Year
2016
Abstract
In this work, we attempt to identify the isotopic composition of two plutonium-beryllium samples at the Indian Institute of Technology – Kanpur. The sources are approximately forty five years old and all the details are not readily available. Although, the plutonium samples are known to be comprised of Pu-238, some recent measurements have reported presence of primarily Pu-239 along with some other isotopes. In this study, we attempt to identify the exact composition of the Pu-Be neutron sources. Plutonium decays primarily by emitting alpha particles and sometime by spontaneous fission. Alpha decay leads to daughter nuclides which are in excited energy states when formed. These excited nuclides de-excite by emitting gamma-rays to return to their ground states. Measurements of these gamma rays form the basis of the identification of plutonium in different samples. Gamma-ray spectroscopy is one of the most widely used and most accurate way of determining information regarding radioactive materials. In this paper, we utilize the gamma-ray spectra obtained using a high purity germanium (HPGe) detector and a NaI detector for the identification of plutonium isotopes in the PuBe neutron source. In order to confirm the presence of plutonium, a number of gamma-ray peaks need to be observed. Utilizing the information obtained from gamma-ray spectra, the isotopic ratio can be estimated. To determine the ratio between two isotopes of the same element, the net peak areas of the gamma-ray peaks have to be been compared.