Status and Applications of a Tandetron AMS System at Nagoya University in 2020

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Other Title
  • 名古屋大学タンデトロンAMS14Cシステムの現状と利用（2020）

Abstract

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, 653 and 1123 in each year from 1999 to 2020, respectively, and total number of targets measured by the end of 2020 is 28,408. The problems in 2020 are; (1) instability of C- beam intensity was a big problem for high statistical 14C measurements. Intensities of C- beam gradually decreased to 1/5 from the begging of 14C measurements in about 15 hours. We could not increase the beam intensity any more, even increasing Cs sputtering ions by heating up the Cs reservoir temperature. We tried to shut the ion source down and power on again, but not successful. However, the ion source was opened and cleaned to successfully recover the ion beam intensity. We applied this method for routine 14C measurements, although it wasted a lot of time; (2) the power supply for the recombinator magnet was out of order. The control of DC current for the magnet did not work well. We replaced a power transistor on the circuit board to repair it; (3) a plunger unit to grasp the target for loading and unloading it to the sputtering position was out of order. The four fingers of the plunger were partly broken and could not grasp targets firmly to move them from carrousel to the sputtering position and back. We replaced it to a new one; (4) because of instability of DC voltage of about 90 [V] supplied for a Y- steerer in the ion source, with the fluctuation of about ±5 [V], C- beam suffered instability in the direction of the beam. A part of the C- beam even hits the wall of the beam line. The power supply for the Y-steerer was repaired; (5) a step of initialization to start up the target handling in the ion source could not work well. A target movement control by computer was out of order. We replaced a X-motion motor that could be broken, and changed 6 units of light-guide cable for communication of signals to control the end parts of the ion source unit. In particular, the replacement of lightguide cables was effective for the successful handling of the targets.

Journal

  • 名古屋大学年代測定研究

    名古屋大学年代測定研究 5 65-74, 2021-03

    Division for Chronological Research, Institute for Space‒Earth Environmental Research, Nagoya University

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