WAVELENGTH OF SCINTILLATION LIGHT FROM XENON-DOPED LIQUID ARGON AND ITS APPLICATION TO PHOTOIONIZATION DETECTORS

掺氙液氩闪烁光的波长及其在光离子化探测器中的应用

• 批准号: 04640392
• 负责人: MASUDA Kimiaki
• 金额: $ 1.34万
• 依托单位: SAITAMA COLLEGE OF HEALTH
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640392/
• 关键词: Rare Gas Liquid; Scintillation; Photoionization; Radiation Detector

Ionization yield for alpha particles in liquid Ar at 10kV/cm is about 10% of the initially prodeced charge. This is due to recombination of ions and electrons in alpha tracks where ionization density is large. If photoionization molecules are doped in liquid Ar, they will be ionized by scintillation photon from recombination and the ionization yield will increase. The quantum efficiencies of photoionization are 60% for allene and 20% for trimethylamine. The similar effect is seen in liquid Xe. The quantum efficiencies of trimethylamine and triethyl-amine are 80% in liquid Xe. To investigate the reason for this difference in the quantum efficiencies in liquid Ar and liquid Xe, we have considered the relation between the wavelength of scintillation light and the ionization potential of molecules doped in the liquids, especially the excess energy.The wavelength of sintillation photon in liquid Ar is 130nm and that in liquid Xe is 175nm. When Xe is doped in liquid argon, the wavelength shifts form 130nm to 175nm for the Xe concentration of 10 to 200ppm. Based on this fact, we have measured the quantum efficiencies of the photoionization and studied the relation to the wavelength of the scintillation photon. As a result, the quantum efficiency of trimethylamine in Xe-doped liquid Ar decreases with increase of the Xe concentration, that is, with decrease of the excess energy. Therefore, the difference in quantum efficiencies in liquid Ar and that in liquid Xe cannot be explained by the excess energy. Instead, the cage effect is the most reliable candidate for the reason.

在10KV/cm时，α粒子在液态Ar中的电离产额约为初始产生电荷的10%。这是由于离子和电子在阿尔法轨道上的复合，那里的电离密度很大。如果在液态Ar中掺杂光致电离分子，它们将被复合产生的闪烁光子电离，从而提高电离产额。丙二烯的量子电离效率为60%，三甲胺的量子电离效率为20%。在液体Xe中也可以看到类似的效果。在液体Xe中，三甲胺和三乙胺的量子效率为80%。为了研究液体Ar和液体Xe的量子效率差异的原因，我们考虑了闪烁光的波长与液体中掺杂分子的电离势的关系，特别是过剩能量，液体Ar和液体Xe中的闪烁光子波长分别为130 nm和175 nm。当Xe掺杂到液态Ar中时，当Xe浓度在10~200ppm时，波长从130 nm移动到175 nm。基于这一事实，我们测量了光致电离的量子效率，并研究了它与闪烁光子波长的关系。结果表明，随着Xe掺杂浓度的增加，三甲胺在液体Ar中的量子效率降低，即过剩能减小。因此，液体Ar和液体Xe中量子效率的差异不能用过剩能量来解释。相反，笼子效应是最可靠的原因。