| Autor: |
Souici M; Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement , 16 Route de Gray, 25030 Besançon Cedex, France.; Laboratoire de Physique des Rayonnements et Applications, Université de Jijel , BP 98, Ouled Aissa, Jijel 18000, Algérie., Khalil TT; Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement , 16 Route de Gray, 25030 Besançon Cedex, France., Muller D; Laboratoire ICube, CNRS-Université de Strasbourg , 23 rue du Loess, 67037 Strasbourg, France., Raffy Q; Institut Pluridisciplinaire Hubert Curien, UMR CNRS 7178 , 23 rue du Loess, BP 28, 67037 Strasbourg Cedex 2, France., Barillon R; Institut Pluridisciplinaire Hubert Curien, UMR CNRS 7178 , 23 rue du Loess, BP 28, 67037 Strasbourg Cedex 2, France., Belafrites A; Laboratoire de Physique des Rayonnements et Applications, Université de Jijel , BP 98, Ouled Aissa, Jijel 18000, Algérie., Champion C; Université de Bordeaux, CNRS/IN2P3, Centre d'Etudes Nucléaires de Bordeaux Gradignan, CENBG , Chemin du Solarium, BP 120, 33175 Gradignan, France., Fromm M; Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement , 16 Route de Gray, 25030 Besançon Cedex, France. |
| Abstrakt: |
Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90-3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a maximum in the 150-200 keV energy range; as for LET, it peaks at 90 keV. We also show that fragmentation starts to be significant for proton fluences greater than 1 × 10 11 cm -2 at the Bragg-peak energies. Finally, we determine the average proton track radial extension, r max , corresponding to an occupation probability of 100% DSB in the Bragg-peak region. The r max values determined are in excellent agreement with the radial extensions of proton tracks determined by simulation approaches in water. When plotted as a function of LET, both SSB and DSB cross sections bend back at high LETs. |
