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3Research Assistant, Department of Physics, Faculty of Science, Thaksin University, Songkhla, 90000, Thailand.
4°µ‹µ¦¥rž¦³‹Îµ µ µª·µ¢d ·„r ‡–³ª·š¥µ«µ˜¦r ¤®µª· š¥µ¨´¥š´„¬·– °. Á¤º°Š ‹. Š ¨µ 90000
4Dr., Department of Physics, Faculty of Science, Thaksin University, Songkhla, 90000, Thailand.
Corresponding author: Ú¦«´¡šr : 081-5423598 E-mail:prasong@tsu.ac.th
‡ÎµÎµ‡´ : „´¤¤´œ˜£µ¡‹ÎµÁ¡µ³ °´˜¦µž¦· ¤µ–¦´Š¸—¼—„¨ºœÄœ°µ„µ« „´¤¤´œ˜£µ¡¦´Š¸ ¤¤¼¨Á¦Á—¸¥¤ —´œ¸‡ªµ¤Á¸É¥Š
¦´Š¸š¸É ŗo¦´‹µ„£µ¥œ°„¦nµŠ„µ¥ ž¦·¤µ–¦´Š¸¥´ŠŸ¨š¸Éŗo ¦´˜n°že
Abstract
Specific activity of natural (40K, 226 Ra, 232Th) and anthropogenic radionuclide (137 Cs) in 69 soil samples
collected from 6 districts in Phathalung province, have been measured and analyzed. Experimental results were
obtained by using a high–purity germanium (HPGe) detector and gamma spectrometry analysis system at Nuclear
and Material Physics laboratory in Department of Physics, Faculty of Science, Thaksin University Songkhla
Campus. Gamma ray radioactive standard sources Cesium-137 (Cs-137), Cobalt-60 (Co-60) and Barium-133
(133Ba) were used to calibrate the measurement system. The KCl and two well-known reference materials (RGU-1
and RGTh-1) obtained from the International Atomic Energy Agency were also used to analyze and compute the
40K, 238 U (or 226Ra) and 232Th specific activity in all of the soil samples, respectively. The IAEA/SL-2 was also
used to evaluate the specific activity of 137Cs in all soil samples. The measuring time of each sample is 10,800
seconds. It was found that specific activity range from 148.17-11276.78 Bq/kg for 40K, 5.44-518.45 Bq/kg for
226Ra, 4.46-236.19 Bq/kg for 232Th and 0.00-12.39 Bq/kg for 137 Cs with mean values of 4512.95 ± 226.71 Bq/kg,
153.12 ± 7.20Bq/kg, 86.36 ± 5.76Bq/kg and 1.71 ± 0.80 Bq/kg, respectively. Furthermore, absorbed dose rate in
air (D), radium equivalent activity (Raeq), external hazard index (Hex ), and annual effective dose rate of this area
were also evaluated by using the mean values of specific activities of the 40K, 226 Ra and 232 Th. Moreover, the
experimental results were also compared with Office of Atoms for Peace (OAP) research data, Thailand and
global radioactivity measurement and evaluations.
Keywords: Specific activity, Absorbed dose rate in air, Radium equivalent activity, External hazard index, Annual
effective dose rate
‡ÎµœÎµ
œ·ªÅ‡¨—r„´¤¤´œ˜¦´ Š¸›¦¦¤µ˜·¤¸„µ¦Â¡¦n „¦³‹µ¥°¥¼nš´É ªÅž˜µ¤£µ¡Âª—¨o°¤ °ŠÃ¨„ ¨³¤´„‹³¤¸ °¥¼n
š´É ªÅžÄœ¦¼žÂ˜n µŠÇ šµŠ›¦–¸ ª·š¥µ Ž¹ÉŠ¤¸ °¥¼nĜ—·œ ®·œ ¡º œÊ娳°µ„µ« œ·ªÅ‡¨—r„´¤¤´œ˜¦´Š¸›¦¦¤µ˜·Äœ—·œ
¨³š¦µ¥n ªœÄ®n¤µ‹µ„ 226 Ra ¨³ 238U š¸É¤¸°¥¼n Ĝ°œ»„¦¤¥¼Á¦Áœ¸¥¤ (uranium series ) ¨³ 232 Th Ĝ°œ»„¦¤š°Á¦¸¥¤
(thorium series) ¦ª¤Åž™¹ŠŸ¨Ÿ¨·˜ (product) ¦»nœ¨¼„¦»n œ®¨µœš¸ÉÁ„·—‹µ„„µ¦¨µ¥˜´ ªÄœ°œ»„¦¤µ¦„´¤¤´œ˜¦´Š¸˜nµŠÇ
Á®¨nµœ´Ê œ°¸„¤µ„¤µ¥ ¨³œ°„‹µ„œ¸Ê ¥´Šž¦³„°Åž—oª¥µ¦„´¤¤´œ˜¦´ Š¸š¸É ¤¸°¥¼nĜ›¦¦¤µ˜·°¥¼n ¨oª˜´ÊŠÂ˜n„εÁœ·— °Š