Trial Manufacturing Study of Charge Spectrometer for Atoms Produced by Alpha-Decay

Research Project

Project/Area Number	01840026
Research Category	Grant-in-Aid for Developmental Scientific Research (B).
Allocation Type	Single-year Grants
Research Field	無機・錯塩・放射化学
Research Institution	Tohoku University
Principal Investigator	YAGI Masuo Tohoku University, Institute for Material Research, Professor, 金属材料研究所, 教授 (10004269)
Co-Investigator(Kenkyū-buntansha)	SHIOKAWA Yoshinobu Tohoku University, Institute for Material Research, Assistant, 金属材料研究所, 助手 (50111307) HARA Mitsuo Tohoku University, Institute for Material Research, Assistant, 金属材料研究所, 助手 (90005918)
Project Period (FY)	1989 – 1990
Project Status	Completed (Fiscal Year 1990)
Budget Amount *help	¥10,000,000 (Direct Cost: ¥10,000,000) Fiscal Year 1990: ¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1989: ¥8,000,000 (Direct Cost: ¥8,000,000)
Keywords	Alpha decay / Charge spectrometer / Charge spectrometry / Electron cloud / Ionization / Perturbation / Shake-off effect / アクチノイド元素 / アルファ放射体 / 壊変生成原子 / 荷電スペクトル / 四重極質量分析計
Research Abstract	If the ejection of alpha particle from the nucleus has no effect on the electronic cloud, the daughter species should have a double negative charge. Whether or not the excess negative charge remained with the product will depend firstly on the effect of nuclear transition on the surrounding electrons, and secondly on the electron affinity of the atom. The perturbation of K-shell of the electronic cloud by emission of an alpha particle differs from the effect of beta decay. Although beta-particle moves with speed considerably in excess of the orbital electron motions, the velocity of alpha is much less than that of electrons in the K-shell. Because alpha is so heavy and moves so slowly, its perturbation of the atomic electrons varies appreciably only in times much longer than the period of their motions. Since a slowly-varing perturbation produces very small effect, probability of exciting or ejecting K-shell electrons is very small. On the contrary, when the velocity of alpha is much g … More reater than those of the outer-shell electrons, excitation and ejection of electrons from these levels may treat in a similar manner to that of beta-decay. The sudden perturbation of the electrostatic environment of these electrons may cause excitation or shake-off of electrons. However, such a ionization due to alpha-decay has not yet been measured by charge spectrometry. In the present study, the trial manufacturing of charge spectrometer for alpha-decay was carried out, and its ability was examined fundamentally. The spectrometer consists of a source volume attached with either irradiation assembly of electrons or that of X-ray and a quadruple mass spectrometer coupled with an evacuation system. The source volume consists of collecting guide rings of eight stages which leads ions in the souree volume into the quadruple mass spectrometer. After the abilities of spectrometer were investigated fundamentally, the charge spectrum of xenon irradiated with X-rays and fragment distributions produced in DBr, HBr, CH_3Br and C_2H_5Br by X-ray irradiation and isomeric transition of bromine-80m were measured as practical applications. It was confirmed that the specific capabilities of the spectrometer were shown in the typical results by the above experiments, and that the initial purpose of the present study was achieved effectively. In further study using tritiated hydrogen, however, the spectrometer was highly contaminated with tritium, and it was found to be difficult to continue the present experiments in a short period of time. Hence, at present, it is forced to used as an ordinary mass spectrometer to decontaminate the tritium. Less