Neutron Detector Simulations for Fast Neutrons with GEANT4
Neutron Detector Simulations for Fast Neutrons with GEANT4 Brian Roeder LPC Caen 01/31/20 1 Motivation Want to design a next generation neutron detector array.
Array to detect neutrons over a large energy range (1 MeV < En< 150 MeV) with good energy and angular resolution. Would like the capability to detect multiple neutron events for breakup experiments and -multiple Nmultiple N decays. 01/31/20 2 Development Issues Response of detector modules Detection
efficiency (materials) -N discriminationN discrimination Minimization of Cross Talk Geometry of array setup Development of offline cross talk rejection Optimization of detector array for different types of experiments 01/31/20
3 Monte Carlo Sims. With GEANT4 GEANT4 has the following advantages: Built-N discriminationin, 3D Visualization of detector and events! Tracking of all particles before and after detection (important for Cross Talk simulation).
Realistic design of detectors with all materials; easy to change materials without rewriting whole simulation. 01/31/20 4 Overview of Sim. Validation Create a simulation in GEANT4 of an existing detector module with measured detection efficiency DEMON Test neutron scattering models provided by GEANT4 vs. DEMON efficiency and other
simulations (e.g. MENATE). If necessary, modify existing scattering models in GEANT4 to obtain a more realistic simulation DEMON I. Tilquin et al. NIM A365, (1995), Pg. 446 01/31/20 MENATE P. Dsesquelles et al., NIM A307 (1991) 366 5 The MARGOT simulation Tube of BC-N discrimination501A liquid scintillator with DEMON
module dimensions Can measure energy deposited, position of neutron hit, and time of flight Currently converts energy loss of ions by hand into electron-N discriminationequivalent (MeVee) energy using [Cec79] equations. Tracks all particles produced in neutron interactions. Can produce different neutron beams Detection Threshold set at 0.5 MeVee. 01/31/20 R.A. Cecil et al., NIM 161 (1979) Pg. 439
6 Standard GEANT4 neutron elastic scattering LEElastic scattering model 01/31/20 Points Cyril Varignon these LPC Caen (1999) 7
Improvement with JENDL data set 01/31/20 8 Addition of Standard Inelastic Model Corrects for drop in efficiency after 20 MeV. 01/31/20 9
Evaluation Over-N discriminationestimates efficiency between 2 and 5 MeV. Under-N discriminationestimates efficiency after 25 MeV. Does not produce heavy-N discriminationion residuals, gammas from (n,n) events. Seems to randomly produce d,t,, etc. Would like a more-N discriminationrealistic simulation with the KNOWN organic scintillator reactions! 01/31/20 10
Inelastic Neutron Scattering for En>4 MeV Mostly inelastic scattering, transfer, and breakup reactions on 12C. The GOOD: 12C(n,p)12B and 12C(n,)9Be The BAD: 12C(n,3)n and 12C(n,np)11B The UGLY: 12C(n,n ) and 12C(n,2n)11C Cross sections for these reactions are known, have been used in other
simulations e.g. MENATE. A. Del Guerra NIM 135 (1976) Pg. 337 01/31/20 M. Labiche these LPC Caen (1999) 11 GEANT4 NeutronHP model Includes inelastic reactions specifically with reference to total cross sections. Data and parameterizations available from thermal energies to 20 MeV with
the G4NDL. With a few modifications, can be extended to 100 MeV by adding cross section data from MENATE LEFastNeutron Model 01/31/20 12 Comparison MENATE vs. GEANT4 LEFastNeutron 01/31/20
13 Results of LEFastNeutron model 01/31/20 14 What about the 1 to 4 MeV efficiency?
01/31/20 15 Results Have developed a Monte Carlo simulation in GEANT4 for BC-N discrimination501A scintillator. Reasonable agreement between simulation and measured efficiency More realistic representation of inelastic reactions with LEFastNeutron model 01/31/20
16 Future Work Test how GEANT4 simulates angular distributions of scattered neutrons Study Cross-N discriminationTalk for different neutron energies. Develop setup of future array and test cross section rejection schemes. 01/31/20
17 Special Thanks Marc Labiche for initial help with GEANT4. Franck Delaunay for providing the MENATE calculations presented. Other collaborators : Nigel Orr, Miguel Marqus, Benoit Laurent, writers of GEANT4. We acknowledge the financial support of the European Community under the FP6 "Research Infrastructure Action-N discriminationStructuring the European Research Area" EURISOL DS Project contract no 515768 RIDS. The EC is not liable for the use that can be made of the information contained herein.
01/31/20 18 FIN 01/31/20 19 Discussion Is there some other way to improve
result at low energy other than conic beam spot or adjustment of cross sections? Is it proper to leave out alpha reactions to improve simulation of efficiency? Suggestions from meeting participants on how this simulation can be improved. 01/31/20 20
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