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 × 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 ) 2 mm , 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.