Boosting the UCN density at the LANL UCN source using a low enriched uranium fission plate

The unique properties of ultracold neutrons (UCN) make them ideal for precision measurements of neutron properties. With high enough UCN densities, precision measurements can access Beyond the Standard Model (BSM) physics that rivals or surpasses capabilities of high energy physics[1] and other areas of nuclear physics[2] experiments. While measurements at UCN sources with the highest UCN densities[3] have begun to surpass the precision of those made with cold neutrons, discrepancies [4] have arisen that are difficult to resolve with our current sensitivities. Here we present the idea of using a low enriched uranium fission plate to boost the density of the UCN source [5] at Los Alamos National Laboratory (LANL). Preliminary simulations based on minimal modifications to the existing UCN source suggest that a gain of 3 to 10 is possible. The design does present some challenges and we will discuss how we can address these at LANL.





[1] Y. T. Chien, et al., JHEP 1602, 011 (2016)

[2] Hardy, J. C. & Towner, I. S., arXiv:1807.01146. (2018)

[3] Gonzalez, F. M. et al. Phys. Rev. Lett. 127, 162501 (2021)

[4] Castelvecci, D., Nature 598, 549 (2021) [5] T. M. Ito et al., Phys. Rev. C 97, 012501(R) (2018)

[5] T. M. Ito et al., Phys. Rev. C 97, 012501(R) (2018)