Radioanalytical chemistry for nuclear forensics in China:Progress and future perspective

A relatively new branch of science-nuclear forensics,aiming at providing the nature,origin,history and possible trafficking route of seized nuclear materials/devices,has been established and rapidly developed over decades to screen illicit nuclear activities.This highly interdisciplinary science is built upon a foundation of analytical chemistry,radiochemistry,nuclear physics,material sciences,geology,and other scientific disciplines,within which radiochemical methodologies and radioanalytical techniques play a key role.The present review provides a brief overview about the crucial aspects of nuclear forensics,including basic content,procedure,concerned elements,common separation,analytical method,and so on.The state of the art and recent progresses of nuclear forensics by research communities in China are reviewed,while selected examples and practical applications are emphasized.The challenges associated with this new area and on-going developments are highlighted and discussed.

Correcting for spatially dependent intrinsic efficiency on a germanium double-sided strip detector to improve nuclear forensics response

Purpose The Germanium Gamma-ray Imager(GeGI)is a planar high-purity germanium(HPGe)imaging detector developed by PHDS Co for far-field imaging.This research investigates the detector’s ability for measuring heterogeneous sources in the near field,placed directly on the detector’s faceplate,to perform isotopic mapping for nuclear forensic missions.Methods The intrinsic efficiency is strongly dependent on where the photons interact within the germanium.The efficiency varies by up to 20%within the sensitive volume of the detector.The efficiency was mapped using eight different photons from 123 to 1274 keV emitted from a collimated 154Eu photons.These were measured at 108 locations to interpolate the efficiency at any point on the detector’s face.Results The position and energy dependence are uncorrelated,and thus,the absolute efficiency at any position and for any gamma-ray energy can be calculated by the convolution of the spatial and energy efficiencies.Conclusion The results on this research show that detection efficiency for a planar two-sided strip HPGe is spatially dependent and shows typical energy dependence.The spatial dependence,which does not have any additional energy dependence,can be corrected.A 154Eu source was used in this research and was able to spatially calibrate for photon energies ranging from 100 to 1300 keV.This method is applicable for sources with higher gamma energies.The advantages of the method demonstrated that after initial in-laboratory calibration,a single measurement in the field can be used to efficiently calibrate the HPGe as a function of photon interaction on the crystal.