論文の公開元へ名古屋大学タンデトロンAMS14Cシステムの現状と利用（2019）
概要
A Model 4130-AMS by High Voltage Engineering Europe B.V., dedicated to 14C measurements was delivered to Nagoya University in 1996/97. Acceptance tests of its performance were completed in 1999, and a routine operation started in mid-2000. The number of targets measured was 330, 1430, 2077, 1003, 1,979, 1679, 1772, 1115, 1339, 866, 1300, 1701, 1449, 1634, 1351, 1741, 1156, 466, 900, 1345 and 653 in each year from 1999 to 2019, respectively, 706 from January to May in 2020, and total number of targets measured by the end of May in 2020 is 27,991. The problems of the AMS system in 2019/20 are; (1) Control in the rotation of the wheel loaded with the targets to be measured was out of order. A harmonic drive motor to rotate the wheel looked wrong and it was replaced with a new one; (2) A differential pumping unit (a dry pump, MUP-015-2) in the ion source looked wrong, because attaining the high vacuum in the ion source after target exchange took more time than normal condition. We replaced the dry pump with the new one. It took a shorter time but the attainable high vacuum level in the ion source was no big difference than before; (3) A telemeter card that controls the rotation of the wheel loaded with the targets to be measured was out of order. A capacitor to stabilize a DC+5V supply from the power circuit on the telemeter card was broken and replaced; (4) A light guide pass in the ion source to monitor the control of target movement was completely filled up with aluminum dust fragments. Owing to this disturbance, correct exchange of the targets was not possible. We have removed the dusts and cleaned the ion source, and normal operation was recovered; (5) Adjustment of parget position in X-Y direction was needed for a target to be spattered properly by Cs+ ions to produce C- ions efficiently in the ion source. 9 panto-positions are set on the surface of the graphite target, to keep C- ion productivity high enough for five-day measurements.
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