The compact pulsed neutron source facility can play an important role in the research, education, user training, and development of the advanced neutron scattering instruments. The materials for the target, moderator, reflector (TMR) and their configurations must be optimized to get the optimal yield of neutrons with energy in the range of 1 meV to eV order which depends on the proton energy and its nuclear reaction. Several kinds of materials of the TMR, their configurations, and their dimensions are investigated by the Monte Carlo simulation and optimized for developing the compact pulsed neutron source. The results would contribute to the construction of the Compact Pulsed Hadron Source (CPHS) of Tsinghua University.

The Compact Pulsed Hadron Source (CPHS) of Tsinghua University will produce neutrons by the Be(n,p) reaction through bombarding a proton beam with 13MeV/50Hz/1.25mA from a LINAC system on a beryllium target. One of the purposes of this neutron source facility is to provide the neutron scattering capability for characterization of materials, especially soft matters and biological systems. Cold neutrons (wavelength > 4 Å) are essential to characterize the structure of these materials over the length scale of ∼100 nm with good resolution. We discuss the design and optimization of a cold neutron source (CNS) which employs a solid methane moderator for cold neutron generation. The moderator configuration, the associated cryogenic system, and operation conditions will be discussed.