Speaker
Mr
John Watts
(physicist)
Description
A Geant4 simulation of the Advanced Neutron Spectrometer (ANS) will be described. ANS uses a volume of vinyltoluene scintillator with embedded scintillating glass fibers composed of 20% Li2O-15% MgO-64.4%SiO2-0.6%Ce2O3 with the lithium being 95% Li-6. Neutrons would be captured in the glass which has different scintillation characteristics in terms of spectral output and timing from vinyltoluene scintillator. The capture interaction here is
n+Li-6->alpha+triton
where the triton energy is 2.734 MeV and the alpha energy is 2.105 MeV. To reach energies where this interaction is probable the neutron must be at near thermal energies having lost energy through elastic scattering in the vinyltoluene scintillator. The approach in ANS is to identify the unique light pulse associated with a neutron capture event in the glass fiber and use the total light produced earlier in the vinyltoluene scintillator as a measure of primary neutron energy deposited in the detector volume.
A GDML description of the ANS geometry and the appropriate materials was constructed for input into a Geant4 simulation tailor to transport neutron and describe the response of the various parts of the detector in detail. A key part of the simulation is the description of the optical characteristics of the scintillator material, the scintillator volume surface characteristics, and the optical coupling between the scintillator and the photomultiplier tube.
Summary
A Geant4 simulation of the Advanced Neutron Spectrometer (ANS) will be described.
Primary author
Mr
John Watts
(physicist)
