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在使用自制外推电离室(以下简称外推室),绝对测量国产JJ-2型电子静电加速器电子在硅材料深部剂量率实验中,加速器电子束流强度的不稳定将引起外推室所测电离电流的不稳定。有时束流强度不稳造成的电离电流变化量会大于因空腔体积改变所引起的电离电流变化量,致使外推室测量的数据无法进行体积外推,从而失去了外推室测剂量的意义。本实验采取单位束流强度剂最测量方法,在外推室进行测量的每一个极间距离上,由计算机快速同步地采集数十组电离电流和与之相应的束流强度值,剔除粗差后求单位束流强度下电子的平均电离电流值,进而使体积外推得以顺利进行。最后通过有关公式计算出单位束流强度下的电子平均吸收剂量率。
In the use of self-made extrapolation ion chamber (hereinafter referred to as the extrapolation chamber), the absolute measurement of the domestic JJ-2 electron electrostatic accelerator electron in the silicon material dose rate experiment, accelerator electron beam current instability will cause extrapolation chamber measured Ionization current instability. Sometimes the ionospheric current caused by instability of beam intensity will be greater than the change of ionization current due to the change of cavity volume, which makes the extrapolated chamber measured data can not be extrapolated by volume, thus losing the meaning of extrapolating room dose . In this experiment, taking the most measure method of unit beam intensity agent, dozens of sets of ionization current and its corresponding beam intensity value are collected by the computer synchronously at each pole distance measured by extrapolation room. After removing the gross error Determine the unit electron beam current ionization current value, so that the volume extrapolation can be carried out smoothly. Finally, through the relevant formula to calculate the electron beam unit dose intensity under the average absorbed dose rate.