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The radioactivity of the dissected earth formations of Tar Al-Najaf in Al-Najaf Al-Ashraf Governorate has been studied, which is considered one of the most important archaeological areas in the province, as Tar Al-Najaf is one of the natural phenomena prominently present in the governorate; it cuts sharply to form a rocky cliff, as well as overlooks from the southern end of a plateau Al-Najaf and on the sea of Al-Najaf, in a clear and surprising way, Al-Najaf flew, by selecting 50 sites to take samples from the region. Spectral measurements were made using a thallium-activated sodium iodide detector (Nal (TI) (3 "× 3")). It was found that the specific activity of (_^238)U, (_^232)Th and (_^40)K in the studied ranged between (27.644 ± 1.505) Bq.kg^(-1) to (6.530±0.509)Bq.kg^(-1) with average (15.955)Bq.kg^(-1), (31.06±1.73)Bq.kg-1 to (8.356±1.013)Bq.kg^(-1) with average (21.728) Bq.kg^(-1)and (475.391 ± 7.870) Bq.kg^(-1)to (95.173 ± 1.994) Bq.kg^(-1) with average (281.197) Bq.kg^(-1)respectively. The value of Absorbed Dose Rate in Air was also calculated, it was between (47.389) (nGy/h) to (16.366) (nGy/h) with average (34.950), the Annual Effective Dose in door between (0.234) (mSv/y) to (0.080) (mSv/y) with average (0.171), the Annual Effective Dose out door between (0.058) (mSv/y) to (0.020) (mSv/y) with average (0.0423),the excess lifetime cancer risk (in) between (0.0423) to (0.280) , with average ( 0.599), and the Excess lifetime cancer risk (out) between (0.205) to ( 0.070), with average (0.149). Comparing the present results with the globally considered values, it was found that the radiation levels of the studied samples are within the permissible limits. Keywards: Natural radioactivity, gamma spectrum, Nal(TI) detector , Tar Al-Najaf area . |
