液体闪烁体探测器测量皮秒激光脉冲中子源能谱

Neutron spectrum measurement for picosecond laser pulse neutron source experiment with liquid scintillator detector

在"星光Ⅲ"实验装置上开展皮秒激光脉冲中子源实验,使用液体闪烁体探测器测得较好的中子信号,利用飞行时间法获得中子的能量/时间分布,通过示波器电压时间积分与阻抗之比得到不同能量段的电荷值。建立液体闪烁体探测器Geant4计算模型,通过实际打靶情况与标定情况下液体闪烁体探测器出光口收集到的可见光光子数之比,结合标定的灵敏度数据,获得液体闪烁体探测器对不同能量中子的灵敏度。计算得到源发射的中子能谱,能量在1 MeV以上的液体闪烁体探测器方向测得的中子产额为1.04×108 sr-1。

The picosecond laser pulse neutron source experiment was demonstrated on Xingguang-Ⅲ facility. A good neu- tron signal was measured by liquid scintillator detector. The neutron energy distribution with time was obtained by time-of-flight method, and the charge between different energy intervals was acquired by the ratio of the integral of oscilloscope voltage and time to oscillator input resistance. Geant4 calculation model for liquid scintillator detector under experimental and calibration cases were established, and the neutron sensitivity was obtained by the ratio of the collected optical photons. Neutron energy spectrum for picosecond laser pulse neutron source was calculated, and the neutron yield below 1 MeV in the direction of liquid scintillator detector was 1.04×10^8 sr^ -1.