เอกสารการประชุมวิชาการและเสนอผลงานวิจัย มหาวิทยาลัยทักษิณ ครั้งที่ 19 2552 - page 1359

„µ¦ž¦³»¤ª·µ„µ¦Â¨³Áœ°Ÿ¨Šµœª·‹´¥¤®µª·š¥µ¨´¥š´„¬·– ‡¦´ÊŠš¸É 19 ž¦³‹Îµže 2552
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Research Center and Pattani Rice Research Center) were studied and evaluated. The high-purity germanium
detector (HPGe) and gamma spectrometry analysis system in Nuclear and Material Physics Laboratory of Physics
Department Faculty of Science Thaksin University was used to perform the measurement. The Cs-137 and Co-60
radioactive standard sources were used to calibrate the measurement system and the IAEA-152 radioactive
contaminated milk source was also used to compare and calculate the specific activities of potassium-40 ( 40K).
The measuring time of all rice samples is 10,000 seconds. It was found that the specific activities of potassium-40
in rice samples from Nakhon Si Thammarat Rice Research Center ranged from 123.16-162.33 Bq/kg with mean
values of 146.014±9.65 Bq/kg. The specific activities of potassium-40 in rice samples from Krabi Rice Research
Center ranged from 140.11-197.33 Bq/kg with mean values of 160.723 ± 11.21 Bq/kg. The specific activities of
potassium-40 in rice samples from Phatthalung Rice Research Center ranged from 94.64-199.54 Bq/kg with mean
values of 162.93±11.89 Bq/kg. The specific activity of potassium-40 in rice samples from Pattani Rice Research
Center ranged from 85.97-297.37 Bq/kg with mean values of 161.83 ±11.62 Bq/kg. Moreover, the average value
of specific activity of potassium-40 in all rice samples was also compared with OAP data and the average values
of potassium-40 in some varieties of food around the world. The result was found in normal level.
Keywords: Specific activity; Potassium-40; High-purity germanium detector (HPGe); Gamma ray spectrometry
analysis system
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