基于光电倍增管的核电子学前端系统噪声研究

Research Based on PMT of NEFE System Noise

核电子学前端噪声是设计核电子学前端必须考虑的重要问题,如何确定核电子学前端噪声界限,提高信噪比是前端设计必须关注的问题。从核电子学前端系统(探测器(光电倍增管)、前置放大器和滤波成形电路)入手,通过2个不等式建立了核电子学前端系统噪声上界、下界问题和核电子学前端噪声模型,同时给出核电子学前端系统噪声上界。研究表明,电荷灵敏前置放大器噪声下界与频带无关;核电子学前端系统噪声上界与给定条件下信号频带宽度成正比。

In the design of Nuclear Electronics Front End(NEFE),the NEFE noise is the important issue that should be taken into consideration,it should pay great attention to the problems that how to determine the limitation of NEFE noise and improve the signal to noise ratio in NEFE design.In the paper,from the aspects of NEFE,including prober(the photomultiplier tube),the preamplifier and filter shaping circuit,the NEFE noise model is established and noise limitation problem of NEFE is solved by two inequalities.The analysis and calculate show that the lower-limitation of Charge Sensitive Preamplifier(CSA)is independent of frequency.At the same time,the upper-limitation of NEFE is in proportion with the bandwidth of signals in the given condition.