Estimation of the plutonium isotopic ratio in a plutonium-beryllium howitzer using gamma spectrometry

Abstract

The gamma-ray spectrum of a ²³⁹PuBe neutron source was analyzed to identify and quantify its isotopic composition. In addition to the previously reported ²³⁹Pu isotope, the present work confirms the presence of ²⁴⁰Pu and ²⁴¹Pu. The isotopes' theoretical masses were computed to be 16.1 g ²³⁹Pu, 3.96 g ²⁴⁰Pu, and 1.86 mg ²⁴¹Pu. Based on these, the ²³⁹PuBe neutron howitzer contains 80.24% ²³⁹Pu, 19.73% ²⁴⁰Pu, and 0.03% ²⁴¹Pu. The results will be useful in simulating irradiation systems based on ²³⁹PuBe (e.g., low-dose uniform neutron irradiation system) and verifying dose rates and neutron fluxes for various applications such as neutron activation analysis and detector calibration.