科研之友
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摘要
Alpha radiations in the ground arises from the decay of naturally occurring uranium and thorium, which are widely distributed in soils and rocks. According to Environmental Protection Agency (EPA) reports, the highest of alpha activity is found in locations near copper mines. In this study, the amounts of natural activity of alpha emitters for 31 samples of surface soil of Talmesi Anarak mine, located in center of Iran, are measured by Nuclear Track method. Having virtually zero background and exposure time, are advantages of this method. After sampling, all of the 31 samples were transferred to laboratory to place CR-39 detectors vertically in them. In next step, CR-39 detectors were etched in NaOH 6 M, aqueous solution at 70 degrees C for 4 h. Then, number of tracks per area unit was counted by an optical microscope. The amounts of alpha activity were calculated in all samples and range of minimum 1.40E + 04 to maximum 3.03E + 05 Bq/kg. And also the activity of Th-232 and U-238 are measured by alpha-track method. Moreover %26quot;equivalent uranium%26quot; (eU) and %26quot;equivalent thorium%26quot; (eTh) by Hp-Ge detector, were calculated.
- 出版日期2013-3
