The Construction And Testing Of Gamma-ray Total Absorption Facility And Monte-Carlo Simulation Of Neutron Monitor

In order to measure(n,γ) cross section accurately,China Institute of Atomic Energy(CIAE) is now developing a Gamma-ray Total Absorption Facility(GTAF). This Facility which has high gamma detection efficiency,good time resolution and good energy resolution is able to obtain the higher precision of neutron capture cross section measurement.In this thesis,the history of several facilities which was designed to measure the neutron capture cross section is reviewed,and The measuring principle and each part of GTAF is introduced too.In this thesis,the packing process of single detector is described.We tested the performance of single detector,including time resolution,energy resolution and long term stability,and completed various kinds of testing after all single detectors were installed.We found some new problems and solved them.This effort guaranteed proper functioning of each single detector.In this thesis,the experiment of the first(n,γ) cross section measurement on HI-13 accelerator in July 2008 is introduced.This experiment was also the first complete testing of GTAF.Because of some limited conditions,there was a high background.Preliminary analysis report indicated that the reason was that we did not install neutron dump.Neutron beam hits the concrete wall directly,producing a large scattering background.Our group is now installing a new neutron dump to solve this problem before next experiment.The detection efficiency of the lithium glass detector which is used as a neutron beam monitor in GTAF(Gamma-ray Total Absorption Facility) was simulated by Geant4.The neutron detection efficiency of the lithium glass was obtained between 10 keV and 1 MeV.Some factors which affect the efficiency were analyzed..A plan to measure the detection efficiency of the neutron monitor was proposed at last.