Henrikas Svidras ; Markus Röhrken ; Simon Wehle ; Kerstin Tackmann

17 September 2021

Abstract: This note presents photon detection efficiency data-to-simulation ratio distributions in the barrel region of the electromagnetic calorimeter of the Belle II detector at the SuperKEKB asymmetric energy electron-positron collider. They are computed using 71.2 fb−1 of experimental data collected by the Belle II detector and the official Belle II Monte Carlo simulation. An initial-state high energy photon from e+e− → μ+μ−(γISR) is searched by predicting its momentum from missing momentum of the dimuon system. The data-to-simulation ratios of the detection efficiency are presented as functions of missing momentum and its angular directions.

Keyword(s): photon ; efficiency ; gamma ; detection ; ecl ; calorimeter ; performance ; photons ; gammas