Performance of a scintillating strip detector with G-APD readout

The upgraded KLM detector end cap of Belle II experiment will consist of more than 16 000 scintillating detectors of 0.5–2.8 m long strips. One of possible solutions is presented: a detector of 2800×40×10 mm3 with light readout via WLS fiber and new solid state photo-detector multi-pixel avalanche photo-diode working in Geiger mode. Concept of the mechanical structure of upgraded KLM detector is given. Properties demonstrating the operation capabilities of such a scintillating detector: MIP registration efficiency, noise pulse rate with respect to expected background rate are demonstrated as well as response distributions in longitudinal and transverse directions. Study of radiation damage of photo-detectors shows that Hamamatsu MPPC can be used in Belle II environment during at least 10 years.