M Le Joubioux, H Savajols, W Mittig, X Fléchard, L Hayen, Yu E Penionzhkevich, D Ackermann, C Borcea, L Caceres, P Delahaye, F Didierjean, S Franchoo, A Grillet, B Jacquot, M Lebois, X Ledoux, N Lecesne, E Liénard, S Lukyanov, O Naviliat-Cuncic, J Piot, A Singh, V Smirnov, C Stodel, D Testov, D Thisse, J C Thomas, D Verney
Neutron dark decays have been suggested as a solution to the discrepancy between bottle and beam experiments, providing a dark matter candidate that can be searched for in halo nuclei. The free neutron in the final state following the decay of ^{6}He into ^{4}He+n+χ provides an exceptionally clean detection signature when combined with a high efficiency neutron detector. Using a high-intensity ^{6}He^{+} beam at Grand Accélérateur National d'Ions Lourds, a search for a coincident neutron signal resulted in an upper limit on a dark decay branching ratio of Br_{χ}≤4...
March 29, 2024: Physical Review Letters