出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Over the past two years, we have developed and tested an efficient, large-area, sub-mm spatialresolution,
fast-neutron imaging system with time-of-flight spectroscopic capability. The
detector is based on a 30 mm thick scintillating fiber screen viewed by a time-gated optical
readout, described in another contribution to this conference.
In order to analyze key parameters affecting detector performance, Monte-Carlo simulations
using the GEANT 3.21 code were performed. To characterize the intrinsic spatial resolution of
the scintillating fiber screen, a neutron transmission image of a steel mask containing a series of
slits with various widths, pitch and thicknesses was simulated. The point spread function of the
scintillating fiber screen was determined by exposure to an infinitesimally narrow neutron beam,
incident perpendicular to the surface, calculating the spatial distribution of the energy deposited
by the protons in the screen fibers. The energy distribution of the (n,p) protons produced in the
screen and the amount of scintillation light subsequently created were also calculated. All the
above simulations were performed for 3 neutron energies (2, 7.5 and 14 MeV).
For the detector tests performed at the PTB cyclotron, the neutron beam-line geometry was
simulated as accurately as possible, in order to calculate the contribution of neutron scatter as
well as gamma rays and to enable a comparison with the experimental results.
