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处液体AR中α颗粒的电离产量约为最初产生的电荷的10％。这是由于离子密度较大的α轨道中离子和电子的重组。如果将光离子分子掺杂在液体AR中，则将通过重组而闪烁的光子电离，电离产量将增加。艾琳娜的光电离量量效率为60％，三甲胺的量子效率为20％。在液体XE中也可以看到类似的效果。三甲胺和三乙基胺的量子效率在液体XE中为80％。为了研究液体AR和液体XE量子效率的这种差异的原因，我们考虑了闪烁光的波长与掺杂液体中的分子的电离电位之间的关系，尤其是多余的能量。在液体中为130nm，液体中的Xe为175nm。当Xe在液体氩气中掺杂时，波长向10至200ppm的Xe浓度形成130nm至175nm。基于这一事实，我们测量了光离子化的量子效率，并研究了与闪烁光子波长的关系。结果，随着XE浓度的增加，三甲胺在XE掺杂液体AR中的量子效率降低，即多余能量的降低。因此，液体AR的量子效率和液体XE中的量子效率的差异不能用多余的能量来解释。相反，由于原因，笼子效应是最可靠的候选人。