Naslov
PULSED EPR STUDY OF LOW DOSE IRRADIATION EFFECTS FOR L-ALANINE CRYSTAL IRRADIATED WITH GAMMA -RAYS, Si AND Ne ION BEAMS

Autori
Rakvin, Boris ; Maltar-Strmečki, Nadica ; Nakagawa, Kouichi

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
6th European Federation of EPR Groups Meeting-Programme and Book of Abstracts / - , 2006

Skup
6th European Federation of EPR Groups Meeting

Mjesto i datum
Madrid, Španjolska, 05.09.2006. - 08.09.2006

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Pulsed EPR; L-alanine

Sažetak
L-alanine has been the most common substance in electron paramagnetic resonance (EPR) dosimetry studied for the last 20 years [1]. EPR signal of irradiated sample shows a linear dependence on the absorbed dose in relatively broad dose range from 0.5 Gy to 105 Gy, with long-term stability of the dosimetric signal. Besides the most often application related to γ -irradiation there are also considerable intentions to extend alanine dosimetry to high linear energy transfer (LET) ions radiation. The effects of small doses, especially in the therapy level range (0.5 - 100 Gy) for both types of irradiations are important to more detail understand microscopic local concentration and distribution of these centers. One expects to obtain such information through the studies of spectral intensities and relaxation times of paramagnetic centers by employing CW EPR and Pulsed electron spin echo (ESE) techniques. However, in the limit of small irradiation dose the signal intensity is reduced and only CW EPR was frequently used while a Pulsed ESE was eliminated from such investigations due to even smaller signal to noise ratio compared to CW EPR. The additional unfavourable condition to employ Pulsed ESE technique is related to strong spectral diffusion, which is present in alanine spectrum and it produces difficulties to extrapolate relevant relaxation parameters. In this work we present Pulsed ESE spectra of irradiated alanine crystal by γ -ray and (Ne and Si) ions detected in the limit of small doses (110 Gy and 200 Gy). The kinetic of an ESE signal decay of γ -irradiated alanine crystal, which exhibits complex relaxation behavior was analysed in terms of instantaneous and spectral diffusion and spin flip-flop rate at room temperature [2]. The local concentration of paramagnetic centers, C (Ne ions, LET 68 keV/&micro ; ; m, 110 Gy, )/C (γ -ray, 200 Gy) = 62, and C (Si ions, LET 75 keV/&micro ; ; m, 200 Gy, )/C (γ -ray, 200 Gy) = 34, at the low dose for ions radiation was deduced from corresponding spin-spin interaction.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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