ABSTRACT
As the determination of the decay constant only requires a relative determination of the count rates, the problems associated with absolute flux determination and detector efficiency are avoided. Also, since the ultra-cold neutron (UCN) beams are low flux and can be turned off during the neutron counting procedure, detector background ceases to be a problem. Neutron storage measurements thus avoid all of the problems inherent in conventional beam techniques. Unfortunately, UCN storage experiments have a few of their own particular problems, all of which are associated with eliminating the contribution of wall loss to the decay time. The use of an ultra low loss surface, low energy UCN and a geometry give a long mean free path between wall collisions which makes the wall loss rate negligible. An important advantage of bottled UCN over beam experiments is that the timing conditions are the same for all neutrons.
