 BELEN-2020 JYFL [1.60]35%5.5 BELEN & 10GSI [1.70]35 %11.5 (SIMBA) BELEN & 10JYFL %-39%5.5 BELEN & 10DESPEC %-34%8 (AIDA) Observe: Central hole, num. counters & planarity 16 max(neutron efficiency) min(neutron efficiency) To define the efficiency flatness for a range of neutron energies Previous versionsNew designsDetection systemNew designs 5MeV 2-5MeV

BELEN design for JYFL Radius of central hole: 5.5cm. Neutron energy range 100 keV – 5 MeV Planarity optimization Name 3 He countersPressure (atm)Ratio 2MeVRatio 5MeV Average Efficiency Central hole radius (cm) BELEN & % total Previous versionsNew designsDetection systemNew designs

BELEN design for JYFL Name 3 He countersPressure (atm)Ratio 2MeV Average Efficiency Central hole radius (cm) BELEN & % total Radius of central hole: 5.5cm. Neutron energy range 100 keV – 2 MeV Efficiency optimization Previous versionsNew designsDetection systemNew designs

BELEN design for JYFL Previous versionsNew designsDetection systemNew designs Radius of central hole: 5.5cm. Efficiency Vs planarity optimization 1MeV 5MeV

New BELEN design in progress for AIDA 20 Name 3 He countersPressure (atm)Ratio 2MeVRatio 5MeV Average Efficiency Central hole radius (cm) BELEN & %8 (AIDA) total Optimized for neutron energy range 100 keV – 5 MeV Radius of central hole: 8 cm Planarity optimization Previous versionsNew designsDetection systemNew designs

21 New BELEN design in progress for AIDA Name 3 He countersPressure (atm)Ratio 2MeV Average Efficiency Central hole radius (cm) BELEN & %8 (AIDA) Optimized for neutron energy range: 100 keV – 2 MeV Radius of central hole: 8 cm total Efficiency optimization Previous versionsNew designsDetection systemNew designs

Summary of design parameters Define the energy range of the neutrons to optimize the desired flat efficiency Number of counters available  Polyethylene matrix Radius of central hole  Implantation detector and beamsize Knowledge of the estimation neutron background to decide the shielding Support structure. 22 Previous versionsNew designsDetection systemNew designs

BRIKEN RIKEN) meeting 23 Previous versionsNew designsDetection systemNew designs  IFIC – UPC – CIEMAT – MSU – Edinburgh – GSI – RIKEN – Tennessee  Analysis of the facility to perform experiments with BELEN + AIDA at RIKEN  Discussion of what kind of experiments can be done and regions to explore.  Possibility of a campaign of measurements in the near future  Conclusions:  Interest of all parts involved  Possibility to increase BELEN efficiency with RIKEN 3 He counters

Conclusions (I)  MC simulations indicates that the overall neutron detection efficiency depends on the 3 He pressure and the number of counters (among other variables).  The number of counters is more significant than gas pressure. (Reason of change of the 21 counters at 20atm to 42 at 8atm)  The inner ring gives the maximum efficiency but for lower energies.  The position of the outer ring is determinant to evaluate: A)the efficiency of the higher energy to optimize B)the neutron background and the shielding design due to the thickness of the polyethylene around the crown.  New experiments will be done with 42 counters at 8 atm (UPC) + 10 counters at 10 atm available (GSI). 24 Previous versionsNew designsDetection systemNew designs

Conclusions (II) BELEN is a 4π neutron detector designed to study β delayed neutron emission Laboratory tests and several successful experiments performed (Barcelona, JYFL, LSC - Canfranc and GSI). The efficiency of the previous configurations has been validated experimentally with 252 Cf sources and some reference isotopes. Flat efficiency is obtained up to neutron energies of 5 MeV Average efficiency of 34% for 8 cm central hole (AIDA) for neutron up to 5 MeV Average efficiency of 45% for 8 cm central hole (AIDA) for neutron up to 2 MeV Neutron efficiency calibration at PTB next June 2013 Proposal approved at JYFL for this year. TDR: Ongoing, expected to include calibrations at PTB improvements presented 25 Previous versionsNew designsDetection systemNew designs

BELEN detector team Work supported by the Spanish Ministry of Economy and Competitivity under contract FPA C03-03 UPC (Barcelona) R.Caballero-Folch, F.Calviño, G.Cortès, A.Poch, C.Pretel, A.Riego, A.Torner Old members: M.B.Gómez-Hornillos, V.Gorlychev IFIC (València) J.Agramunt, A.Algora, C.Domingo-Pardo, D.Jordan, J.L.Taín GSI (Darmstadt – Germany) I.Dillmann, A.Evdokimov, M.Marta CIEMAT (Madrid) D.Cano-Ott, T.Martínez, E.Mendoza, A.García-Ríos

Host Lab requirements for BELEN. Details in documentation. 2013/14: Set-up at S4 in combination with AIDA (Optimization tests )  Beam 238 U primary beam at 900MeV/u 2x10 9 intensity (10 shifts)  Space 25 m 2, background, readout -and acquisition systems, time, correlations,(10 days each year)  10 visitors for preparation of tests, online analysis, etc. 2017: Final set-up at S4 with AIDA  Beam 238 U primary beam at 900MeV/u 2x10 9 & 2x10 10 intensity  Space 25 m 2, installation and final test prior to commissioning (14 days)  10 visitors for commissioning preparation, online analysis, etc. 2018: COMMISSIONING (20 visitors expected) General:, DACQ & MBS system experts, Internet connections and offices for visitors, Mass storage. 27 Previous versionsNew designsDetection systemNew designs

+1 Triggerless digital data acquisition system: Struck digitizer modules (SIS3302): provide time-stamps very versatile for time correlations Negligible dead-time when compared to analog systems Increase the efficiency. Flexibility for large time correlation (fundamental to obtain correlations with all neutron and to change the gates offline) Allows to correct some experimental effects, e.g. To reduce neutron background from uncorrelated neutrons Being developed at IFIC (València-Spain) Digital Data Acquisition System (DDAS) Previous versionsNew designsDetection system

+2 Experimental hall for background measurements at GSI Previous versionsNew designsDetection system

+3 Experimental hall for background measurements at LSC Previous versionsNew designsDetection system D.Jordan et al. Astr.Phys Vol.42, Feb 2013, p.1–6

+4 BELEN design for JYFL experiments (2009 & 2010) Prototype designed for JYFL 2009 with 20 counters Penning Trap (High purity Beam) Previous versionsNew designsDetection system

+5 BELEN design for JYFL experiments (2009 & 2010) Previous versionsNew designsDetection system MCNPX simulation efficiency

+6 BELEN design for GSI experiments 2011 Previous versionsNew designsDetection system MCNPX simulation efficiency

Polyethylene shielding Rings of 3 He proportional counters R1=12.5 cm and 8 counters, R2=18.5 cm and 12 counters. Polyethylene matrix Beam hole r=5 cm Neutron source Developed by V.Gorlychev and B.Gomez at UPC-Barcelona BELEN first designs and geometry The geometry design is based in two rings. The aim is to have a flat efficiency in the energy range of interest (100 keV – 5 MeV). +7 Previous versionsNew designsDetection system

Other designs proposed 3 crowns with 16 counters each at 10 & 8 atm 3 crowns with 16 counters each at 4 atm Total 96 counters Old simulation not optimized +8 Previous versionsNew designsDetection system