الفهرس 
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Abstract
I’
Radiation received by human is of either natural or artificial origin. Before the
discovery of artificial production of radiation, natural sources were the only sources of
exposure. Today, natural sources still contribute almost 80 percent of the collective
radiation exposure ofthe world’s population, so they contribute more significantly than
does artificial radiation to collective exposure dose. By living andlor working either in”
the open or inside buildings, human beings are exposed to radiation from sources
outside their bodies. The radiation is mainly from cosmic rays and radionuclides in the
ground and walls buildings. Also, by ingesting food and water, and inhaling air.
In the present study natural radioactivity in soil, fertilizer, foodstuffs,
ground water and crude oil has been determined using gamma spectrometry. In order to
achieve this work, the thesis is composed of seven chapters.
Chapter one is an introduction and previous studies in the field of measurements
of environmental radiation in soil, foodstuffs, fertilizer, groundwater and crude oil. The
chapter also contains the aim of the present work.
Chapter two represents a theoretical background concerning radioactivity from
natural and man made sources. Also, the chapter deals with radioactivity in soil,
foodstuffs, fertilizer, groundwater, and crude oil and dose assessment.
Chapter three contains methods of sample collection and prepar?-tio~. It includes
detailed description of experimental work, detection of radioactivity and calibration of
the detector (HPGe).
Chapter four includes the results and discussion of obtained results for soil and
fertilizer and its comparison with pervious data. The main results are given in the
following:
The average concentrations of 226Ra, 232Th, 40K and 137 Cs in soil samples were
16.43, 18.3,268.18,3.25 Bq kg” respectively.
The dose rate conversion factors (DRCFs) were calculated in this work to
deduce the gamma ray absorbed dose rate at 1 meter above ground surface in stead
of using the published values. The obtained values ofthese factors are compared
with other published values and were found to be in good agreement.