A 400-μm horizontal resolution was obtained from ion beam generated secondary electrons accelerated to 2.5 keV.

The collected charge is converted to timing signals through specially designed readout electronics based on the MQT300A LeCroy integrated circuit. Vertical position is evaluated from top-to-bottom charge partitioning. The electric charge is amplified and deposited on a double-delay line anode, with differential timing at the two ends providing horizontal position. The MCP detects electrons produced when an MeV ion beam passes through a thin carbon foil placed at 45° with respect to the beam. Each module provides a 10×2 cm 2 active area and together they cover 80% of the split-pole spectrograph focal plane. The position-sensitive focal plane detector system for the trace element accelerator mass spectrometer at the US Naval Research Laboratory consists of 12 microchannel plate detector modules. Measurements of noise reduction by coincidence methods using a partitioned anode are described.

Based on this identification of noise sources, prospects for the production of ultralow-noise MCP detectors for imaging X-ray astronomy are discussed. The second - isotropic, independent of detector bias voltages, time and temperature - is shown to be consistent, in magnitude and in terms of its output charge spectrum, with the results of beta decay from the radioactive potassium content of the multiplier lead glass. The first - variable with position across the MCP and decaying with time under vacuum in a manner dependent on the plate history - is attributed to outgassing of the channel plate structure.

The sea-level background count rate in two-stage MCP detectors is shown to have two principal components. Noise measurements carried out in the light of the review are then reported. Previously postulated noise mechanisms are critically reviewed. We present a detailed study of dark noise sources in microchannel plate (MCP) X-ray detectors.

Dark noise charge