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1. ˜¦ª‹—¼ž¦·¤µ–ŜئÁ‹œÁ®¨ª (liquid nitrogen ; LN 2 ) š¸Éčo®¨n°Á¥Èœ®´ªª´— ªnµ¤¸Á¡¸¥Š¡°˜n°„µ¦Äo
Šµœ®¦º°Å¤n ™oµÅ¤nÁ¡¸¥Š¡°˜o°ŠšÎ µ„µ¦Á˜·¤ÅœÃ˜¦Á‹œÁ®¨ª„n°œÄo®´ªª´— ‹µ„œ´Êœ‹´—Á˜¦¸¥¤Á‡¦ºÉ°Š¤º°ª´—¦´ Š¸Â„¤¤µ Ážd—
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°Š˜´ª°¥nµŠ—·œ ‹Îµœªœ 69 ˜´ª°¥nµŠ ץčo®´ ªª´—¦´ Š¸ÂÁ‹°¦r¤µÁœ¸¥¤¦· »š›·Í(HPGe) ¨³¦³ª·Á‡¦µ³®rÂ„¤
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2. „µ¦ª·Á‡¦µ³®r¡¸ ‡¡¨´ ŠŠµœ (photo peak) ‹µ„Áž„˜¦´¤¡¨´ ŠŠµœ °Š¦´Š¸Â„¤¤µ‹³Äo ަ„¦¤
‡°¤¡·ªÁ˜°¦r εÁ¦È ‹¦¼ž (Genie 2000) Ĝ„µ¦ª·Á‡¦µ³®r Áž„˜¦´¤¡¨´ŠŠµœ °Š¦´Š¸Â„¤¤µÂ¨³‡Îµœª–‡n µ„´¤¤´œ˜£µ¡
‹ÎµÁ¡µ³ °Š 40K 226 Ra 232 Th ¨³ 137 Cs Ĝ˜´ª°¥n µŠ—·œš´ÊŠ 69 ˜´ª°¥nµŠ š¸ÉÁ„ȝ‹µ„ 6 °ÎµÁ£° šµŠ˜°œœ °Š‹´Š®ª´ —
¡´ š¨»Š ×¥¤¸®¨´ „Äœ„µ¦ª·Á‡¦µ³®r ‡º° „µ¦ª·Á‡¦µ³®r 40K ‹³ÄoâØ¡¸‡š¸É¡¨´ ŠŠµœ 1460.8 keV ‹µ„ÁoœÁž„˜¦´¤
¡¨´ŠŠµœ °Š˜´ªÁ°Š 宦´  226 Ra ‹³ÄoâØ¡¸ ‡š¸É¡¨´ŠŠµœ 351.9 keV ‹µ„ÁoœÁž„˜¦´¤¡¨´ŠŠµœ °Š 214 Pb nªœ
232 Th ‹³ÄoâØ¡¸‡š¸É¡¨´ŠŠµœ 583.2 keV ‹µ„ÁoœÁž„˜¦´¤¡¨´ŠŠµœ °Š 208Tl ¨³ 137 Cs ‹³ÄoâØ¡¸ ‡š¸É¡¨´ŠŠµœ
661.7 keV ‹µ„ÁoœÁž„˜¦´¤¡¨´ŠŠµœ °Š˜´ªÁ°Š š´ÊŠœ¸Ê ŗo ‡Îµœª–°´˜¦µž¦·¤µ–¦´Š¸—¼—„¨ºœÄœ°µ„µ« (absorbed dose
rates in air ; D) „´¤¤´œ˜£µ¡¤¤¼¨Á¦Á—¸¥¤ (radium equivalent activity ; Raeq ) —´œ¸‡ªµ¤Á¸É¥Š °Š¦´Š¸£µ¥œ°„
(external hazard index ; H ex) °Š˜´ª°¥nµŠ—·œ – ¦·Áª–˜nµŠ ÇĜ‹´Š®ª´—¡´š¨»Š ×¥œÎ µ o°¤¼¨‡nµ„´¤¤´œ˜£µ¡‹ÎµÁ¡µ³
°Šœ·ªÅ‡¨—r 40K 226Ra ¨³ 232 Th ¤µÄoĜ„µ¦‡Î µœª– —´Š¤„µ¦˜n °Åžœ¸Ê
Th Ra K C604 .0+C462 .0+C 0417 .0=)h/ nGy (D …..………………………(1)
Th Ra K eq C43.1+C+C077 .0= Ra……..…..……..……………………….(2)