Shutter ratio of a gated ITT F4128 microchannel-plate photomultiplier

Abstract

The shutter ratio of a proximity focused ITT F4128 microchannel-plate (MCP) photomultiplier is investigated for gated photocathode-to-MCP gap voltages. At counter potentials of greater than 3 V, the shutter ratio is better than 1013 for incident light with a wavelength longer than 600 nm.

First results from the LIDAR Thomson Scattering System on JET

“…The three main features of the LIDAR polychromator are extremely high optical throughput of 1 cm 2 -sr, high average transmission of the six spectral channels (about 70%) and rejection of ruby laser stray light by a factor greater than 10 5 . This performance is achieved with a filter polychromator in which the incident light is shone onto a stack of short wave pass interference edge filters with decreasing cut-on wavelengths, the filters being tilted slightly with respect to each other [4]. The transmission bandwidth of a spectral channel observing reflected light from this filter stack is defined by the cut-on wavelengths of two adjacent filters of the stack and by a suitably chosen coloured glass filter in front of each detector.…”

“…Ruby laser stray light pulses arriving at the detectors before the scattered signal are suppressed very effectively (by a factor of 10 13 [4]) by gating the photocathode to MCP gap of the detectors. The flat top of the gate is about 30 ns long and the ringing, coupled to the detector output by the 10 ns risetime/150 V amplitude gating pulse, was reproducible and could be kept to below 10 mV.…”