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arXiv · 2603.25376

Further search for magnetic-field-induced neutron disappearance in an ultracold neutron beam

Gaby Brenot·Benoit Clément·Hanno Filter-Pieler·Daniel Galbinski·Tobias Jenke·Thomas Lefort·Anthony Lejuez·Guillaume Pignol·Stephanie Roccia·William Saenz-Arevalo
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Abstract

We report the results of the second iteration of an experiment searching for neutron-hidden-neutron oscillations in a beam of ultracold neutrons, conducted at the PF2 facility of the Institut Laue Langevin (ILL). Oscillations were tested via neutron disappearance as a function of an applied magnetic field, in the context of a phenomenological two-parameter model assuming zero hidden potentials. The magnetic field was varied in a step-wise manner in order to resonantly enhance the oscillation probability at different mass splittings ($\delta m$) across a 60--1550 peV range. No evidence for neutron disappearance is observed and conservative limits on the neutron-hidden-neutron oscillation period ($\tau_{nn'}$) have been set at 95 % confidence level: $\tau_{nn'} > 200$ms for $|\delta m| \in [60, 400]$ peV and $\tau_{nn'} > 100$ ms for $|\delta m| \in [400, 1550]$ peV

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Gaby Brenot, Benoit Clément, Hanno Filter-Pieler, Daniel Galbinski, Tobias Jenke, Thomas Lefort, Anthony Lejuez, Guillaume Pignol, Stephanie Roccia, William Saenz-Arevalo. 2026-03-26. Further search for magnetic-field-induced neutron disappearance in an ultracold neutron beam. https://arxiv.org/abs/2603.25376

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