الفهرس 
ABSTRACT
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Abstract
The studies of natural radioactivity are mainly concerned with three issues. The first is to investigate the origins and distributions of
radionuclides on the earth’s surface. Naturally occurring
radionuclides, such as 40K, as well as radionuclides from the 238U and
232Th series and their decay products exist at trace levels in all ground
formations. The Second is the natural radionuclides are considered as
external sources of radiation to the human body. The external
exposure of most of these radionuclides is caused by gamma
radiation and depends on the geological and geographical conditions
(UNSCEAR, 2000). Finally, the study makes it possible to obtain the
background baseline of naturally occurring radionuclides for
investigating the environmental impact of anthropogenic radioactive
sources.This study is a continuation of our ongoing scientific
cooperation between physics department - faculty of science, Al-
Azhar university, Assiut branch, Egypt and physics department -
faculty of science, Assiut university, Egypt, related to the
measurement of specific activity of 226Ra, 232Th and 40K in
environmental samples from Assiut governorate using a gamma-ray
spectrometric technique and estimation of the gamma dose rate from
these radionuclides.This study concerned with measurement of naturally
occurring radionuclide 226Ra, 232Th and 40K in soil samples .Ninety
three soil samples have been collected. We classified it as follow:ighteen samples collected from area surrounding the fertilizer plant
in Assiut, fifty three cultivated soil samples and twenty two
reclaimed soil samples collected from three regions in Assiut
governorate to assess the doses received by population in Assiut
governorate.
The work was performed by using gamma ray spectrometer
(sodium iodide NaI (Tl) detector) in radiation physics lab. At the
Physics Department, Faculty of Sciences, Al-Azhar University,
Assiut, Egypt. The detector is connected the following components:
Preamplifier, main amplifier, analogue to digital convert and
Canberra Multichannel Analyzer (MCA), with Genie 2000 software.The specific activity concentrations in surface soil samples
collected from area surrounding the fertilizer plant, Assiut, ranged
from 30±1.5 to 77±3.9 Bqkg-1 with an average value of 50 Bqkg-1 for
226Ra. while in case of 232Th its values are ranged from 25±2.5 to
63±3.2 Bqkg-1 with an average value of 44 Bqkg-1. Finally for 40K the
values ranged from 108±5.40 to 346±17.3 Bqkg-1 with an average
value of 211 Bqkg-1. In other hand the activity concentrations for
226Ra, 232Th and40K in deep soil samples taken at depth 30 cm
collected from area surrounding the fertilizer plant, Assiut, ranged
from 102±3 to 194±10 Bqkg-1 with an average value of 139 Bqkg-1,
119±6 to 187±9 Bqkg-1 with an average value of 147 Bqkg-1 and 259±13 to 464±23 Bqkg-1 with an average value of 291 Bqkg-1 respectively.