| Autor: |
Yuki Tosaki, Taichi Miura, Hiroshi Matsumura, Ming He, Yasuo Nagashima, Kimikazu Sasa, Keisuke Sueki, Kotaro Bessho, Tsutomu Takahashi, Riki Seki |
| Rok vydání: |
2007 |
| Předmět: |
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| Zdroj: |
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 259:41-46 |
| ISSN: |
0168-583X |
| DOI: |
10.1016/j.nimb.2007.01.313 |
| Popis: |
With the current AMS system on the 12UD Pelletron tandem accelerator at the University of Tsukuba, we are able to measure the long-lived radioisotopes of 14 C, 26 Al, 36 Cl and 129 I by employing a molecular pilot beam method that stabilizes the terminal voltage with 0.1% accuracy. Several major improvements have been made to increase the sensitivity of the AMS system to 26 Al and 36 Cl radioisotopes. For 26 Al-AMS, the ions extracted from the ion source have been changed from Al − to AlO − by using an Al 2 O 3 target sample. In addition, 26 MgO − molecular ions are used as a pilot beam to control the terminal voltage through slit current feedback. Also, a fully-stripping AMS technique is used to achieve an effective detection limit of better than 5 × 10 −15 for the 26 Al/ 27 Al ratio. For 36 Cl-AMS, the terminal voltage has been increased from 9 MV to 10 MV, thereby increasing the energy of the 36 Cl 9+ beam to 100 MeV. This energy increment helps us to get a clearer separation between 36 Cl and 36 S in a new Δ E − E detector. In addition, the yield of 36 Cl 9+ is increased by 1.5 times as a result of the higher ion energy at the terminal stripper foil. The standard deviation of the fluctuations of the 36 Cl/ 35 Cl ratio is within ±2%, and the effective detection limit is better than 2.0 × 10 −14 . |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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