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七十年代,缓发中子测铀技术受到极大重视,并得到了引人注目的发展。这是可在现场进行非破坏性分析铀含量的新技术。为了应用这种技术,我们在高压倍加器上用脉冲调制的~3T(d,n)~4He反应产生的14MeV中子照射铀矿模拟井,然后用浓缩~(10)B的BF_3计数管测量铀裂变产物放出的缓发中子,进行室内测铀井模拟试验。试验中观测到,随着14MeV中子通量的增加,用直流高压工作的BF_3计数管缓发中子计数与14MeV中子通量监督器计数之比值不是常数,而是逐渐增加;和通常工作的BF_3计数管相比较,它的坪曲线和脉冲高度分布谱也有明显畸变。这与直流高压工作的BF_3计数管也受到大量14MeV中子照射真接有关。这种现象被称为BF_3计数管的辐照效应。在其它中子实验中,常在距产生中子的靶室适当远处放一个BF_3计数管进行中子通量相对测量,当BF_3计数管靠近中子靶室时,也曾观测到BF_3计数管的辐照效应。
Seventies, delayed detection of neutron uranium technology has received great attention, and has been a remarkable development. This is a new technology that allows on-site non-destructive analysis of uranium content. In order to apply this technique, we simulated uranium wells with 14MeV neutrons generated by the pulsed ~ 3T (d, n) ~ 4He reaction on a high pressure doublet and then measured with a BF_3 counter tube that concentrated ~ (10) B Uranium fission products released slow neutrons, uranium wells for indoor test simulation. It has been observed experimentally that with the increase of 14 MeV neutron flux, the ratio of the BF_3 counting retarding neutron count to the 14 MeV neutron flux supervisor working at DC high pressure is not a constant, but gradually increasing; and the usual work Compared with BF_3 counting tube, its flatness curve and pulse height distribution spectrum also have obvious distortion. This work with the DC high-pressure BF_3 counter tube is also a lot of 14MeV neutron irradiation true connection. This phenomenon is called the BF_3 counter radiation effect. In other neutron experiments, a BF_3 counter tube is often placed at a suitable distance from the neutron producing target chamber to measure the relative neutron flux. When the BF_3 counter tube is near the neutron target chamber, the BF_3 counter tube Irradiation effect.