Monte Carlo Simulation And Experiment Measurement Of Neutron Detectors Based On~6Li Isotope

The neutron physics experimental facility of TMSR(Thorium-based Molten-SaltReactor) is a white neutron source with a LINAC of15MeV electron, using15MeVelectron beam bombard a cylindrical tungsten target, through bremsstrahlung and (γ,n)reaction, produces about1MeV peak energy neutrons,after polyethylene/graphitemoderated,which produces neutrons with continuous energies from thermal neutron tofast neutron of15MeV. The facility will be used in key nuclear cross sectionmeasurement of TMSR Th-U cycle and neutron detector study. As neutron flux,spectrometry and detection efficiency are the key factors in nuclear data measurement,In the measurement of total and capture cross-section, the reasonable choice of theneutron such as time of flight (TOF) detectors and gamma ray detectors are crucial forimproving the measurement accuracy of the nuclear data. As one of a particular isotope,6Li has a high thermal neutron cross section, play an important role in the thermalneutron and resonance neutron measurements.So it is very important to research on thescale, and efficiency curve of different neutron detectors.Lithium iodide (6LiI) scintillator detector,lithium fluoride powder(6LiF) andlithium glass with a very high detection efficiency and small size, be used extensively inenvironmental monitoring, homeland security, geological logging, neutron imaging.This work contain the study of simulation and experimental measurement ofneutron detectors based on6Li isotope. On the theoretical aspect: the detectionefficiency of different sizes of6LiI andnatLiI crystals, the detection efficiency of6Liglass scintillation, the detection efficiency of different sizes of LiF, the detectionefficiency of LiI/LiF crystals in combination with plastic scintillation detector, at lastthe penetration of thermal neutron from Thermal reactor of6LiI andnatLiI were allsimulated by Monte Carlo code. On the Experimental aspect: the use of existing sourcesof laboratory conditions, neutron and gamma spectra of neutron detector have apreliminary study, and then through the thermal neutron reactors, they were accurateefficiency calibration. So the theoretical simulation and the actual measurement allshow that the enriched6LiI of10cm thickness is up to90%,while the naturenatLiI70%. The neutrons and gamma rays can clearly distinguish from the amplitudespectrum.They can meet the requirements of the detection efficiency and the amplitudespectrum of neutrons and gamma, will be used as time stop detector in TOF of spectraof neutron measurement and monitoring detector.