This work shows a study of the effect of the non-uniformity of photocathode response on the energy resolution of plastic scintillators optimized for pulse-shape discrimination. The studies were performed with Hamamatsu R7600U-200 and R9779 photomultiplier tubes. The pulse-height and pulse-shape spectra were obtained for a small piece of radon-222 loaded plastic scintillator positioned at different places on the photocathode. We show that alpha spectra can be approximated well with a normal distribution if the non-uniformity of the photon response of the photocathode is minimized. In the cases when the non-uniformity cannot be minimized, we propose an analytical function which describes the shape of the alpha peaks well under a variety of conditions. A possible effect of the non-uniformity of the photocathode response on the primary activity measurements by liquid scintillation counting is highlighted.

这项工作展示了光电阴极响应的不均匀性对针对脉冲形状辨别进行优化的塑料闪烁体的能量分辨率的影响的研究。研究使用 Hamamatsu R7600U-200 和 R9779 光电倍增管进行。对于放置在光电阴极不同位置的一小块载有氡 222 的塑料闪烁体，获得了脉冲高度和脉冲形状光谱。我们表明，如果光电阴极的光子响应的不均匀性被最小化，则 α 光谱可以很好地近似为正态分布。在不能最小化不均匀性的情况下，我们提出了一个分析函数，它可以很好地描述各种条件下的 alpha 峰的形状。