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Charred material is widely used for radiocarbon (14C) dating in archaeological and palaeoenvironmental studies. Reliable 14C dating requires appropriate chemical treatment to remove post-deposition contamination, especially humic acid, from the charred material. This study compared two pre-treatment methods: Acid-Base-Acid (ABA) treatment and Acid-Base-Oxidation with Stepped-Combustion (ABOx-SC) treatment, in order to examine the effectiveness of decontamination. The ABA-treated environmental charcoal yielded younger 14C dates than the ABOx-treated samples, probably owing to the effects of remaining organic contaminants bound to the edges of the charred material's molecular structures, which were produced by the original pyrolysis. Oxidation treatment can preferentially remove humic acid contaminants, which remained after NaOH treatment. Therefore, the ABOx treatment can more effectively and efficiently remove exogenous humic acid than the ABA treatment. Furthermore, stepped combustion procedure can remove remained contaminants after chemical treatment, such as exogenous organic component and atmospheric CO2 absorbed during samples treatment. Therefore, the ABOx-SC treatment of the charcoal samples can lead a most reliable 14C age for the "old" (especially >30 ka) samples, which are susceptible to contaminants., 炭化物は14C年代測定の有力な試料であり、考古学ならびに古環境の分野で広く利用されている。信頼性のある14C年代を与えるには、炭化物が埋没中に取り込んだ外来炭素成分(特に腐植酸)を適切な試料処理で除く必要がある。本稿では、炭化物の試料処理の違いによる14C年代の違いについて報告する。同一埋没炭化樹木試料に対しABA法、ABOx法の化学処理を行った結果、ABA法では外来腐植酸が試料中に残存していること示唆された。これは炭化物分子に化学的に結合した形で試料中に存在する腐植酸はNaOH処理では除けないことによると考えられる。一方、二クロム酸カリウム溶液による処理を加えたABOx法では、NaOH処理後に残存した腐植酸を優先的に酸化分解するため、効果的かつ効率的に腐植酸を除去できると考えられる。段階加熱処理(SC処理)では、化学処理後に残存した外来有機成分ならびに一連の処理過程で取り込んだ可能性がある現代大気中CO2による汚染を除去する方法として有効と考えられる。したがって、僅かな外来炭素の汚染の影響を大きく受ける古い試料(特に3万年前以前の試料)において、ABOx法に段階加熱処理を加えたABOx-SC法は、外来炭素成分の除去法として最も有効であると言える。, 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

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, particulayly 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 in each year from 1999 to 2013, respectively, and total number of targets measured by the end of 2013 is 21,024. We briefly describe the maintenance processes and application results of the AMS system in 2013. The Tandetron AMS system at Nagoya University worked well in the early four months of 2013, with only minor failures. On 10th May, a noise from the accelerator tank became large, almost similar to the large noise generated on 24th October in 2012. The noise in 2012 was generated from the broken bearing mounted in the power generator that supplied electric power to a terminal turbo-pump mounted inside the tank. It took almost one month to replace it to a new one. So, this time soon opened the tank and checked inside the tank, but could find no special objects that might have generated the noise. Since we could not find the source of the noise, and the noise generated in the normal atmospheric pressure was not so large, we have decided to operate the machine under the small but explicitly existing noise. However, at a pressure of 6.5 bar by SF6 gas, the noise became far bigger and we could not operate the machine. We opened the tank again checked every parts inside the tank more carefully, and finally found out that the noise is generated from the timing belt connecting the power motor at the high-energy end and rotating rod which is transferring mechanical power to the generator used for turbo-molecular pomp operation. The belt was a bit too lose and swinging between the two gear wheels during transferring mechanical power. We tightened the belt and the noise disappeared. It took totally two month to notice the source of the noise. On 22nd October, a big noise was generated again from the tank. This time, we also noticed that the terminal voltage was not stable. At the same condition of high-energy power supply, the terminal voltage readout was a bit low than the normal condition, and the readout decreased with time. We considered that the generating voltmeter (GVM) for measuring the high voltage of the accelerator is in the wrong, and decided to replace it to a new one. We replace it and readout of the high voltage became perfect. Owing to these difficulties with the machine, the total number of graphite targets measured was 1351 in 2013, about 300 smaller in number than that in 2012 (1634)., 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

From July 31, 2013 through August 1, we held a workshop of the dendrochronology for primary and secondary students in Center for Chronological Research, Nagoya University. Ten children and two protectors participated in this workshop. They experienced fundamental experiment of the dendrochronology. In addition, they attended various lectures about the tree ring. They were able to decide the date of the experiment samples. They appreciated these experiments and lectures., 2013年7月31日-8月1日に，名古屋大学年代測定総合研究センターは，小中学生のための「年輪年代法体験学習」を開催した.この体験学習には10名の小中学生と2名の保護者が参加した.参加者は，年輪年代法の基礎実験を体験し，あわせて樹木年輪に関する様々な講義を受講した.全ての参加者が，実験試料の年代決定を成功させた.参加者はこの体験学習の内容を高く評価した., 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

We experienced a severe accident at the Fukushima Daiichi Nuclear Power Plant in March2011. We have understood now that we need to keep alert on radiation exposure in daily life.Knowledge and basic experience on radioactivity must be included in a fundamental curriculumof general education in universities. As a part of the First Year Seminar at Nagoya University, weand the students intended to measure and learn dose of natural radiation from various sources inour common environments. In this paper, we report the radiation exposure of examinee in theirhometown as well as radiation dose measured in and around the Higashiyama Campus of theuniversity. We expect the students to remember their experiences and the approximate amount ofexposed dose in daily life.

An AMS system (Model 4130-AMS) dedicated to14C 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 in each year from 1999 to 2012, respectively, and total number of targets measured by the end of 2012 is 19,674. The Tandetron AMS system worked well in the early half of 2012, with only minor failures. In September, a noise became large from the 12C-beam chopper, in the recombinator system, owing to the problem of a ferro-fluid-feedthrough, which had been used since June, 2008. We have replaced the ferro-fluid feedthrough to a new one. Soon after the chopper problem, the turbo molecular pump (TMP) in the recombinator system was damaged with the bearing of the rotating fan. We sent the pump to the supplier for repair. Because of the broken bearing, the rotating fan was seriously damaged, and we must purchase a new one. On 24th October, a large noise was generated from inside of the accelerator tank. We decided to open the tank and check the parts inside. The problem was also a bearing mounted in the power generator that supplies electric power to a terminal turbo-pump mounted inside the tank. We can get a new generator in a few weeks, because HVEE possessed one for spare by chance. We purchased it and replaced the damage generator on November. After tank opening, inner surfaces of the accelerator tank absorbed water in the atmosphere, we spent much time to remove water vapor from SF6 insulator gas. We had experienced twice of high voltage sparks, but no detectable damage occurred with the accelerator system. We could have restarted 14C measurements at around mid of December. Owing to these difficulties with the machine, the total number of graphite targets measured was 1634 in 2012, smaller in number than that in 2010 (1701), but a larger than in 2011 (1449)., 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