A series of neutron lifetime measurements using the beam method has been conducted at the National Institute of Standards and Technology (USA) for more than 30 years. In these experiments, a cold neutron beam passes through a quasi-Penning trap where protons from free neutron decay are captured and subsequently counted by a silicon detector. We will review the previous BL1 experiment (2005,...
The ``neutron lifetime puzzle'' arises from the discrepancy between neutron lifetime measurements obtained using the beam method, which measures decay products, and the bottle method, which measures the disappearance of neutrons.
To resolve this puzzle, we conducted an experiment using a pulsed cold neutron beam at J-PARC. In this experiment, the neutron lifetime is determined from the ratio...
