Measurement of the neutron lifetime with ultra-cold neutrons stored in a magneto-gravitational trap

International audienceWe report a measurement of the neutron lifetime using ultracold neutrons stored in a magneto-gravitational trap made of permanent magnets. Neutrons surviving in the trap after fixed storage times have been counted and the trap losses have continuously been monitored during storage by detecting neutrons leaking from the trap. The value of the neutron lifetime resulting from this measurement is τ$_{n}$ = (878.3 ± 1.6$_{stat}$ ± 1.0$_{syst}$) A unique feature of this experiment is the monitoring of leaking neutrons providing a robust control of the main systematic loss

Magnetic storage of UCN for a measurement of the neutron lifetime

International audienceWe present the status of an experimental setup designed and built for the measurement of the neutron lifetime and we describe also details about the measuring sequence. The central element of the setup is a magnetic trap made of permanent magnets. Neutrons surviving in the trap after fixed storage times are counted after their extraction and the trap losses are continuously monitored during the storage periods. The technique has achieved a statistical sensitivity of about 2 s on the storage time what constitutes the most sensitive magnetic trapping technique for ultra-cold neutrons developed so far