Correction for PMT temperature dependence of the LHCf calorimeters

LHCf is an experiment to measure the very forward production of particles at LHC in order to calibrate the hadronic interaction models used to simulate cosmic-ray air showers. The results obtained from √s = 7 TeV proton-proton collisions have large systematic errors resulting from the energy scale shift of the reconstructed π(0) mass. It was found that one of the major sources of this shift is the temperature dependence of the PMT response used in the LHCf detectors. In order to correct the variation of the PMT gain by temperature, two types of temperature variation were considered. As a result, systematic errors resulting from the energy scale of Arm2 was improved by 30 %.