Development of Self-TOF Neutron Detector and Estimation of Neutron Scattering Cross Section

最近，在日本东北大学的回旋加速器设施和RRC的回旋加速器设施上，发展了20到210 MeV能量范围内用薄Li-y靶轰击质子的准单能中子场。在这项工作中，我们研制了一台自飞行时间中子探测器，用于测量利用这些中子场的中子散射截面。探测器由否决权闪烁体、辐射体、启动闪烁体和停止闪烁体组成。利用两个闪烁体信号(启动和停止)的时间差测量了辐射体内反冲质子的飞行时间，并估算了注入的中子能谱。在这项工作中，在三个回旋加速器上测量了探测器对高能中子的响应特性，并研究了最适合于散射中子测量的探测器结构和测量条件。测量了中子在石墨靶上的散射，得到了65 MeV中子对碳的30度散射的双微分截面。此外，该探测器还可以测量正向带电粒子的产生截面，得到了C、Al和Cu的0级(n，px)和(n，dx)反应截面。

Recently, quasi-monoenoergetic neutron fields using thin Li-y target bombarded proton in an energy range between 20 and 210 MeV were developed at cyclotron facilities of CYRIC(Tohoku Univ.), TIARA(JAERI, Takasaki) and RRC(RIKEN). In this work, a Self-TOF neutron detector was developed to measure the neutron scattering cross sections using these neutron fields. The detector consists of a veto scintillator, a radiator, a start-scintillator and a stop-scintillator. The flight times of the protons recoiled in the radiator are measured using the time difference of the signals from the two scintillators (start and stop), and the injected neutron energy spectra are estimated in the analysis.In this work, characteristics of the detector response to high energy neutrons were measured at the three cyclotron facilities, and detector structure and measurement conditions, which is the best for the scattering neutron measurement, were investigated. The neutrons scattered at graphite target were measured and the double differential cross section (DDX) of scattering for 65 MeV neutron at 30 degree for carbon was obtained. Moreover, it was clarified that the charged particle production cross sections at forward direction could also be measured using the detector, and (n, px) and (n, dx) reaction cross section at 0 degree for C, Al and Cu were obtained.