Influence of magnetic fields on serviceability of photoelectron multipliers

Effect of transverse and longitudinal magnetic fields on the output signal amplitude of ten home and two foreign photoelectron multiplier types is investigated. Magnetic intensity changes within the limits from +37 to -37 Oe. In transverse fields measurements are carried out for three angle values (0, 45 and 90 deg) between the transverse magnetic field direction and the photomultiplier plane. The investigation results obtained show that longitudinal magnetic fields affect less the photomultiplier amplitude than transverse ones. Hysteresis effects involving the magnetic hardness of photomultiplier electrode material are characteristic for most home photomultipliers. Change in photomultiplier orientation relative to the transverse magnetic field changes the photomultiplier characteristics not more than by 25%. Effect of orientation on the photomultiplier amplitude in the longitudinal field is absent