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

Tomoya Yamauchi,Masato Kanasaki,Rémi Barillon

doi:10.3390/polym13162665

Abstract

Modified structure along latent tracks and track formation process have been investigated in poly (allyl diglycol carbonate), PADC, which is well recognized as a sensitive etched track detector. This knowledge is essential to develop novel detectors with improved track registration property. The track structures of protons and heavy ions (He, C, Ne, Ar, Fe, Kr and Xe) have been examined by means of FT-IR spectrometry, covering the stopping power region between 1.2 to 12,000 eV/nm. Through a set of experiments on low-LET radiations—such as gamma ray-, multi-step damage process by electron hits was confirmed in the radiation-sensitive parts of the PADC repeat-unit. From this result, we unveiled for the first-time the layered structure in tracks, in relation with the number of secondary electrons. We also proved that the etch pit was formed when at least two repeat-units were destroyed along the track radial direction. To evaluate the number of secondary electrons around the tracks, a series of numerical simulations were performed with Geant4-DNA. Therefore, we are proposing new physical criterions to describe the detection thresholds. Furthermore, we propose a present issue of the definition of detection threshold for semi-relativistic C ions. Additionally, as a possible chemical criterion, formation density of hydroxyl group is suggested to express the response of PADC.

Highlights

IntroductionMore than 40 years have passed since the re-discovery of poly(allyl diglycol carbonate), PADC, as a polymeric etched track detector, which had been developed as an optical plastic material [1]
In etched track detectors and solid-state nuclear track detectors applications, PADC detectors are chemically etched in alkaline solution of NaOH or KOH to enlarge latent tracks of proton and heavy ions to etch pits that are observable under optical microscopes
Modified structure around latent tracks of protons and heavy ions in PADC has been investigated by means of FT-IR spectrometry, covering the stopping powers ranging from

Summary

Introduction

More than 40 years have passed since the re-discovery of poly(allyl diglycol carbonate), PADC, as a polymeric etched track detector, which had been developed as an optical plastic material [1]. PADC detectors are best known under the trade name of CR-39. In etched track detectors and solid-state nuclear track detectors applications, PADC detectors are chemically etched in alkaline solution of NaOH or KOH to enlarge latent tracks of proton and heavy ions to etch pits that are observable under optical microscopes. From the geometry of each etch-pit, it is possible to identify the nuclear species and to evaluate the incident energy. A more detailed description of nuclear track detectors, including fundamental aspects and their applications, can be found in Handbook of Radioactivity

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Conclusion