论文标题
掺杂氟化钙的单晶的生长和表征
Growth and characterization of thorium-doped calcium fluoride single crystals
论文作者
论文摘要
我们已经成长$^{232} $ th：caf $ _2 $和$^{229} $ th：caf $ _2 $单晶，用于调查vuv laser-actible-vuv laser-actible-cossible-cossible of vuv laser acter-cossible of vuv laser coss of $^{229} $ th的第一个核激发状态。尽管达到$^{229} $ th的极度稀缺（和放射性），但与已建立的商业或科学生长过程相比，我们的晶体量缩小了100倍。我们在3.2毫米直径的种子单晶上使用垂直梯度冻结方法，带有2毫米钻孔的口袋，里面装满了共沉淀的CAF $ _2 $：THF $ _4 $：PBF $ _2 $ _2 $粉末，以种植单晶。 $ 4 \ cdot10^{19} $ cm $^{ - 3} $的浓度已通过$^{232} $ th实现，并具有良好的（$> $ 10％）VUV传输。但是，$^{229} $ th的固有放射性在固化后驱动了放射性诱导的解离和辐射损伤。两者都导致VUV传输的退化，将$^{229} $ th浓度限制在$ <5 \ cdot10^{17} $ cm $ $^{ - 3} $。
We have grown $^{232}$Th:CaF$_2$ and $^{229}$Th:CaF$_2$ single crystals for investigations on the VUV laser-accessible first nuclear excited state of $^{229}$Th. To reach high doping concentrations despite the extreme scarcity (and radioactivity) of $^{229}$Th, we have scaled down the crystal volume by a factor 100 compared to established commercial or scientific growth processes. We use the vertical gradient freeze method on 3.2 mm diameter seed single crystals with a 2 mm drilled pocket, filled with a co-precipitated CaF$_2$:ThF$_4$:PbF$_2$ powder in order to grow single crystals. Concentrations of $4\cdot10^{19}$ cm$^{-3}$ have been realized with $^{232}$Th with good ($>$10%) VUV transmission. However, the intrinsic radioactivity of $^{229}$Th drives radio-induced dissociation during growth and radiation damage after solidification. Both lead to a degradation of VUV transmission, limiting the $^{229}$Th concentration to $<5\cdot10^{17}$ cm$^{-3}$.
