Section:-Physical Science Study of Natural Radioactivity in some Rock and Soil Samples. Abdu Hamoud Al-Khawlany*1, P. P. Pawar1, J. M. Pathan2 1 Department of physics, Dr. Babasaheb Ambedkar Marathwada University Aurangababd 431001, India. 2 Department of physics, Maulana Azad college Aurangabad (M.S)431001, India. * Corresponding Author: abdu.alkhawlany@gmail.com,pravinapawar4@gmail.com. Key Words: Gamma Ray, Multichannel analyzer, Natural Radioactivity, Activity Concentration. Abstract: The natural radioactivity of K40, Th232and Ra226 in rocks and soils samples collected around Aurangabad-Maharashtra in India. The concentration of radionuclide in samples were determined by gamma-ray spectrometer NaI(Tl) detector. The aim of the present work is to measure the levels of natural radioactivity in the selected samples. In addition to this radiological hazard assessment due to natural radionuclide carried out and the average activity concentration of 226Ra, 232Th, 40K were determined. The Radium equivalent, air absorbed gamma radiation dose rate and external radiation hazard index and the annual effective radiation dose were calculated in this study. Introduction: Measurements and studies of natural radioactivity in rock and soil are very important to determine the amount of change of the natural background activity with time as result of any radioactive release, monitoring of any release of radioactivity to the environments is important for environmental protection. Naturally, radioactivity arises from the primordial radionuclide, such as K40 and radionuclide from U238 and Th232 series and their decay products. Uranium and Thorium occur at trace levels in the earth crust and 0.018% of the total amount is potassium K40 [1].The activity concentrations of radionuclides were measured using scintillation detector. Gamma radiation emitted from naturally from naturally occurring radioisotopes such as K40 and radionuclides from the Th232 and U238 series, which exists at trace levels in all ground formation, represents the main external sources of radiation to human body. -1- Human beings are exposed to radiation from source outside their body's mainly cosmic rays and gamma rays emitters in soils, rocks, water, food air and building materials. Therefore, the assessment of gamma radiation dose from natural source is of particular importance as natural radiation is the largest contributor to the external dose of the world population [2]. The radioactivity due to natural radionuclide in rocks and soils generate a significant component of the background radiation exposure to the population. The terrestrial component of natural background is dependent on the compositions the rocks, soils and water[3,4]. Experimental : Sampling and Sample-Preparation: Rocks and soils sample were collected from selected locations Aurangabad Maharashtra India. Rock sample were crushed to small pieces and grinded to powder. Soil samples were collected with field boundary a road, a tree or other obstruction. Fig. 1 Four sites selected for sample collection. The location of the four sites selected for study is shown in table – 1 in the form or longitude and latitude.Table -1 Longitude and Latitude of the sample sites . Spot Sample No Location Harsul 1 Tank 2 Ohar 3 Jatwada Tanda 4 Turn Latitude Longitude 19.926436 75.329620 19.946103 75.313918 19.956592 75.285846 19.966837 75.273615 Soil sample taken from different places were cleared area from the ground surface up to 2 cm. Each sample (rock/soil) were dried in oven at (105 C) and sieved through 18 meshes which is optimum size. -2- The activity concentrations of soil/rock samples were calculated by this formula. A  CPs E  I W A: Activity concentration of the samples (Bq/Kg) Cps: The net count per second = CPS for sample-cps for background value. E: The counting efficiency of the gamma-energy. I: Absolute intensity of gamma-ray [5]. W: Net weight of sample (in kilogram (kg) or liter (L)) Radium Equivalent Activity: Raeq (Bq/Kg) = ARa + 1.43 ATh + 0.077 Ak Where ARa , ATh , Ak are the specific activities of Ra226, Th232 and K40 in (Bq/K) External Hazard Index: Hex  ARa A A  Th  K  1 370 259 4810 Where ARa , ATh , Ak are specific activities of Ra226, Th232 and K40in (Bq/Kg) .The value of Hex must be lower than unity in order to keep the radiation hazard insignificant (Safe). Internal Hazard Index: Hin  ARa ATh A   K 1 185 259 4810 Where ARa , ATh , Ak are specific activity concentration of Ra226, Th232 and K40.Each sample will be measured with gamma-ray spectrometer consisting of NaI (Tl) setup and multi channel analyzer (8192) channel, with following specification. Resolution (FWHM) at 1.33Mev C060 is 60 kev, relative efficiency is 7.5%. Radiation Hazard Index (Level Index Iγ): I  ARa A A  Th  K  1 150 100 1500 Where ARa , ATh , Ak are same meaning. -3- Absorbed Dose Rates: D(nGr.h-1) = 0.462 ARa + 0.604 ATh+ 0.042 Ak Where ARa , ATh , Ak are specific activities of Ra226, Th232 and K40 (Bq/Kg) Outdoor Annual Effective Dose: E (mSv/year) = D x 24 x 365 x 0.2 x 0.7 x 10-6 D : absorbed dose rate of gamma-ray. Results and Discussion : Natural radioactivity is present in soil and rocks may be changed by anthropogenic activities (like the use of fertilizers). The mean activity concentration in soil for Ra226, Th232 and K40 are agree with worldwide average and the world average concentration are 35, 30 and 400 Bq/kg for Ra226, Th232 and K40. The result showed that psammitic rocks are rich in K40.The activity concentration in sandy soil are higher than activity for clay soil. (Saleh Elmageed -2013). The mean value of Raeq is less than the threshold value of 370 Bq/Kg the mean annual effective radiation dose is less than the dose rate reported worldwide. In general the activity concentration of radionuclide in the different types of samples are variable and do not shown any particular pattern. Conclusion : The activity concentration of the naturally occurring radionuclide of Ra226, Th232 and K40 in soil/rock samples were determined by gamma spectrometry. Measured mean activities are less than the world average values and the values of external radiation doses are less than the world average value. The value of mean absorbed dose rate, outdoor annual effective dose and radium equivalent activity are lower than global average values whereas the external hazard indices are less than unity which indicated that there are no probability of immediate health effect on workers and public due to natural radioactivity present in the samples [5]. 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