A simulation study of the behaviour of fine mesh photomultipliers in magnetic field

Results of a comparison between experimental data and a Monte Carlo simulation study on fine-mesh photomultipliers (PM) behaviour in magnetic field (B) are reported. This work is accomplished in order to understand the details of the electron cascade between the dynodes; the PM amplification gain is investigated, with respect of several relative orientations of the field and the PM axis and for different values of the B-field intensity. Some characteristic of the energy spectrum of the secondary electron emission (SEE) is also taken into account in this work. The aim is to better understand which technical constructive parameters are more sensitive to the optimization of the PM performance in presence of high B-fields (e.g. as required for the KLOE experiment). The simulation results are compared with those experimentally obtained with the Hamamatsu R2490-05 fine mesh tubes.