Intratrack Processes Research Articles

Simulation of DSB yield for high LET radiation.

A simulation approach for the calculation of the LET-dependent yield of double-strand breaks (DSB) is presented. The model considers DSB formed as two close-lying single-strand breaks (SSB), whose formation is mediated by both intra-track processes (single electrons) or at local doses larger than about 1000 Gy in particle tracks also by electron inter-track processes (two independent electron tracks). A Monte Carlo algorithm and an analytical formula for the DSB yield are presented. The approach predicts that the DSB yield is enhanced after charged particle irradiation of high LET compared with X-ray or gamma radiation. It is used as an inherent part of the local effect model, which is applied to estimate the relative biological effectiveness of high LET radiation.

Resemblance of intratrack processes as a common starting point of radiation chemistry and positron, muon, and Mössbauer spectroscopies

A comparison of the yields of final products (57Fe2+, 119Sn2+) of the transformation of Mossbauer nuclei (57Co, 119Sn) in frozen aqueous and alcoholic glassy solutions with the Ps, Ms, and radiolytic-hydrogen formation probabilities in the same liquid media subjected to irradiation with positrons, muons, and fast electrons, respectively shows that the yields of 57Fe2+, 119Sn2+, Ps, Mu, and H2 vary in similar manners with a change in the concentration of electron scavengers or the temperature of the medium. These correlations are a manifestation of a profound similarity between the primary processes occurring in ionizing-particle tracks. Obviously, the recombination of ion-electron pairs inside large swarms (blobs) involving H2O+, e+, μ+, Fe3+, and 119Sn3+, respectively, is the most important process for understanding the formation of H2, Ps, Mu, 57Fe2+, and 119Sn2+.

Positronium formation in a liquid phase: Influence of intratrack reactions and temperature

AbstractThis work clarifies some discrepancies between conventional models, used in positron annihilation lifetime (PAL) spectroscopy, and experimental data. The importance of taking into account Ps interactions with primary intratrack radiolytic products is demonstrated, for example, for PAL data in water. We examine the applicability of a nonhomogeneous chemical kinetics approach and of a well‐known expression for the reaction rate constants to describe intratrack processes, and show that the prescribed diffusion approximation (PDA) is a reasonable model for this. Moreover, we have derived an analytical expression for the time‐dependent reaction rate coefficient, which previously entered PDA as an external parameter. Preliminary fittings of the PAL spectra in H2O over a wide temperature range indicate that Ps reactions in intratrack processes are diffusion controlled (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Influence of Temperature on Intratrack Processes and Ps Formation and Behaviour in Liquid Water

Positron annihilation lifetime (PAL) spectra are measured in liquid water in the temperature range 2 – 930C. The spectra are treated by taking into account intratrack reactions and assuming that radical reactions with Ps are diffusion-controlled (the respective temperature dependences obeying the Stokes-Einstein law). Equilibrium Ps bubble parameters are obtained.

To the theory of Ps formation. New interpretation of the [formula omitted] lifetime spectrum in water

A brief review of ideas behind the blob model is given. For the first time positron annihilation lifetime spectrum in liquid water is deconvoluted without a usage of the multi-exponential approach, but on the bases of the blob model, which suits well for description of the intratrack processes including positronium (Ps) formation in condensed molecular media. All adjustable parameters in the blob model have clear physical meaning. Excellent agreement with the experiment is obtained.

A model for radiolysis of nitric acid and its application to the radiation chemistry of uranium ion in nitric acid medium

Primary yields of radiolysis products of water and nitrate in concentrated nitric acid solutions for low LET radiation were evaluated from the previous studies on radiolysis while those for high LET radiation by using a diffusion kinetics model for the intra-track processes. Radiolytic reactions of NO x and uranium ions in the solutions were proposed mainly from the reported data, and then applied together with the yields to the radiolytic formation of HNO 2 and oxidation of U 4+ to demonstrate the reaction model.