Phys.Rev. C 97, 055503 (2018)

A.P.Serebrov, E.A.Kolomensky, A.K.Fomin, I.A.Krasnoshchekova, A.V.Vassiljev, D.M.Prudnikov, I.V.Shoka, A.V.Chechkin, M.E.Chaikovskiy, V.E.Varlamov, S.N.Ivanov, A.N.Pirozhkov, P.Geltenbort, O.Zimmer, T.Jenke, M.Van der Grinten, M.Tucker

Neutron lifetime measurements with a large gravitational trap for ultracold neutrons

RADIOACTIVITY ¹n(β^-); measured Iβ, T_1/2 of free neutron, storage cycles for two different holding times, temperature dependence of the UCN storage time, inverse UCN loss rate, neutron count rates before (reactor cycle 179) and after (reactor cycle 181) using gravitationally trapped ultra-cold neutrons (UCN) at Institute Laue-Langevin (ILL) using the PF2 MAM UCN beam; deduced trap-neutron collision frequency, systematic error in T_1/2 measurements using Monte Carlo simulations, influence of the residual gas on UCN storage. Comparison with previous experimental values in the last 17 years, and with evaluations by Particle Data Group. Discussed problem of a 3.9σ discrepancy between measurements of half-life of free neutron using neutrons in beams and those with stored ultracold neutrons (UCN).

doi: 10.1103/PhysRevC.97.055503