Estimation of cosmic dose rate using passive dosimeter and soil radioactivity

The terrestrial gamma rays are essentially derived from 40K and radionuclides belonging to and 238U and 232Th series that are present in the earth's crust. The worldwide average value for outdoor gamma absorbed dose rate in air due to terrestrial sources is 54 nGy h-1 and the relative contributions of 40K, 238U, and 232Th to this dose are about 35%, 25% and 40%, respectively. For Indian environs these percentage contributions is in the order of 17.7%, 33.6%, and 48.7% due to 238U, 232Th, and 40K, respectively. The variation of terrestrial radiation is typically larger than that of cosmic rays. There are regions in the world where the outdoor terrestrial radiation exceeds substantially the average value due to the enrichment of certain radioactive minerals leading to the formation of what are known as high background areas. The presence of high background areas has been reported in several countries like China, Iran, Germany, USA, Brazil, and India. The primary objective of this paper is to estimate the cosmic ray dose rate at Kakrapar, Gujarat using Thermoluminescence (TL) data and soil radioactivity data