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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 - 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. |