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用飞行时间法测量了中国原子能科学研究院重水反应堆热柱中子能谱。脉冲中子束由机械选择器产生,选择器是一个由两片不锈钢中间夹一镉片构成的高速转盘。在转盘边缘对称处有两个狭缝,当中子束通过任一个狭缝时,由光电二极管和光敏三极管组成的线路给出中子起飞信号。中子探测器~3He正比计数管距转盘97cm。数据采集系统主要由时-幅转换器和多道幅度分析器组成。实验测得飞行时间谱,将其转换成能谱并进行了探测器效率、飞行时间零点、空气衰减、能量分辨率修正。由于热柱孔道内有一个50cm长的硅过滤器,所以中子能谱偏离典型的麦克斯韦分布。
The time-of-flight method was used to measure the thermal column neutron energy spectrum of the heavy water reactor of China Institute of Atomic Energy. The pulsed neutron beam is generated by a mechanical selector. The selector is a high-speed turntable consisting of a cadmium plate sandwiched between two stainless steel plates. There are two slits symmetrically on the edge of the turntable. When the neutron beam passes through any one of the slits, the line consisting of the photodiode and the phototransistor gives the neutron takeoff signal. Neutron detector ~ 3He proportional counter tube turntable 97cm. Data acquisition system is mainly composed of time-amplitude converter and multi-channel amplitude analyzer. The time-of-flight spectrum was measured experimentally, converted into energy spectrum, and the detector efficiency, flight time zero, air attenuation and energy resolution correction were performed. The neutron energy spectrum deviates from the typical Maxwellian distribution due to a 50cm long silicon filter in the hot column cell.