The thin film PVA (polyvinyl alcohol) - bromocresol green (∼15µm) dosimeter was made for the applications in radiation technology. It’s parameters before and after gamma irradiation have been studied using optical spectrometer UV-VIS JASCO-V-350 and film densitometer X-Rite Model 301. The results show that the specific wavelength of thin film is ∼ 625nm and the sensitivity of thin film dosimeter is ∼ × 10−3 Gy−1 in the dose range from 1 kGy to 140 kGy. The dose response function of dosimeter was clearly described by the theory of energy transfer model. | Communications in Physics, Vol. 23, No. 2 (2013), pp. 179-184 THE THIN FILM PVA – BROMOCRESOL GREEN DOSIMETER NGUYEN VAN DUNG Hanoi University of Minning and Geology Dong Ngac, Tu Liem, Hanoi Received 16 May 2013; revised manuscript received 21 June 2013 Accepted for publication 27 June 2013 Abstract. The thin film PVA (polyvinyl alcohol) - bromocresol green (∼15µm) dosimeter was made for the applications in radiation technology. It’s parameters before and after gamma irradiation have been studied using optical spectrometer UV-VIS JASCO-V-350 and film densitometer X-Rite Model 301. The results show that the specific wavelength of thin film is ∼ 625nm and the sensitivity of thin film dosimeter is ∼ × 10−3 Gy−1 in the dose range from 1 kGy to 140 kGy. The dose response function of dosimeter was clearly described by the theory of energy transfer model. I. INTRODUCTION Polyvinyl alcohol is excellent matrix for radiochromic centres and widely used for high dose dosimetry purpose [1-3]. An important feature of a dosimeter is its dose-response, which is often expressed as a set of exposure calibration factor at different absorbed doses. A desirable characteristic of dosimeter must be the minimal variation in sensitivity over a wide range of doses. The clear PVA films were studied for high dose dosimetry in [4]. The dyed PVA films with multi-wavelengths in absorbance spectrum were also studied [5, 7]. In present work the dose-response of PVA film dyed by bromocresol green is introduced. The sensitivity of the film is determined in a wide range of doses. II. DOSE-RESPONSE OF THE FILMS According the energy transfer model, an interested dosimeter is considered as a collective acting aggregate of numerous identical radiation sensitive elements. These sensitive elements are uniformly distributed in the dosimeter [6]. The gamma irradiation leads to the formation of activated elements from the sensitive ones. The correlation between number of activated elements n(D) at .
