Radiation chemical yields for loss of ether and carbonate ester bonds in PADC films exposed to proton and heavy ion beams

Sudden Increase of the Radiation Chemical Yield for Loss of Carbonate Ester in PADC Detector where the Track Overlapping of 28 MeV Electrons Becomes Significant

“…In our previous studies, we obtained the core radius based on the track overlapping model and the fluence dependence of UV spectra of PADC exposed to protons and heavy ions [12]. The results were concordant to that of loss of ether within the experimental error [3]. We applied this model to the present case, regarding the fluence of 1.6×10 15 electrons/cm 2 as the critical fluence where the overlapping becomes significant, the value of 0.04 nm was derived, which is in the same order to those of considered functional groups here.…”

“…Figure 3 shows reduction of relative absorbance, A/A 0 , of ether, carbonate ester and CH groups, as well as changes in absorbance, A-A 0 , of OH groups as a function of the fluence. The relative absorbance of ether decreases linearly with increasing the fluence, similar to that in the cases of gamma ray, protons and heavy ions [2,3,4]. On the other hand, that of carbonate ester decrease above a certain fluence of 1.6×10 15 electrons/cm 2 .…”

“…5. It is noteworthy that PADC has an exceptional feature that the G values for the losses of ether and other functional groups are larger at the smaller stopping powers for each ion species [1,2,3,4]. The G value for 28 MeV electron is slightly lower than that of gamma rays from Co-60, of which average linear energy transfer, LET, is 0.2 eV/nm, and clearly lower than that of 70 MeV protons.…”

“…The removal cross section is identical for both fluence regions, single-hit zone and multi-hits zone, as listed in Table 1 including the statistical errors. The chemical damage parameters of damaged density, effective track radius and radiation chemical yield were derived from value of the removal cross section [1,3,4]. The effective track radius, in which the considering bonds were lost, was found to be 0.023 nm.…”

“…In our recent studies, latent track structure in Poly(allyl diglycol carbonate), PADC, has been investigated, which have been exposed to protons and heavy ions, covering the stopping powers ranging from 1.2 to 12,000 eV/nm [1,2,3,4]. The PADC is the most sensitive etched track detector, ETD, which is known under the trade name of CR-39.…”