Self-scanned anode array with a microchannel plate electron multiplier: the SSANACON

Abstract

A unique type of photoelectron counting detector utilizes a 128-element linear self-scanned anode array to collect the output of a dual microchannel plate (MCP) electron multiplier. This detector, developed for the Mariner Jupiter/Saturn Ultraviolet Spectrometer, offers low noise and large dynamic range; having a dark count rate of about 3 × 10⁻³ (anode-sec)⁻¹, it could simultaneously measure two spatially separated signals differing in count rate by more than 6 orders of magnitude. The design of the anode array drew heavily on existing self-scanned photodiode array technology. The 128 narrow aluminum anodes, each 3 mm long, were deposited on 0.1-mm centers for a total collecting area length of 13 mm. The specially designed MCP’s had a rectangular active area corresponding to the collecting area of the anode array. Proximity focusing was employed. Spatial resolution was dependent on the separation and potential difference between the MCP and the anode array. The location of a spectral line could be determined to a fraction of one anode width after a few events had been recorded. Investigations of microchannel plates included measurements of the log-term gain degradation; the MCP gain was found to decrease in relation to the total charge extracted from the plate.