RadPhi TechNote
radphi-2001-402
April 1, 2001
The Radphi experiment requires an energy calibration procedure for the lead glass calorimeter. In the absence of an available source of mono-energetic electrons or photons, the gains of the individual blocks as well as the overall energy scale must be determined based only on characteristic peaks that appear in the invariant mass spectra from reconstructed showers. A procedure is described that reliably extracts absolute gain coefficients for all 620 instrumented blocks from a sample containing of order 105 events. These events are a subset of the standard physics trigger, allowing redundant checks and time-dependent calibration to be carried out after the data are already collected.