Neutron%20Detector%20Simulations%20for%20Fast%20Neutrons%20with%20GEANT4

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Neutron Detector Simulations for Fast Neutrons
with GEANT4

• Brian Roeder
• LPC Caen
• 5/18/2007

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• GOALS of Beta-N meeting in Caen 27/02/2007
• Discuss status of available detector arrays
• Discuss current developments (both here and
  elsewhere DESPEC, )
• Identify technical know-how in different labs
• Identify and define possible collaborations (FP7
  (2007)??)
• Define goals, contributions, timelines,

NAO Réunion 02/07
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• Programme
• Introduction Goals, ideas, etc for a new array
  - Nigel Orr
• Status of DESPEC neutron detector array work -
  Daniel Cano Ott
• Two-neutron detection with TONNERRE - Miguel
  Marqués
• Simulations using GEANT4 MENATE - Brian Roeder
• Status of the Neutromania project - Franck
  Delaunay
• Digital electronics developments at LPC - David
  Etasse
• Future Plans to be decided by the end of the year
  for SPIRAL2
• Discussion of how to go forward, interests and
  possible contributions from different labs, test
  experiments, etc

NAO Réunion 02/07

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Motivation

• Want to design a next generation neutron
  detector array.
• Array to detect neutrons over a large energy
  range (1 MeV lt Enlt 150 MeV) with good energy and
  angular resolution.
• Would like the capability to detect multiple
  neutron events for breakup experiments and
  ?-multiple N decays.

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Development Issues

• Response of detector modules
• Detection efficiency (materials)
• ?-N discrimination
• Minimization of Cross Talk
• Geometry of array setup
• Development of offline cross talk rejection
• Optimization of detector array for different
  types of experiments

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Monte Carlo Sims. With GEANT4

• GEANT4 has the following advantages
• Built-in, 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.

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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
MENATE P. Désesquelles et al., NIM A307 (1991)
366
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The MARGOT simulation

• Tube of BC-501A 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-equivalent (MeVee) energy using
  Cec79 equations.
• Tracks all particles produced in neutron
  interactions.
• Can produce different neutron beams
• Detection Threshold set at 0.5 MeVee.

R.A. Cecil et al., NIM 161 (1979) Pg. 439
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Standard GEANT4 neutron elastic scattering

• LEElastic scattering model

Points Cyril Varignon these LPC Caen (1999)
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Improvement with JENDL data set
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Addition of Standard Inelastic Model

• Corrects for drop in efficiency after 20 MeV.

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Evaluation

• Over-estimates efficiency between 2 and 5 MeV.
• Under-estimates efficiency after 25 MeV.
• Does not produce heavy-ion residuals, gammas from
  (n,n?) events. Seems to randomly produce d,t,?,
  etc.
• Would like a more-realistic simulation with the
  KNOWN organic scintillator reactions!

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Inelastic Neutron Scattering for Engt4 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
M. Labiche these LPC Caen (1999)
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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

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Comparison MENATE vs. GEANT4 LEFastNeutron
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Results of LEFastNeutron model
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What about the 1 to 4 MeV efficiency?
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Results of Efficiency Study

• Have developed a Monte Carlo simulation in GEANT4
  for BC-501A scintillator.
• Reasonable agreement between simulation and
  measured efficiency
• More realistic representation of inelastic
  reactions with LEFastNeutron model

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Angular Distributions

• 4? - perfect neutron detector.

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Angular and Energy Distributions

• Hydrogen Carbon Elastic Scattering
• Note that most of the higher energy neutrons
  scatter from Carbon

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Results

• Input Total Cross Sections NOT reproducible
  (about 30 50 low, depending on energy)
• Detector Response questions for hydrogen
  scattering (large proton peak)?

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Near future

• Comparing angular distributions with experimental
  published data on differential cross sections for
  neutron scattering on hydrogen, carbon.
• Go to Geant school in Paris (June 4th-8th).

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Future Work

• Develop a simulation in either GEANT4 or edit
  some other code to use for neutron detectors (may
  mean developing own physics process).
• Study Cross-Talk for different neutron
  energies.
• Develop setup of future array and test cross talk
  rejection schemes.

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Special Thanks

• Marc Labiche for initial help with GEANT4.
• Franck Delaunay for providing the MENATE
  calculations presented.
• Other collaborators Nigel Orr, Miguel Marqués,
  Benoit Laurent, writers of GEANT4.
• We acknowledge the financial support of the
  European Community under the FP6 "Research
  Infrastructure Action-Structuring 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.

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FIN
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Discussion

• Suggestions from meeting participants about what
  should eventually be included in simulations.