Initial Tests Of The Pion Beta Decay Detector

5.2 Data reduction

The data recorded during the experiment inevitably included events from processes that form a background that must be removed or accounted for in order to see clearly the processes of interest. Examples would be nuclear de-excitations, cosmic rays, or other beam-related particles that came in beam buckets subsequent to the one that carried the initial pion that opened the DPG. Many of these background events can be removed by looking at the timing and signal size of certain detectors.

The data recorded also contained a significant amount of noise introduced by the electronics used in the acquisition. Much of this noise can be corrected for as discussed in section 5.2.2.

Some values of interest cannot be recorded directly online, but must be calculated from other detector values. Examples of these are the energy loss in the plastic veto (the considerable attenuation means the signal amplitudes are not proportional to the energy lost so the geometric mean must be calculated) and the positron energy lost escaping the target (the positron pulse is always riding on some portion of the large pion stopping pulse in the target). These secondary values were calculated prior to cutting any events since some cuts were made on calculated values.