The Indian Institute of Technology Kanpur (IIT Kanpur) possesses a PuBe neutron source
facility with an initial activity of 5 Ci, dated September 1966 (nearly 50 years ago).
An understanding of the present activity and the rate of its change will allow implementation
of proper radiological safety procedures and future radiological safety planning.
Knowing the absolute neutron flux will help us in future neutron activation studies.
These details are also important to ensure proper security precautions. In our work,
we attempt to identify the isotopic composition to determine the rate of change of
the source and the absolute thermal neutron flux of plutonium beryllium (PuBe) sample
at IIT Kanpur. We have used gamma-ray spectroscopy for determining the isotopic composition
of the PuBe neutron source. After utilizing gamma-ray spectroscopy it is found that
the source is composed of (239)Pu and a small amount of (241)Am is present as an impurity.
The mass ratio of (241)Am to (239)Pu is found to be approximately 18.1µg/g with an
uncertainty of 1.39%. Delayed gamma neutron activation analysis (DGNAA) is used to
determine the thermal neutron flux of the same PuBe neutron source using copper, cobalt,
nickel and cadmium samples. The average thermal neutron flux as calculated from DGNAA
is approximately 1.27×10(3)n/(cm(2)-s) at 1cm above the PuBe neutron source.