Performance studies of microchannel plate PMTs in high magnetic fields

Microchannel plate (MCP) photomultipliers (PMTs) are attractive photon sensors for the PANDA DIRC. The gain and the time resolution of different types of MCP-PMTs were studied as a function of the magnetic field and of the field orientation. It was found that for an efficient single photon detection a pore diameter of 10μm or less will be needed in the 2 T magnetic field of PANDA. Both gain and time resolution are best with a pore size of 6μm. In contrast to the gain the time resolution shows only a weak dependence on the magnetic field and its orientation. The best transit time resolution for single photons was evaluated to be σ≈20ps with no magnetic field applied.