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根据厚靶原理,用各种浓度的氯化铀酰水溶液作为厚靶,用已确定表面积的铂片作为吸收体浸没于铀溶液中,测定热(慢)中子引发~(235)U裂变碎片~(89)Sr,~(91)Y,~(140)Ba,~(141)Ce,~(144)Ce在各铀浓度的水溶液中的射程值。在含铀量为0.16％—6.2％的范围内,铀浓度对射程测定值没有明显影响。因此,可以认为当铀溶液足够稀时,裂片在铀溶液中的射程很接近于它们在水中的射程。实验得出该五种裂片在水中的射程分别为:R_(Sr-90)=2.39+0.04mgcm~(-2),R_(Y-91)=2.355±0.09mgcm~(-2),R_(Ba-140)=1.92+0.07mgcm~(-2),R_(Ce-141)=1.91±0.12mgcm~(-2),R_(Ce-144)=1.84+0.10mgcm~(-2)。为了估计裂片在铂片中反散射的影响,进行了以不锈钢片作为吸收体的实验(用硝酸铀酰水溶液作为厚靶),结果表明反散射的影响不大。本工作为测定裂片在液体中的射程提供了一个较简便的方法。
According to the principle of thick target, various concentrations of aqueous uranyl chloride solution were used as thick targets, and immersed in uranium solution with a platinum plate with a defined surface area as an absorber. Thermal (slow) neutron-induced ~ (235) U fission fragments ~ (89) Sr, ~ (91) Y, ~ (140) Ba, ~ (141) Ce and ~ (144) Ce in aqueous solution of each uranium concentration. In the range of 0.16% -6.2% of uranium content, uranium concentration has no significant effect on the measured range. Therefore, it can be assumed that when the uranium solution is sufficiently dilute, the range of the lobes in the uranium solution is very close to their range in water. The experimental results show that the ranges of the five kinds of lobes in water are R_ (Sr-90) = 2.39 + 0.04mgcm -2, R_ (Y_91) = 2.355 ± 0.09mgcm -2, R_ Ba-140 = 1.92 + 0.07mgcm -2, R Ce-141 = 1.91 ± 0.12mgcm -2 and Ce-144 = 1.84 + 0.10mgcm -2. In order to estimate the influence of the backscattering of the slides in the platinum sheet, an experiment using stainless steel sheet as an absorber (using a uranyl nitrate aqueous solution as a thick target) showed little effect of backscattering. This work provides a simpler way to determine the range of slits in a liquid.