Studies on pre-irradiation thermal annealing induced new phase formation in a PADC polymer: The influence of phase transition on heavy ion detection

Abstract

Stimulation with thermal pulses can realize and manipulate states of matter with emergent structural and electronic phenomena. The transition phases are often non-transient, and the challenge is to understand them as persistent states. Isochronal annealing experiment at annealing temperatures of 130, 140, 150 and 160 °C for 8 h, was conducted on PADC (so-called CR-39) detectors prior to their irradiation to 252Cf source. Reversing the sequence, other detector films were first subjected to 252Cf irradiation and then thermally treated only at 130 °C for 8 h as above. for example, as a standard comparison between both processes: irradiation post-annealing and irradiation pre-annealing. The bulk etch rates were measured by using the weight loss method (WLM) and the fission track diameter method (FTDM). The qualitative impacts of these treatments have been characterized by means of X-ray diffraction, differential scanning calorimetric (DSC) and spectroscopic measurements of FT-IR. Specifically, the dependences of structural, thermal and chemical parameters on the thermal pulses passed through PADC polymer films treated at different annealing temperatures for annealing time 8 h have been measured. The phase transition of the PADC films was found to be dependent on the annealing temperature, in addition, phase transition proved to be clearly formed by increasing the annealing temperature at 130 °C. This paper shows how the well-controlled thermal treatment of the PADC detector can alter its radiation detection thresholds and its detection sensitivity in the near-surface layer of thickness beyond a couple of hundreds of nanometers. This finding is more pronounced for cases of higher annealing temperatures and larger annealing time intervals. The obtained results demonstrate that the heavy ions (with higher ionization rates e.g., fission fragments), are clearly detected in the near-surface layer of the thermally treated PADC.