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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.

We experienced severe accident on nuclear power plant at March 2011. We understood now that the radioactivity is one of the most important environments for our mankind. Knowledge and basic experience on radioactivity must be a fundamental curriculum to be taught in the General Education of University. We intended to understand natural radioactivity depend on our common environments. In this paper, we report the result of our trials for measurement of radioactivity in and around the Higashiyama Campus of Nagoya University. Measured activities will be memorized on students as our common exposure., 2011年3月に起こった東京電力福島第一原子力発電所での事故は、これまでの日常生活において、気に留める必要が無かった様々な物理量を、意識の内に持ち込んだ。シーベルトやベクレルの用語が新聞やテレビにあふれる今、放射線量が、気温や二酸化炭素量とともに、人間にとって最も重要な環境評価指標のひとつであることに気づいた。しかし、µSv やbqの単位が新聞やテレビで報道されても、いまひとつ理解に至りにくい。しかし、放射線や同位体に関する基礎的な知識は一般教養として必須のものである。原子力発電所の事故で放出された放射性物質そのものを名古屋で直接観察する事は容易にはできない。しかし、自然界には、ウランやトリウムの娘核種やカリウムの放射壊変に伴う放射線が飛び交い、その量は名古屋大学キャンパス内においても、場所により大きく異なる。その値はどれほどなのか？ 場所により異なる理由は何か？ 測定機器に表示される数値は何を意味しているのか？ についてTAや学生と共に考えた。本報告は、大学初年時学生を対象として企画されている「基礎セミナー」を利用して、『シー ベルト(Sv)で表現される線量当量を体感し、紙面に報道される数値を体で理解する試み』の記録である。, 名古屋大学宇宙地球環境研究所年代測定研究部シンポジウム報告

An AMS system (Model 4130-AMS) dedicated to 14C measurements, built by High Voltage Engineering Europe (HVEE), B.V., The Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests of its performance on carbon isotope measurements were completed in January of 1999, and routine measurements began in mid-2000. Since completion of the acceptance tests in early 1999, we have encountered a lot of troubles with the machine, particularly in 2002. Since the end of 2002, the machine has worked relatively well, expect for minor problems. The standard deviation (one sigma) of the 14C/12C ratio is around ±0.3% to ±0.4% (a bit larger than the uncertainty of about ±0.3% calculated from 14C counting statistics) and that of the corresponding 13C/12C ratio is ±0.03% to ±0.07%, as are tested for HOxII targets. The number of targets measured was 330, 1430, 2077, 1003, 1,979, 1679, 1772, 1115, 1339, 866, 1300, 1701, 1449, 1634, 1351, 1741, 1156 in each year from 1999 to 2015, respectively, and total number of targets measured by the end of 2015 is 23,921. We briefly describe the maintenance processes and application results of the AMS system in 2015. The Tandetron AMS system at Nagoya University worked rather well in 2015, with only minor failures, such as (1) X-Y direction movement trouble of target surface to change sputtering positions, (2) compressed-air-leakage problem of an air cylinder to exchange targets to be measured, (3) unexpected break down of high voltage of accelerator without any sparks, without any specific reasons, (4) ion source cleaning due to shortage of Cs in the container, (5) high temperature problem of the circulating water for cooling down the power supply system for two high-energy mass-analyzing magnets. The error no. (3) above became a serious problem at last in December, because we cannot reset a system diagnostic alarm concerning a high voltage spark at last. It was finally found out that the problem caused by a malfunction of the spark-detector circuit unit, mounted on the top of the accelerator tank. \In 2015, we also carried out many application programs of 14C measurements. The reports are included in this Proceedings volume., 名古屋大学宇宙地球環境研究所年代測定研究部シンポジウム報告

Carbonate hydroxyapatite (CHa) in bone, which is a bone inorganic component, is beginning to be used for 14C dating on cremated bones, because the bones suffering from heat at the temperature of more than 600°C have high crystalline of apatite and are not easily contaminated by exogenous carbon. However, it remains a possibility that a part of carbon in CHa could be exchanged by exogenous carbon derived from fuel and/or atmosphere during heating. It is important, therefore, to reveal the origin of carbon in CHa for reliable 14C dating using CHa. The purpose of this study is to estimate the presence or absence of the possibility of capture of exogenous carbon into CHa during heating by investigating of changes of chemical composition and crystal structure of bones during heating. We conducted a heating experiment using two modem fresh boar bones. The F14C values of bone CHa did not change by heating, even when heating under atmosphere, while the δ13C values changed a little: decreased slightly with increasing heating temperature from 300°C to 750°C, and increased significantly at 900°C. The former decrease could be due to decomposition of carbonate with lower δ13C during heating, while the latter increase could be due to carbon isotopic fractionation and/or take-up of exogenous carbon. The results suggest the possibility of exchange of CHa carbon with carbon in fuel and/or atmosphere during heating., 火葬されて有機成分が残存していない骨に対し、骨の無機成分である炭酸ヒドロキシアパタイト(CHa)を用いた 14C年代測定が有効と考えられる。しかし、遺跡などから出土する火葬骨CHaのδ13C値が低いという報告があ り、火葬中に外来炭素を取り込んだ可能性も考えられる。そのため、加熱による骨の結晶構造や化学組成の変化を調べ、外来炭素の取り込みがないかを明らかにするこ とが、火葬骨CHaの14C年代の信頼性を議論する上で重要となる。本研究では、現生のイノシシ骨の加熱実験を行い、加熱による骨の結晶構造や化学組成の変化を調べた。その結果、大気存在下での加熱でも、骨CHaの14C濃度に変化は見られなかったが、δ13C値は 750℃まで加熱温度が高くなるにつれ減少し、900℃では増加した。しかし、その変化は1-2‰であり、Lanting et al. (2001)によ って報告されている低いδ13C値(-24±3‰)は今回の加熱実験では得られなかった。以上の結果か ら、骨を大気存在下で加熱することが、骨CHaのδ13C値を減少させる要因ではないこと、14C年代測定には影響しないことが明らかとなった。今後さらなる加熱実験を行い、骨CHaへの燃料中炭素の取り込みの有無について調べる予定である。, 名古屋大学宇宙地球環境研究所年代測定研究部シンポジウム報告

Bone collagen, the organic fraction of the bone, is commonly used on 14C dating of bone, while it can not be used for cremated bone because of no remain of collagen. Meanwhile, recent studies have presented that carbonate hydroxyapatite (CHa), the inorganic fraction of the bone, can be used for 14C dating of cremated bone, though the CHa is easily contaminated by exogenous carbon and should be purified by chemical treatment. The purpose of this study is to test the reliability of 14C dating of CHa by using a cremated bone of known-age in Japan. The samples used were the cremated bone, which is considered to be remains of Jokei, a Buddhist monk (AD 1155-1213). We examined whether chemical treatment of the cremated bone with 0.1 M acetic acid for a short time of 1 hour is adequate for removal of secondary carbonate to obtain innate CHa for accurate 14C dating. The CHa in six fragments of the cremated bone showed 14C dates between 1155-1280 cal AD, which are similar with the supposed age. The result indicates the effectiveness of acetic acid treatment and the possibility of accurate 14C dating of CHa by the appropriate chemical treatment., 骨の14C年代測定には、有機成分であるコラーゲンを利用するのが一般的である。しかし、コラーゲンが損失しているため、14C年代測定が困難な骨試料も少なくない。そのような骨試料、特に火葬骨に対して、近年、無機成分の炭酸ヒドロキシアパタイト(CHa)を用いた14C年代測定が試みられている。そこで、本研究では、年代既知の火葬骨に対して、実際に、CHaを用いて信頼性のある14C年代測定が可能かどうかの検証を行った。また、二次的な炭酸塩による汚染を除去するための低濃度短時間の酢酸処理の有効性についても評価を行った。用いた火葬骨試料は、奈良県三郷町の持聖院に所蔵されていた蔵骨器内の骨片である。この人骨は、平安時代末から鎌倉時代にかけて活躍した僧・貞慶（AD1155-1213）の遺骨であるとされている。年代測定の結果、本研究で使用した火葬骨6点から得られた14C年代は1155-1280cal ADという、貞慶の没年と2σの誤差範囲で一致する結果となった。一方、酢酸処理により発生したC02は現代に近い年代を示したことから、本研究で使用した火葬骨は、2次的な炭酸塩等の外来炭素の汚染があったものの、酢酸処理によって効果的に除去された結果、CHaの信頼性のある14C年代測定が可能であったことがわかった。また、真空下における、0.1Mの酢酸による1時間程度の酸処理の有効性も明らかになった。今後、より年代の古い試料や保存状態の異なる試料についても検討を行っていく予定である。, 名古屋大学年代測定総合研究センターシンポジウム報告

An AMS system (Model 4130-AMS) dedicated to 14C measurements, built by High Voltage Engineering Europe (HVEE), B.V., The Netherlands, was delivered to Nagoya University in 1996/97. Acceptance tests of its performance on carbon isotope measurements were completed in January of 1999, and routine measurements began in mid-2000. Since completion of the acceptance tests in early 1999, we have encountered a lot of troubles with the machine, particularly in 2002. Since the end of 2002, the machine has worked relatively well, expect for minor problems. The standard deviation (one sigma) of the 14C/12C ratio is around ±0.3% to 土0.4% (a bit larger than the uncertainty of about ±0.3% calculated from 14C counting statistics) and that of the corresponding 13C/12C ratio is ±0.03% to ±0.07%，as are tested for HOxII targets. The number of targets measured was 330, 1430, 2077, 1003, 1,979, 1679, 1772, 1115, 1339, 866, 1300, 1701, 1449, 1634, 1351, 1741 in each year from 1999 to 2014, respectively, and total number of targets measured by the end of 2014 is 22,765. We briefly describe the maintenance processes and application results of the AMS system in 2014. The Tandetron AMS system at Nagoya University worked rather well in 2014, with only minor failures, such as (1) target exchange trouble, (2) high temperature problem of the circulating water for cooling down the power supply system for two high-energy mass-analyzing magnets, and (3) damage of a diaphragm vacuum pumping system in the ion source stage. In spite of these minor difficulties with the machine, the total number of graphite targets measured was 1741 in 2014, about 400 more in number than that in 2013 (1351)., 名古屋大学年代測定総合研究センターシンポジウム報告