High Dose Measurements of Some Materials Exposed to Gamma Radiation and its Applications

Abstract

The main objective of this work is to study the dosimetric characteristics of some new kinds of materials represented as films, liquid and gel form to measure the absorbed radiation at low and high dose . Unit (1) Compare the results obtained from a new dosimeter/label film using Resazurin pH indicator dye dying a poly vinyl alcohol with the results obtained from FWT film which is considered one of the most famous dosimeters used as a routine dosimeter in a lot of commercial process all over the world , proved the closeness of both results (FWT 1% ,2.5% Resazurine) from the results obtained by Fricke dosimeter (reference dosimeter). Also, the films have excellent stability before and after irradiation , and possible using as a lable in low and moderate dose range . The combined uncertainty at 2 σ was found to be 5.2 % . The film is so cheep in comparison with imported FWT films . Unit (2) Two previously studied dyes (m-cresol and tetrabromo phenol phathalein ethyl ester wereexamined, individually proved suitability of each dye in assess the absorbed dose at low dose application . So gathering the two pH indicator dyes in the same polymer matrix (poly vinyl alcohol ) extend the dose range up to 60 kGy for serving low and high dose application . The films are highly stable for long times in dark and are not affected by relative humidity changes in the range of (10% -60% ). The combined uncertainity at 2 σ was found to be 6.33%.

. Unit (3) Aqueous solution of pH indicator tetrabromo phenol phathalein ethyl ester (TBPE) containing chloral hydrate was used as a liquid dosimeter in the range 0.5-2 kGy depending on the concentration of both dye and chloral hydrate.In the current work a new approach was used through back titration of acid-sensitive dye (TBPE) with irradiated chloral hydrate, extend the applicable dose range to 5 kGy. So, if avoid exposure of dye to direct gamma irradiation and proceed back titration with irradiated chloral hydrate leads to double extend the dose range available in comparison with direct way of irradiation . Unit (4) Brilliant Greendye wasprepared in gel form for low dose application was studied , these gels matrix are highly stable for long time before and after irradiation under different storage condition . BG-gelatin gels are suitable in the dose range from 200—1800 Gy . A comparison study between different forms of Brilliant Green dye in shape of films and gel was done . From this comparison one can easily choose the suitable dosimeter need to cover the target applications . . Unit (5) Electron paramagnetic resonance technique was used to evaluate the dosimetric properties of Carrgeenan rods. Carrageenan rods is a suitable dosimeter in a dose range of 0-130 kGy . The dosimetric characteristic of rods containing different concentrations of Carrageenan were recorded. The rods have significant EPR signal which develops upon irradiation . Intensity of the signal increases upon increase the irradiation dose. These rods have insignificant dependence on relative humidity changes during irradiation. The properties of the prepared Carrageenan rods suggest theiruseful application for food irradiation in the dose range from 0-30 kGy, and for higher dose applications such as health care, sterilization of medical device and some polymer modifications . These dosimeters have excellent stability before and after irradiation.