Characterisation and magnetic field properties of multianode photomultiplier tubes

We report on studies of the Hamamatsu model R11265 Multianode Photomultiplier as part of the effort to qualify their use in the upgrade of the LHCb Ring Imaging Cherenkov Detectors. Comparisons with the known model R7600 are also made. Of particular interest is the behaviour of the MaPMT in magnetic fields comparable to the residual fringe field of the LHCb bending magnet ranging up to 25 Gauss.