ESR Dosimetric Study on Gamma Induced Radicals in DL-Ornithine Hydrochloride

Sayeda Eid

doi:10.4236/ojpchem.2013.31005

Abstract

DL-ornithine hydrochloride rods (3 ×10 mm) were studied to be a radiation sensitive material for EPR dosimetry. The rods have specified EPR signal developed under irradiation and its intensity increases with the increase in absorbed dose. The intensity also affected by the concentration of DL-ornithine in the rods. The prepared rods can be used in the dose range from 0.5 - 50 kGy. The obtained number of free radicals per 100 eV (G value) was found to be 0.3551 ± 0.0333. The hyperfine (hf) coupling constant is 2.325 mT at g-factor 2.033. The rods have the advantage of negligible humidity effects during irradiation. The pre and post- irradiation stability was found to be satisfactory.

Highlights

Electron spin resonance (ESR) has been successfully applied to measuring intermediate and high doses using alanine as a radiation-sensitive material [1,2,3].One of the advantages of ESR dosimetry is that the read out does not affect the spin concentration; the sample can be evaluated many times
The rods have specified Electron paramagnetic resonance (EPR) signal developed under irradiation and its intensity increases with the increase in absorbed dose
Polycrystalline phenyl-alanine and perdeuterated L-αalanine were studied as potential high-energy radiationsensitive materials (RSM) for solid state/EPR dosimetry [5]

Summary

Introduction

Electron spin resonance (ESR) has been successfully applied to measuring intermediate and high doses using alanine as a radiation-sensitive material [1,2,3].One of the advantages of ESR dosimetry is that the read out does not affect the spin concentration; the sample can be evaluated many times. Electron spin resonance (ESR) has been successfully applied to measuring intermediate and high doses using alanine as a radiation-sensitive material [1,2,3]. Electron paramagnetic resonance (EPR) was proposed as a method to measure radiation-induced radicals. The dose response influence of humidity and temperature during irradiation, energy dependence as well as storage at different conditions are discussed [8]. A number of solid materials, including amino acids, in which free-radical populations are formed by irradiation, have been suggested for highdose dosimetry by Electron Paramagnetic Resonance (EPR) analysis. A useful method of high dose measurement is the use of EPR spectrometry of irradiated amino acids, in particular L-alanine, CH3CH(NH2)COOH, purified in polycrystalline form [9,10,11,12]. Several improvements to reduce the orientation effects can be accomplished by certain time-consuming procedures, e.g. for pellet-shaped dosimeters, averaging the measured values at two different orientations 90 ̊ apart [14,15] or by using double-integration of the spectrum [16], and for film dosimeters, by attaining maximum amplitude or by averaging the maximum and minimum amplitudes [17]

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