SuperSUN, a new superthermal source of ultracold neutrons (UCN) at the Institut Laue-Langevin, exploits inelastic scattering of neutrons in isotopically pure superfluid 4He at temperatures below 0.6K. For the first time, continuous operation with an intense broad-spectrum cold neutron beam is demonstrated over 60 days. We observe continuous UCN extraction rates of 21000s−1, and storage in the source with saturated in-situ density 273cm−3. The high stored density, low-energy UCN spectrum, and long storage times open new possibilities in fundamental and applied physics.
@article{arxiv.2504.13030,
title = {High-Density Ultracold Neutron Source for Low-Energy Particle Physics Experiments},
author = {Skyler Degenkolb and Estelle Chanel and Simon Baudoin and Marie-Hélène Baurand and Douglas H. Beck and Juliette Blé and Eric Bourgeat-Lami and Zeus Castillo and Hanno Filter and Maurits van der Grinten and Tobias Jenke and Michael Jentschel and Victorien Joyet and Eddy Lelièvre-Berna and Husain Manasawala and Thomas Neulinger and Peter Fierlinger and Kseniia Svirina and Xavier Tonon and Oliver Zimmer},
journal= {arXiv preprint arXiv:2504.13030},
year = {2025}
}