3.1 The Paul Scherrer Institute accelerator
The accelerator at the Paul Scherrer Institute (PSI) is a vital component of
the pibeta experiment. The PSI facility was chosen because of it the time
structure of its primary production beam. "Buckets" of beam particles are
delivered every 20 ns at PSI as opposed to 5 ns at the Los Alamos Meson Physics
Facility (LAMPF) and 12 ns at the Tri-Universities Meson Facility (TRIUMF). A
longer period between beam buckets makes it easier to distinguish beam pions
from muon and positron contaminants. Additionally, it is easier to reject
events in which two adjacent beam buckets both contain particles. This section
will provide an overview of the accelerator and its components and a
description of how the pion beam used by the pibeta experiment is produced.