A new approach for high-dose measurement using CR-39 track detector
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A new approach for high‑dose measurement using CR‑39 track detector G. S. Sahoo1 · S. P. Tripathy1,3 · Rahul Roy2 · D. S. Joshi1 · M. S. Kulkarni1,3 Received: 20 January 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract To overcome the limitation of CR-39 at high dose region where large number of tracks are overlapped, the FTIR spectroscopic technique can be implemented for dose estimation. In the present work, CR-39 detectors were irradiated with alpha particles from 239Pu source having known doses up to 5.12 Gy. The detectors were subjected to chemical etching in steps of 1 h and subsequently FTIR spectra were recorded. Three strong bands i.e., 1800–1675 cm−1, 1350–1150 cm−1 and 810–760 cm−1 in the FTIR spectra were analysed to study the effect of etching and dose on the peak absorbance of these bands. The peak absorbance was found to decrease with the dose as well as with etching duration and the saturation effect in the peak absorbance was observed above 3 h etching. Etching duration of 2 h was found to be optimal etching time where the linear response was observed up to 5.12 Gy. Furthermore, the threshold for dose estimation by the FTIR spectroscopic technique was observed to be 0.41 Gy, above which this technique can be used. Empirical relations correlating the peak absorbance and dose were generated which can be used as calibration factors for dose estimation in the range 0.41–5.12 Gy using the peak intensity in FTIR spectrum of CR-39 detector. Keywords CR-39 detector · SSNTD · Dosimetry · FTIR · Chemical etching · Peak absorbance
Introduction CR-39 track detector is one of the solid state nuclear track detectors (SSNTDs) widely used for neutron spectrometry and dosimetry [1, 2], measurement of cosmic ray [3], radiobiological experiments [4, 5], measurement of radon/thoron concentration [6]. The detection principle in CR-39 is based on the formation of tracks in the detector material by passage of charged particle. The tracks are then enlarged by one of the etching techniques such as chemical etching [7], electro-chemical etching [8], ultrasonic chemical etching [9] or microwave induced chemical etching [10] and then counted or analyzed by the optical microscope. The counting of the tracks by optical microscope is possible when the * G. S. Sahoo [email protected] 1
Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
2
Radiation Safety Systems Division, HS&EG, Tarapur 401 504, India
3
Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India
tracks are well separated from each other. However there exist some possibilities of counting few overlapping tracks in the track images by segregating the tracks through available image analysis software. But it is tedious, inaccurate and almost impossible when large number of overlapping tracks occurs and the tracks are indistinguishable from each other especially at very high particle fluence or dose. To overcome this complication, FTIR (Fourier transform infrared) spectroscopic technique can be imp
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