Keywords: HPGe detectors, background radiation, passive shielding, MDA, minimum detectable activity, graded shielding, continuum, gaseous effluent, integral, FPNG, stack, low radiation, lead, copper, aluminium, radiological protection, nuclear power plants, NPP, nuclear energy
Background minimisation of HPGe detector by passive graded shielding
A simple and economical passive graded shielding which is combination of low and high Z materials for HPGe detector for background radiation minimisation is developed for better identification of the peaks in acquired spectrum by reducing Compton continuum. The present paper discusses the design and advantages of the passive graded shielding (lead + copper + aluminium) which encloses the HPGe detector. The passive graded shielding improved sensitivity of the detector and reduced Minimum Detectable Activity (MDA) for planchet source from 19.6% to 11.7% for gamma photon energies in the range of 81–1408 keV and brought down the MDA, 35.25 GBq d
−1and 35.26 GBq d
135Xe respectively which was 72.31 GBq d
−1and 78.27 GBq d
−1for noble gases in gaseous effluents before shielding of the detector. The passive graded shielding as integral part is considerably very useful for radiological protection at nuclear power/research reactors by minimising background radiation.