Proposed neutron lifetime measurement using a hybrid magnetic trap for ultra-cold neutrons

Current values of the neutron ββ-decay lifetime have come under scrutiny due to a large disagreement between recent precise measurements using trapping of ultra-cold neutrons (UCNs) in material bottles. These measurements involve extrapolation procedures to correct the observed storage times for neutron losses due to interactions with material walls. Magnetic trapping of UCNs avoids neutron–matter interactions and thus offers an alternative technique with different systematics. We present our plans toward a new neutron lifetime measurement using a hybrid Ioffe-type trap made with a Halbach-type permanent octupole magnet combined with superconducting coils. The proposed experimental procedure extracts into vacuum UCNs produced from a superfluid helium converter through a moving thin foil and detects the neutron decays via live extraction of produced protons.