Plutonium-241 as a possible isotope for neutrino mass measurement and capture

Tritium has been the isotope of choice for measurements of the neutrino mass and planned detection of the relic neutrino background. The low mass of $^{3}$H leads to large recoil energy of the nucleus. This has emerged as a limiting factor for both measurements. We investigate $^{241}$Pu as an alternative. The recoil is 80x smaller and it has similar decay energy and lifetime as $^{3}$H. We evaluate for the first time its soft-neutrino capture cross-section and find $(\sigma v)_{\nu} = 1.52 \times 10^{-45}$. This is 40% of the capture cross-section for tritium and makes $^{241}$Pu an interesting alternative for $^{3}$H.