A sharp gas-bremsstrahlung beam capable of testing electromagnetic calorimeters

A sharp gas-bremsstrahlung beam with an energy up to 8 GeV is available at insertion device (ID) beamlines at SPring-8. As a practical use of the beam, a test experiment for a 3×33×3 PWO calorimeter has been performed at an ID beamline, BL11XU, to measure the position of the incident gas-bremsstrahlung beam impinging on the calorimeter. The obtained position resolution is ((2.76±0.02)/E)2+(0.30±0.04)2mm, E in GeV, at the center of the calorimeter, which is consistent with the result previously obtained with a low-energy electron beam. Despite limited beam-energy information, the pencil-like photon beam generated on ID beamlines works well for a measurement of the position resolution of electromagnetic calorimeters.