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The high energy neutron generation facilities worldwide uses the Li(p,n) system for production of the quasi mono-energetic neutrons from epithermal to few hundreds of MeV. Among the facilities either self-standing thick Li target or Li foil supported on a target assembly is used. In case of a supported Li target, either low or high mass supporting substrates like Al, C, Au, Ta etc. can be used. However, the neutron emission from the supporting substrate can interfere with the Li(p,n) reaction neutrons. In the present study neutron yields from a thin natural Li target supported on the thick natural Ta (high Z) and C (low Z) targets were measured at incident proton energies between 8-20 MeV. The proton irradiation of targets were performed at the Pelletron accelerator Facility, Mumbai and the emitted neutrons were measures at both forward (0°) and lateral (90°) directions with respect to the incident beam. The neutron yield was estimated using the CR-39 detectors and dual scintillator based active neutron spectrometer. A neutron dose equivalent (NDE) meter was also used to measure the neutron ambient dose equivalent at the measurement point. Experimentally measured neutron yields and ambient neutron dose equivalent estimates indicated higher Li(p,n) neutron yield with carbon as the supporting substrate. This is due to fewer self-emissions from natC compared to natTa target. Carbon supporting substrate also ensures improved spectral features of the Li(p,n) emission neutrons and lesser neutron fluence around the source location. This ensures efficient implementation of radiation protection practices with carbon target due to lower neutron fluence around the source compared to tantalum target. Carbon is a favorable supporting substrate compared to high Z-metal targets like Ta for emission neutron studies on Li target at proton energies between 8-20 MeV. [ABSTRACT FROM AUTHOR]

Current research in the accelerator technology is focused towards achieving high energy, intense beams by minimizing conversion losses during beam acceleration. In such high current facilities, induced activity in structural materials become primary concern for radiation protection and materials like Ta and Nb, with low induced activity generation, high corrosion resistance characteristics are preferred along with conventional structural materials. In view of significant use of elements like Nb, Ta and Fe in the proton accelerators, a dose rate measurement and decay study has been carried out. The prompt γ- and neutron doses with residual activity profile from short and long lived isotopes were estimated using γ-ray spectrometric method. [ABSTRACT FROM AUTHOR]

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+181Ta 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 (DLET) and dose equivalent (HLET) 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 environment. The dosimetric data generated in this study would be useful for radiation protection of occupational workers working in the accelerator radiation environment. [ABSTRACT FROM AUTHOR]

Presently accelerator facilities emphasizes on generating charged particles with enhanced energy and flux. The radiation protection practices at these facilities are considered in civil engineering designs and strictly implemented through different administrative, access control measures (Sarkar in Radiat Meas 45:1476–1483, 2010). However, concern arises from induced activities, during maintenance and decommissioning stages, when sections of accelerator and shielding materials become highly radioactive. Major contribution of induced activity arises from stainless steel (SS-304) beam enclosures and Cu-dumps. Present work focuses on the generation of induced radioactivity profiles with delay counting of SS-304 and Cu along with instantaneous gamma and neutron dose rate measurements at various proton energies for source term estimation. [ABSTRACT FROM AUTHOR]