Windowless solid hydrogen target
Windowless solid hydrogen target
复制标题
无窗固体氢靶
DOI：
10.1016/s0168-9002(01)00951-2
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发表时间：
2002
影响因子：
1.4
通讯作者：
T. Tsuru
中科院分区：
文献类型：
--
作者：
S. Ishimoto;Toshio Kobayashi;K. Morimoto;I. Nomura;A. Ozawa;S. Suzuki;Y. Takahashi;I. Tanihata;T. Tsuru
一种无窗固体氢靶在RIKEN RI束流设施中成功开发用于RI束流诱导核反应。在与液氦储层直接接触的10mm厚纯铜板中，在孔中可重复生长出高质量的氢晶体。正常氢气在4.7 ~ 7.3 3k时直接在细胞壁上结晶。晶体直径为25mm，厚度选择5或10mm。结晶后，将细胞的侧壁与晶体和细胞板分离，并移至低温恒温器内的偏远位置。因此，晶体在细胞内是自我支撑的，周围没有任何额外的物质。分离过程中未见损伤。当液氦储层为4.2K时，观察到的氢压表明晶体温度为4.3K，与晶体热平衡计算的温度一致。结果表明，储层温度降至3K时，晶体温度无法确定，但晶体温度可以接近储层温度。根据蒸汽压和泵送条件计算氢升华率。如果晶体保持在3K时，升华损失可以忽略不计。
A windowless solid hydrogen target has been successfully developed for RI-beam-induced nuclear reactions in the RIKEN RI Beam Facility. Hydrogen crystals of high quality were grown reproducibly in a cell bored in a 10mm thick pure copper plate which was in direct contact with a liquid helium reservoir. Normal hydrogen gas was crystallized directly on the cell wall between 4.7 and 7.3K. The diameter of the crystal was 25mm and the thickness was chosen to be either 5 or 10mm. After crystallization, sidewalls of the cell were separated from both the crystal and cell plate, and removed to a remote position inside a cryostat. Thus, the crystal was self-supported in the cell without any extra material in its neighborhood. No damage was observed in the separating process. The observed hydrogen pressure indicated the crystal temperature of 4.3K, when the liquid helium reservoir was at 4.2K, in agreement with the temperature estimated from the heat balance in the crystal. It shows that we can put the crystal temperature close to the reservoir temperature, though we could not confirm the crystal temperature when the reservoir temperature was reduced to 3K. Hydrogen sublimation rate was calculated from the vapor pressure and pumping condition. The sublimation loss is negligibly small if the crystal is held at 3K.