This chapter introduces the production of the positive pions which are needed for the experiment. A general description of the accelerator which delivers the particle beam is presented. The development runs, intended to optimize of the beam channel for pure pion beam and minimal pion stopping volume are also discussed in conjuction with the results of these runs.
The accelerator facility at Paul Scherrer Institute (PSI) offers a large
variety of intense particle beams and irradiation possibilities.
The facility
comprises three cyclotrons known as Injector 1, Injector 2 and the Ring. For
the purposes of the pion beta decay experiment, Injector 2 and the Ring are
relevant. Injector 2 delivers 72 MeV protons to the Ring which in turn
accelerates them to 590 MeV.
These protons are transported to two graphite production targets
of length 
(Target M) and
(Target E)
in the direction of the proton beam.
Table: Properties of the
PSI Ring Accelerator.
At Target E, five secondary beams are
extracted, one of which is the 
beam used by various
experiments including pion beta decay experiment mentioned in the previous
chapter. Some properties of the Ring are summarized in
table 
.