Manufacture And Test On Large Area Scintillator Neutron Detector With 2D Position Resolution

Because the price of 3He gas,a very good neutron detection medium,has been rising sharply these years,it is research hotspots to search for new media to replace 3He.In the thesis,a 6LiF/Zn(Ag)scintillation neutron detector with Wave Length Shifting Fiber(WLSF)arrays has been fabricated and its properties was test on neutron beam.Multi-anode PhotoMultiplier Tube(MaPMT)H8500 with 64 channels,produced by Hamamatsu in Japan,has been applied to the neutron detector.And the scintillator of the detector uses AST26139.Electronics and data acquisition is offered by electronics group of the Institute of High Energy Physics(IHEP).The Y-11(200)MS wavelength shifting fibers(WLSFs)are selected to compose fiber arrays.For the detector,the distance between the neighbor fiber cores is 2mm.Double scintillation screens are located between two layers of WLSF arrays.The both ends of each WLSF fiber are coupled to a pixel of MaPMT by air.Signals of electronics output are feed to PC via USB cable.The key component of the neutron detector WLSF,has been selected by experiments.Results show that the performances of Y-11(200)MS fiber from Kuraray company are much better than that of BCF-91 A fiber.The bending loss of the former is just(20.8±0.5)% of the later,and the light conversion efficiency of the former for blue light is(58±7)% higher than that of the BCF-91 A fiber.In detector manufacture,the Y-11(200)MS fibers with 1mm diameter have been used.The properties of the neutron detector were studied with the 252 Cf source of IHEP.The background experiment with 252 Cf source shows that the effective area of the detector is up to 250 mm × 250 mm.Neutron imaging by using cadmium plate with slits indicates that the position resolution of the detector reaches its limited values,2mm.Because of the differences of gain of H8500 channels and discrimination threshold unadjustable,the background of the detector can't be suppressed very well.Using LED as a pulsed light source to study the maximum count rate of the scintillation detector,it can be up to 100±3kHz.By compared with the count rate of 3He tube at neutron beam from China Academy of Engineering Physics(CAEP)in Mian-yang,Sichuan province,the detection efficiency of the neutron detector is(51 ± 5)%(@2.18 ?)when the electronics threshold is set at 0.3V.In conclusion,we have successfully manufactured a scintillation neutron detector with performances of high detection efficiency,good position resolution,and high neutron count rate.It fills a domestic gap in scintillation neutron detector research.And it offers reference for studying on the main detector arrays of High Intensity Powder Diffractometer(HIPD)in China Spallation Neutron Source(CSNS).