著者

市川 米太 長友 恒人

出版者

奈良教育大学

雑誌

奈良教育大学紀要. 自然科学 (ISSN:05472407)

巻号頁・発行日

vol.23, no.2, pp.3-13, 1974-11

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In an earlier paper of this bulletin, the authors described how the thermoluminescent (TL) method may be an effective one for the dating of ancient pottery and it has an advantage over radiocarbon method. The present paper is concerned with some salient points in the development of the TL technique at our laboratory during the past 10 years. The results recently obtained from the typical potteries are shown, which contain the dating results for a series of shards from Ban-Chiang and those for a series of shards from Nara. The quartz and feldspar embedded in clay matrix have been exposed by the natural radiation since the last heating. The TL emitted from the ancient pottery is a measure of the total dose of this radiation. On the assumption that the natural dose-rate has been constant, the time elapsed since the firing of the pottery is estimated from the accumulated radiation dose and the dose per year. The TL dating used in the present investigation is the method which is known by the name of the inclusion method or the large grain method. For the estimation of the accumulated radiation dose we measured the TL of qualtz and feldspar inclusions with diameters of greater than 0.3 mm. Consequently, we could neglect the contribution from alpha particles which will only penetrate into the inclusions approximately 0.023 mm on average and are typically only from 10 to 20 % as efficient as beta or gamma radiation in the creation of TL. The environmental radiation and the radiation from the pottery itself were measured with CaSO4; Tm TL dosimeter developed by Matsushita Electric Ind. Co., Ltd.