The PMT Calibration (PCA) is responsible for PMT gain and walk (T v. Q) calibration. Although the two fitting procedures are distinct they have a common user control interface and together describe the process that converts PMT hits into charge and time, and so are grouped together. The PCA currently supports three calibrations: the gain calibration and the walk calibration, versions 1 and 2.
PCA uses Logical Circuit Numbers throughout, with the exception of the Multipoint PCA PMT mask. For details of this numbering system see
Companion / Glossary / Circuit and Cable Numbering SchemesThe Multipoint PCA PMT mask uses tube numbers.
The PCA is designed to calibrate tubes under the assumption that they are hit by single photons. A timing correction for multiphoton hits has been developed and is controlled by the MPC processor. Details regarding running MPC can be found in the MPC section of the user manual.
The Multipoint PCA was developed for the NCD phase. Multiple laserball positions are used to compensate for the shadows cast by the NCDs.