Radial electron fluence around ion tracks as a new physical parameter for the detection threshold of PADC using Geant4-DNA toolkit

Abstract

The detection threshold of poly(allyl dyglycol carbonate), PADC, for C ions is determined as 55 eV/nm in stopping power, which is significantly higher than that for proton and He ions. The stopping power is not a universal parameter for expressing the detection threshold of PADC. A new physical parameter of Radial Electron Fluence around Ion Tracks, REFIT, is proposed to describe the detection threshold of PADC. It is defined as the number density of electrons passing through the surface of a cylinder of a certain radius that is co-axial with the trajectory. Furthermore, preliminary calculations are presently being performed using the Monte Carlo simulation code of Geant4-DNA. The values of the REFIT at the detection thresholds for each ion are of the same order. Several issues affecting implementation of the REFIT paramter are discussed. These include the effects of impact parameter relating to the initial locations of secondary electrons, the effects of electron attachment below the cut off energy of 7.4 eV and the necessity of a more physically realistic medium than water for Monte Carlo simultaions.

Distinct step-like changes in G values for the losses of typical functional groups in poly(ethylene terephthalate) along boron ion tracks around the detection threshold

“…Effects of low energy electrons around ion track have never examined well (Fromm et al, 2015). In order to evaluate structure of secondary elections, we have started a simulation using a Monte Caro Code of Geant4-DNA tool kits (Kusumoto et al, 2017). , the reduced etch rate ratio, , was evaluated using the following formula (Somogyi, 1980;Yamauchi et al, 1992), .…”

Quantitative estimation of track segment yields of water radiolysis species under heavy ions around Bragg peak energies using Geant4-DNA

“…Indeed, the description of the dependence of G-value is improved compared to that with LET, but Z eff /β has not been recognized as a universal parameter. To universally express G-values of water radiolysis products in a wide LET range, the electron interaction concept, which the number of interaction induced by secondary electrons governs the radiation induced yields could work well 7 , 44 , 45 . Furthermore, G-values of · OH for Fe ions by the present simulation are significantly lower than the experimental results.…”

Methodological and Conceptual Progresses in Studies on the Latent Tracks in PADC

“…Two PhD studies have been performed and their progresses are the body of the present contribution [ 12 , 13 ]. For the two research projects, the Fourier transform infrared (FT-IR) spectrometry has been the main experimental method.…”

“…In its present state, the simulation is able to reproduce dose distribution comparable to the Katz model in water. From these simulations, new physical parameters have been proposed by Kusumoto et al to describe the response of PADC detector [ 39 , 40 ]. Radial Electron Fluence around Ion Tracks, REFIT , has been defined as the number density of secondary electron passing through the cylinder with identical track-axis as the ion-pass [ 39 ].…”

“…From these simulations, new physical parameters have been proposed by Kusumoto et al to describe the response of PADC detector [ 39 , 40 ]. Radial Electron Fluence around Ion Tracks, REFIT , has been defined as the number density of secondary electron passing through the cylinder with identical track-axis as the ion-pass [ 39 ]. The Number of Interactions by Secondary Electron, NISE , has in turn been defined as the number of interactions counted in a series of cylinders coaxial to the ion trajectory [ 40 ].…”