A cross-field photomultiplier with sub-nanosecond risetime suitable for nuclear studies

A high-speed photomultiplier using crossed electric and magnetic fields has been made with a useful cathode area 1 cm x 2 cm. The output pulse risetime is 300 pS and full width at half maximum is 500 pS. This is shown to be close to the theoretical limits for this type of tube. Gain is about 10⁷ and output is on two 50-ohm coaxial connectors.