الفهرس 
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Abstract
The main purpose of this work is to study the preparation and the
possibility of use dyed films for dose monitoring in radiation processing
application. Additionally, it aims to preparation of lithium borate glass by
melt-quenching technique with different additive for possible as
dosimeter with application in both low and high doses. Finally, it aims to
use DL- -aminopimelic acid in powder form as EPR dosimeter and to
study their dosimetric characteristics for wide dose range application. The
results obtained in this work can be summarized as following:
Part (1):
Deals with the investigation of gamma radiation effect on dyed
polymeric film (mixed dye film and radiation sensitive indicator) for
possible application in food irradiation. This part is divided into two
sections:
Section (1):
The polymer films under investigation include poly (vinyl alcohol)
in a combination with mixture of two dyes, namely, 2,6-dichlorophenol
indophenol sodium salt (DCP), and tetrabromophenol blue (TBPB) as
pH indicator in presence of various chloral hydrate concentrations. These
films undergo color change from the blue to the yellow color passing
through green as an intermediate color. The decoloration reaction of DCP
started first in the beginning of reaction, followed by the transformation
of TBPB to its acidic form as a result of the delivery of HCl from the
radiolysis of chloral hydrate. The dosimetric parameters, eg; dose
response, effect of relative humidity on response as well as pre- and postirradiation
stability of these films were inspected. The energy band gap
value of the prepared films decreased from 1.83 to 1.75 as a result of
increasing the absorbed dose. These films can be used as dosimeters for
food irradiation applications where the useful dose range is recorded from
1 to 15 kGy.
Section (2):
Poly vinyl alcohol films dyed with metanil yellow (MY) indicator
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irradiation the films undergo visual color change from yellow to red due
to releasing of HCl. Acid-formed concentration is enhanced with the
addition of chloral hydrate. The G-(value) of formed acid concenrtation
was estimated. The prepared films were examined to be an applicable
dosimeter in dose range from 0.5 to 12 kGy. The effect of relative
humidity was determined, as well as pre and post irradiation stability.
Part (2):
Describes the preparation of four glass systems based on lithium
borate. The first glass is lithium borate, the second is lithium borate
doped with CuO, while the third is lithium borate doped with CuO
incorporated with TeO2 as a modifier; The last one is lithium borate with
TeO2. All the previous glass systems were prepared by melt-quenching
technique. UV-VIS Spectrophotometer was used to evaluate the change
in the optical properties before and after irradiation. Gamma irradiation
causes profound changes in the peak intensity which is due to the
breaking of the network bonding. For the first glass system the sensitivity
to gamma radiation is low and Eg value was estimated, the second glass
system exhibits a decrease of optical energy gap value from 3.5 to 2.59
with the dose range from 1 to 25kGy. For the third glass system, the
addition of TeO2 effects on the value of Eg where it acts as a modifier and
Eg decreased from 3.1 to 2.4 ev, which is attributed to the increase of non3
bridging oxygen (NBO) and the increase of defect in the glass, also the
sensitivity of glass increased and can be used as a dosimeter in wide dose
range from 100Gy to 45kGy. Finally, the last glass system doped with
TeO2 can be used as dosimeter from 50 Gy to 3kGy and the value of Eg
decreased from 3.47 to 3.15. The effect of gamma radiation on electrical
conductivity was studied. All types of transition are direct allowed
transition, and also the stability was followed up before and after
radiation.
Part (3):
Discuss the developing of polymeric film for high dose radiation
dosimetry application. These films are based on Poly (vinyl butyral copoly
vinyl alcohol co-vinyl acetate) (PVB-co-PVA/PVAC) combined
with 4-(p-nitrophenyl-azo)-1-naphthol dye has been examined to be a
promised dosimeter suitable for high dose ranges. The prepared films
have yellow color. This color undergoes color bleaching upon irradiation
with gamma rays. Different concentrations were prepared to obtain the
suitable dosimeter in the dose range from 3 to 200kGy depending on the
dye concentration. Chloral hydrate was added in different concentrations,
as a result the bleaching reaction expedites and in accordance the dose
range diminishes to be 35kGy. The effect of chloral hydrate as well as
dye concentration on response curve was studied. The radiation efficiency
(G-value) was estimated for the prepared films. The influence of relative
humidity during irradiation was estimated as well as stability before and
after irradiation.
Part (4):
EPR solid state dosimeters have wide-spread applications in
radiation processing. One of the goals of the present study is to
investigate the EPR dosimetric characteristics of DL- -aminopimelic acid
powder for high dose range from 2 to 160kGy. The EPR spectra of
unirradiated DL- -aminopimelic acid powder exhibit no EPR signal even
at high microwave power and modulation amplitude. However, upon
irradiation upon irradiation the spectrum exhibits an EPR signal with
sextet signal. The EPR signal has unique spectroscopic splitting factors of
g1= 2.032, g2=2.02167, g3=2.01364, g4=2.00647, g5= 1.99916 and
g6=1.99013. The EPR spectrometer parameters such as microwave power
and modulation amplitude were studied to choose the suitable parameters
for dosimetry evaluation. The number of free radical formed per 100 ev
(G-value) found to be 0.201. The powder has an excellent Storage
stability before and after irradiation and can be used in food and medical
irradiation application processing.