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An AMS system (Model 4130-AMS) dedicated to 14C measurements, built by High Voltage Engineering (HVE), B.V., the Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests of its performance on carbon-isotope-ratio measurements were completed in January of 1999, and routine measurements began 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 and 900 in each year from 1999 to 2017, respectively, and total number of targets measured by the end of December 2017 is 25,287. We briefly describe the maintenance processes of the AMS system in the year of 2017. The Tandetron AMS system at Nagoya University has encountered several problems in 2017. They are; (1) two big sparks seriously damaged the solid state RF driver for the high voltage generation, and the AMS system could not supply the high voltage of 2.5 MV used for 14C measurements. We replaced a damaged coil at the final part of the high-voltage power supply unit with a new coil; (2) a power supply unit for loading electrical current to correctly adjust the current for the recombinator magnet was in trouble. A resistance unit located at the end of current supply circuit was burnt out. We replaced it to a new one; (3) after a high-voltage spark, we could not apply high voltage to the accelerator. A control circuit board of supplying high voltage was checked and it was found out that the electrical board B-5-41-205-0001 was out of work. We replace the board to one repaired previously; (4) During the usual measurement of a graphite target, 12C3+, 13C3+ and 14C3+ decreased gradually in the last half of its measurement time of 30 minutes. The plus ion beam intensity of 13C3+ decreased from 200nA to 5nA in ten minutes, without any changes on its target current (corresponding to 13C- current). We first checked all the parameter values of the power supplies to the AMS system, but we could not find any changes from their nominal values. We finally concluded that something wrong has happened inside the accelerator tank, and decided to open the tank after 5 years of previously opening the tank. Owing to these problems, we can process only 900 graphite targets in 2017. In 2017, we also have carried out some application programs of 14C measurements at Nagoya University. Some of the results are included in this Proceedings volume.

We, the members of the Division for Chronological Research at the Institute for Space-Earth Environmental Research at Nagoya University, held a regional contribution program for elementary and junior high school students on August 4–5, 2016: “Investigation of past solar activity and the paeloclimate change from tree annual rings and varved lake sediments.” Thirty-five students and six of their parents observed natural samples to experience earth and archaeological sciences. The first day began with a lecture on how tree annual rings and varved lake sediments can be used to reveal the paleoclimate. After the lecture, the students took part in several hands-on experiments on sedimentology. On the second day they travelled to the Wakasa area by bus and visited the Wakasa-Mikata Jomon Museum to learn about the pre-historic Jomon lifestyle and culture by observing remains from the Jomon Period excavated from the Torihama shell mound. Later in the day they took a cruising observation expedition across Suigetsu Lake, Mikatagoko to observe unique varved sediment layers on a lakebed revealing paleoclimate change dating back 70,000 years. Finally, they observed genuine sediment cores at the Fukui Prefectural Satoyama-Satoumi Research Institute. The program ended a success. The post-program questionnaire shows that the participants enjoyed the program and learned many new things., 年代測定研究部においては、平成28年度総長裁量経費地域貢献事業として、平成28年8月4日（木）と5日（金）の2日間に亘り、小学5年生から中学3年生まで35名を対象とした体験学習「樹木年輪・年縞堆積物から過去の太陽活動、地球の古気候を探る」を実施した。初日は名古屋大学で講義・実習を、2日目はバスで福井県若狭三方五湖に出向き、若狭三方縄文博物館の見学、水月湖の野外調査、ならびに福井県里山里海湖研究所において年縞堆積物の見学を行った。全体的に内容を詰めすぎた感はあるが、参加者は楽しみながら体験学習には取り組んでいた。アンケート結果が示すように、本事業の目的である“小・中学生に自然科学・地球科学・文化財科学等の面白さを伝える”ことは十分に果たされ、地域社会へ貢献できたと考えられる。

An AMS system (Model 4130-AMS) dedicated to 14C measurements, built by High Voltage Engineering (HVE), B.V., the Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests on its performance on carbonisotope- ratio measurements were completed in January of 1999 and routine measurements began in mid-2000. The numbers of targets measured from 1999 to 2016 were: 330, 1430, 2077, 1003, 1,979, 1679, 1772, 1115, 1339, 866, 1300, 1701, 1449, 1634, 1351, 1741, 1156, and 466, respectively (24,387 were measured by the end of June 2016). We briefly describe the maintenance processes for the AMS system in 2016. The Tandetron AMS system at Nagoya University encountered several serious problems in 2016. First, the high voltage of the accelerator broke down frequently for no clear reasons. Any sparks happened before these voltage downs. Second, a compressor for the cryo-pumping system stopped suddenly. Parts for maintaining the pump system are no longer supplied by the manufacturer, leaving us no choice but to replace the cryo-pumping system with a turbomolecular pumping system. Third, ion source cleaning had to be conducted due to a shortage of Cs in the container. Fourth, the excessively high temperature of the circulating water used to cool down the power supply system for two high-energy mass-analyzing magnets forced us to replace the system with a magnet power supply system cooled by air. Fifth, a power supply unit for the servo-amplifier controlling the motor for target exchanging function was found to be out of order. Replacement with a spare unit corrected the problem. Six, two big sparks seriously damaged the solid state RF driver for the high-voltage generation, rendering the AMS system incapable of applying the high voltage of 2.5 MV used for 14C measurements. We replaced a damaged coil at the final part of high-voltage power supply for the repair. As a consequence of these numerous problems, were only able to process 466 graphite targets in 2016. We also carried out a number of application programs for 14C measurements at Nagoya University in 2016. Some of the results are reported in these Proceedings.