Date of Original Version
The neutron lifetime has been measured by counting the neutrons remaining in a fluid-walled bottle as a function of the duration of storage. Losses of neutrons caused by the wall reflections are eliminated by varying the bottle volume-to-surface ratio. The result obtained is τβ=887.6±3 s.
Mampe, W., Ageron, P., Bates, C., Pendlebury, J. M., & Steyerl, A. (1989). Neutron lifetime measured with stored ultracold neutrons. Physical Review Letters, 63(6), 593-596. doi: 10.1103/PhysRevLett.63.593
Available at: http://dx.doi.org/10.1103/PhysRevLett.63.593