  The neutron lifetime is important in understanding the production of light
nuclei in the first minutes after the big bang and it provides basic
information on the charged weak current of the standard model of particle
physics. Two different methods have been used to measure the neutron lifetime:
disappearance measurements using bottled ultracold neutrons and decay rate
measurements using neutron beams. The best measurements using these two
techniques give results that differ by nearly 4 standard deviations. In this
paper we describe a new method for measuring surviving neutrons in neutron
lifetime measurements using bottled ultracold neutrons that provides better
characterization of systematic uncertainties and enables higher precision than
previous measurement techniques. We present results obtained using our method.
