Ultrasensitive methods of measuring isotope ratios of heavy elements using accelerator mass spectrometry
| Project/Area Number |
02554003
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
NAKAMURA Masanobu (1992) Kyoto Univ.Dept.Phys.Lecturer, 大学院・理学研究科, 講師 (90025479)
小林 晨作 (1990-1991) 京都大学, 理学部, 教授 (80013465)
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| Co-Investigator(Kenkyū-buntansha) |
KOHNO Masuchika Kyoto Univ.Dept.Nucl.Eng.Instruc., 大学院・工学研究科, 教務職員
OGINO Koya Kyoto Univ.Dept.Nucl.Eng.Instruc., 大学院・工学研究科, 助手 (40026034)
MURAKAMI Tetsuya Kyoto Univ.Dept.Phys.Instruc., 大学院・理学研究科, 助手 (50219896)
TAZAWA Yuji Kyoto Univ.Dept.Phys.Instruc., 大学院・理学研究科, 助手 (60124757)
小林 紘一 (小林 絋一) 東京大学, 原子力総合研究センター, 助手 (70108637)
中村 正信 京都大学, 理学部, 講師 (90025479)
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| Project Period (FY) |
1990 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥18,100,000 (Direct Cost: ¥18,100,000)
Fiscal Year 1992: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1991: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1990: ¥15,200,000 (Direct Cost: ¥15,200,000)
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| Keywords | ACCELERATOR MASS SPECTROMETRY / ISOTOPE RATIO / ULTRASENSITIVE METHODS OF MEASURING / DATING / ENVIRONMENT MEASUREMENT / LONG-LIVED RADIOISOTOPES / 加速器質量分折法 / 重元素 / 加速器質量分析 / 同位体分析 / 微量分析 / 負イオン源 / 加速器制御 |
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| Research Abstract |
An accelerator mass spectrometry (AMS) system based on an 8UDH Pelletron at Kyoto University was developed. Long-lived radioisotopes of ^<36>Cl, ^<41>Ca and ^<129>I were interesting to study for dating and environment measurements. We were starting the AMS program with ^<14>C measurements in order to test and improve the reliability of our AMS system. We introduced a sputter ion source with 59 samples and operated the sample manipulation mechanism manually by monitoring its position with television and linear potentiometers. With x-y slits at the ion source, the beam transmission through the tandem accelerator was stable. The terminal voltage was controlled using ^<13>C_<4+> ions whic were dissociated at the terminal from molecular ions of ^<13>CH^-. ^<14>C ions were counted by a silicon detector. The background peaks of ^<14>N^<4+> and (^7Li_2) ^<4+> ions were separated using a 3 mum thick Al foil in front of the detector. We used sequential injection with slow cycling by varying the magnetic field of the bending magnet. The transmission was measured for ^<12>C and ^<13>C ions and we estimate the transimission for ^<14>C using the stripping efficiency. Sample materials of NBS oxalic acid standard were oxidized and the resulting CO_2 was purified cryogenically in a vacuum preparation system. It was converted to graphite by reducing the CO_2 on Fe catalyst with H_2 gas.
For the ^<36>Cl measurements, we tested the gas ionization chamber as the DELTAE counter in order to separate the isobar (^<36>S) and also tested the electrostatic deflector to reduced the backgroud ions of different charge states.
The graphitized sample of NBS was measured using sequential injection of ^<12>C,^<13>C and ^<14>C ions. Measured ^<14>C/^<12>C ratios show the reproducibility of our AMS system. We will start the research program of ^<14>C measurements and optimize the detector system for heavy elements.
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Report
(4 results)
Research Products
(4 results)
