Speaker
Description
We report results from a test beam at DESY in which we tested the readout of 32 3 mm thick ATLAS TileCal tiles with wavelength-shifting fibers and a 64-channel SiPM array. Each tile was read out with two wavelength-shifting fibers that were coupled to the SiPM array via an airgap or with grease. For most measurements the beam was perpendicular to the tiles. We measured the relative gain and light yield of each channel. For 3 mm tiles the light yield lies between two and three photoelectrons. To increase the light yield we also sent the beam through the longest side of the tile (about 22 cm). Furthermore, we aimed the beam at different x, y positions to look at the light yield uniformity. We studied the gain as a function of overvoltage and electron energy. We repeated some measurements with a second SiPM array.