Vol.:(0123456789) 1 3 Journal of Radioanalytical and Nuclear Chemistry https://doi.org/10.1007/s10967-019-06826-w Measurement of neutron dose from p+ 181 Ta reaction at different proton energies via LET spectrometry G. S. Sahoo 1  · S. P. Tripathy 1,3  · S. Paul 1  · S. C. Sharma 2  · D. S. Joshi 1  · T. Bandyopadhyay 1,3  · M. S. Kulkarni 1,3 Received: 25 March 2019 © Akadémiai Kiadó, Budapest, Hungary 2019 Abstract While measuring the neutron dose in accelerator radiation environment using CR-39 detector for radiation protection purpose, LET (linear energy transfer) spectrometry method is implemented when the information about the radiation source term is unknown. In this work, the neutron dose has been measured for p+ 181 Ta reaction at different proton energies i.e. 8–20 MeV by LET spectrometry method using CR-39 detectors. The track density in CR-39 was found to increase exponentially with the proton energy and an empirical relation has been established. The dosimetric quantities viz. absorbed dose (D LET ) and dose equivalent (H LET ) were determined from the LET spectra and both these quantities were found to be increasing with the proton energy. Empirical relations were generated, which will be useful for predicting dose in similar radiation environ- ment. The dosimetric data generated in this study would be useful for radiation protection of occupational workers working in the accelerator radiation environment. Keywords LET spectrometry · Neutron dosimetry · CR-39 detector · p+ 181 Ta reaction · Dose equivalent Introduction The radiological risk from ionizing radiation depends on both the quantity and the quality of the radiation. The radia- tion quantity is the measure of the absorbed dose by the primary as well as the secondary ionizing radiation whereas the radiation quality is best understood by the procedures of microdosimetry where the spatial distribution of the energy deposition plays the major role. The well known instrument for the practice of microdosimetry is TEPC (tissue equiva- lent proportional counter) [1] which measures the distribu- tion of lineal energy transfer. The major limitations of TEPC lie in the domain of high dose rate and in the presence of intense low LET (linear energy transfer) radiations. Hence, LET spectrometer [2] based on SSNTD (solid state nuclear track detector) has been developed which has advantage of measuring the high LET particles in the presence of intense low LET radiations. In the accelerator radiation environ- ment, the presence of low LET gamma radiation makes the neutron dosimetry complicated [3]. Hence the LET spec- trometry method [4] by using CR-39 SSNTD is preferred as it is insensitive to gamma radiation. This method does not involve the complicated unfolding procedures [5] as needed in case of energy spectrometry. Also this method is simple, convenient and does not require the discrimination of differ- ent radiation components. LET spectrometry method for neutron dosimetry has successfully been implemented for cosmic rays [6, 7], high energy 12 C beams [8], mono-energetic neutrons [9], D–T neutrons [10], neutrons produced in p+ 9 Be, p+ 12 C reactions [11, 12] and in combination of 7 Li and 181 Ta target [13]. In this work, the neutron dose has been measured for p+ 181 Ta reaction at different proton energies i.e. from 8 to 20 MeV by LET spectrometry method. Although the p+ 181 Ta reac- tion has been studied earlier [14], the emphasis was given on the determination of neutron spectrum (energy distribu- tion) from the track parameters. However, in this work it is focused on the determination of LET spectra for p+ 181 Ta reaction, without determining the energy spectrum. Tanta- lum is often used in accelerator components such as beam dump, target holder and other structural components and * G. S. Sahoo sahoo.gouri232@gmail.com 1 Health Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India 2 Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India 3 Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India