论文标题
为超级kamiokande gadolinium项目开发硫酸硫酸盐
Development of Ultra-pure Gadolinium Sulfate for the Super-Kamiokande Gadolinium Project
论文作者
论文摘要
本文报告了大约13吨硫酸盐八水合物的开发和详细特性，$ \ rm gd_2（\ rm so_4）_3 \ cdot \ cdot \ rm 8H_2O $，该$ $ $ $ $ $ $ $在2020年夏季溶解为超级kamiokande（SK）。 SO_4)_3\cdot \rm 8H_2O$ on DSNB searches and solar neutrino observation and confirm the need to reduce radioactive and fluorescent impurities by about three orders of magnitude from commercially available high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$.为了产生超高纯度$ \ rm gd_2（\ rm so_4）_3 \ cdot \ cdot \ rm 8h_2o $，我们开发了一种方法来消除氧化物中的杂质，gd $ _2 $ _2 $ o _ $ _3 $，由酸溶解，溶剂溶液萃取和pH Controlsess，紧随其后的过程。 ICP-MS和HPGE检测器分析了所有生产的超高纯度$ \ rm gd_2（\ rm so_4）_3 \ cdot \ rm 8H_2O $ $。由于HPGE探测器的测量时间很长，我们采用了几个地下实验室来进行并行测量，包括西班牙的LSC，英国的Boulby和日本的Kamioka。在生产的上半年中，发现测得的批处理纯度与规格一致。但是，在后半部分，$ \ rm gd_2（\ rm so_4）_3 \ cdot \ rm 8h_2o $包含一个数量级$^{228} $ ra，而不是预算的平均污染。这与原材料GD $ _2 $ o $ _3 $的相应特征相关，其中存在本质上大的污染。基于它们对SK物理学的适度影响，它们仍被引入检测器中。为了减少$^{228} $ ra的下一阶段GD加载到SK，已成功建立了一个新的过程。
This paper reports the development and detailed properties of about 13 tons of gadolinium sulfate octahydrate, $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$, which has been dissolved into Super-Kamiokande (SK) in the summer of 2020. We evaluate the impact of radioactive impurities in $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ on DSNB searches and solar neutrino observation and confirm the need to reduce radioactive and fluorescent impurities by about three orders of magnitude from commercially available high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$. In order to produce ultra-high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$, we have developed a method to remove impurities from gadolinium oxide, Gd$_2$O$_3$, consisting of acid dissolution, solvent extraction, and pH control processes, followed by a high-purity sulfation process. All of the produced ultra-high-purity $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ is assayed by ICP-MS and HPGe detectors to evaluate its quality. Because of the long measurement time of HPGe detectors, we have employed several underground laboratories for making parallel measurements including LSC in Spain, Boulby in the UK, and Kamioka in Japan. In the first half of production, the measured batch purities were found to be consistent with the specifications. However,in the latter half, the $\rm Gd_2(\rm SO_4)_3\cdot \rm 8H_2O$ contained one order of magnitude more $^{228}$Ra than the budgeted mean contamination. This was correlated with the corresponding characteristics of the raw material Gd$_2$O$_3$, in which an intrinsically large contamination was present. Based on their modest impact on SK physics, they were nevertheless introduced into the detector. To reduce $^{228}$Ra for the next stage of Gd loading to SK, a new process has been successfully establised.
