High resolution position-sensitive detectors using microchannel plates

The characteristics and performance of several kinds of high-gain micro-channel plate photomultipliers have been investigated. Special attention was directed towards i) lifetime studies, ii) performance in the magnetic field, and iii) timing properties. Lifetime studies include separate investigations of the photocathode quentum efficiency degradation caused by ion feedback, and the deterioration of the micro-channel plate gain. The dependence of the micro-channel plate photomultiplier gain on the intensity and the direction of the magnetic field (up to 7 kGauss) is reported.

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Studies of High-Gain Micro-Channel Plate Photomultipliers

A proto type multianode photomultiplier tube incorporating a chevron type MCPs electron multiplier and 400 multi anodes was developed for high speed image pick-up at low light levels such as in detection of rings of Cherenkov light. The diameter of and mean spacing of each anode are 0.3mm and 0.65mm respectively in a rectangular array of 16mm×12mm. The MCP used in the tube were fabricated at HTV and had 24.9mm diameter, 20mm useful diameter, 15?m pore diameter and 45 length to pore diameter ratio. Electron multiplication and dark current for each MCP were about 104 and 1pA at 1000v respectively. 0.6mm spatial resolution over anode surface and about 600psec rise time of output signal were obtained.

A 400 Anode Chevron Microchannel Plate PMT for High Energy Application

The two most important limitations of the human eye are identified as the spectral range, which can be extended by image converters and sensitivity, which can be augmented by image intensification. Various kinds of converter are discussed and a brief mention of ultrasonic and thermal imaging principles is given. Intensifier tubes are shown to offer a basic improvement in perception at very low light levels, where the quantum nature of light is important. The critical parameters of image intensifier tubes are dealt with, including a brief discussion of various attempts to obtain high brightness gain in intensifier tubes by employing more than one stage of image intensification. This is followed by a description of the phenomenon of channel electron multiplication, and a discussion of its application to image intensifier tubes.

https://iopscience.iop.org/article/10.1088/0022-3735/8/3/001/pdf

Image converters and intensifiers

Chapter 3 – Mass Spectrometric Techniques

Publisher Summary This chapter discusses some design aspects of a small high-contrast channel image intensifier. This channel image intensifier uses an inverting electrostatic lens to focus the electron image from the primary photocathode to the input of the channel plate, and proximity focusing between the channel plate output and the fluorescent screen. The major electron optical-design problem occurs in the inverting section in meeting the principal design requirements of: (1) a flat image plane to match the planar channel-plate input; (2) a resolution performance such that the major effect on the overall modulation transfer is that of the proximity-focused channel plate to screen section, and (3) a diode construction to obviate the need for preset stabilized focusing voltages. The operating voltages required for the tube are 5 kV between the photocathode and input to the channel plate, and a further 5 kV between the channel-plate output and the fluorescent screen. Results demonstrate that a small, high-contrast image intensifier can be manufactured using the channel multiplication principle, which has a performance equal to or better than other types of intensifiers at all but extremely low light levels.

D.L. Emberson

Papers

Some Aspects of the Design and Performance of a Small high-contrast Channel Image Intensifier