“…In other techniques the assay does not depend on the geometry of the assayed sample. Isotopic ratios of NMs are estimated through utilizing the ratio of simultaneously observed gamma responses from different uranium isotopes, using different X-and/or gamma lines from the same spectrum [13][14][15][16][17][18][19][20][21][22][23]. Monte Carlo (MC) simulation codes could be used for mathematical calibration of the detectors [24][25][26][27][28][29][30][31] to overcome the unavailability of NM standards.…”