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ÁŒ¨¸É¥Áž}œ 210.00 nGy/h 419.45 Bq/kg 1.13 ¨³ 0.26 mSv/y ˜µ¤¨Îµ—´ œ°„‹µ„œ¸Ê¥´ŠÅ—ošÎµ„µ¦Áž¦¸¥Áš¸¥ o°¤¼¨
š¸Éŗo œ¸Ê„´ o°¤¼¨š¸ÉÁºÉ°™º°Å—o°Šœ´„ª·‹´¥š´ÊŠÄœÂ¨³˜n µŠž¦³Áš«°¸„—oª¥
‡ÎµÎµ‡´: „´¤¤´œ˜£µ¡‹ÎµÁ¡µ³ —·œ ®´ªª´—¦´ Š¸ÂÁ‹°¦r¤µÁœ¸¥¤¦· » š›·Í(HPGe) °´ ˜¦µž¦·¤µ–¦´Š¸Â„¤¤µ—¼—„¨ºœ(D)
‡nµ„´¤¤´œ˜£µ¡¦´Š¸ ¤¤¼¨ °ŠÁ¦Á—¸¥¤(Raeq) ‡nµ—´œ¸ª´—‡ªµ¤Á¸É¥Š¦´Š¸š¸É ŗo¦´‹µ„£µ¥œ°„¦n µŠ„µ¥ (Hex) ‡nµž¦· ¤µ–
¦´Š¸¥´ŠŸ¨š¸Éŗo¦´‹µ„£µ¥œ°„¦nµŠ„µ¥ž¦³‹Îµže (AEDout)
Abstract
Specific activities of natural (238 U, 232 Th, 226 Ra and 40K) and anthropogenic radionuclides (137Cs) in 160
soil samples collected from 16 districts of Songkhla province, have been measured and evaluated. 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. Gamma ray radioactive standard sources Cesium-137 (Cs-137), Cobalt-60 (Co-60) and Barium-133
(133 Ba) 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 232 Th 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 or 3 hours. It was found that, the soil specific activity ranges from 279.40 – 17523.33 Bq/kg for 40K, 1.19
- 997.27 Bq/kg for 226Ra, 3.84 – 192.98 Bq/kg for 232Th and 0.00 – 24.58 Bq/kg for 137 Cs with mean values of
3149.26 ± 214.09 Bq/kg, 99.48 ± 6.64 Bq/kg, 54.19 ± 5.06 Bq/kg and 1.50 ± 0.76 Bq/kg, respectively. The
absorbed dose rates in air (D), the radium equivalent activity (Raeq ), the external hazard index (Hex) and the annual
effective dose rate (ADE out) due to the calculated specific activities of 40K, 226 Ra and 232 Th were also evaluated and
ranges from 88.63 - 416.67 nGy/h, 177.77 - 807.51 Bq/kg, 0.48 – 2.18 and 0.11 - 0.51 mSv/y with mean values of
210.00 nGy/h, 419.45 Bq/kg, 1.13 and 0.26 mSv/y, respectively. Moreover, all of these values were also compared
with nationally and internationally approved values.
Keywords: Specific Activity, Soil, High-Purity Germanium (HPGe) Detector, Absorbed Dose Rate(D), Radium
Equivalent Activity(Raeq), External Hazard Index(Hex ), Annual Effective Dose Rate (ADEout)
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