Dark noise in microchannel plate X-ray detectors

Abstract We present a detailed study of dark noise sources in microchannel plate (MCP) X-ray detectors. Previously postulated noise mechanisms are critically reviewed. Noise measurements carried out in the light of the review are then reported. The sea-level background count rate in two-stage MCP detectors is shown to have two principal components. 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 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. Based on this identification of noise sources, prospects for the production of ultralow-noise MCP detectors for imaging X-ray astronomy are discussed. Measurements of noise reduction by coincidence methods using a partitioned anode are described.

[1]  E. Mathieson,et al.  Microchannel plate read-out using graded-density electrodes , 1982 .

[2]  J. G. Timothy,et al.  Curved‐channel microchannel array plates , 1981 .

[3]  D. Werthimer,et al.  Microchannel Plate EUV Detectors for the Extreme Ultraviolet Explorer , 1984, IEEE Transactions on Nuclear Science.

[4]  I. Mason,et al.  The EXOSAT Imaging X-Ray Detectors , 1984, IEEE Transactions on Nuclear Science.

[5]  Shigeru Okabe,et al.  Generalized semiempirical equations for the extrapolated range of electrons , 1972 .

[6]  R. Malina,et al.  Investigation of Large Format Microchannel Plate Z Configurations , 1985, IEEE Transactions on Nuclear Science.

[7]  Ulrich G. Briel,et al.  The Einstein /HEAO 2/ X-ray Observatory , 1979 .

[8]  G. Fraser.  The soft X-ray quantum detection efficiency of microchannel plates , 1982 .

[9]  G. W. Fraser,et al.  The characterisation of soft X-ray photocathodes in the wavelength band 1-300 Å. I. Lead glass, lithium fluoride and magnesium fluoride , 1983 .

[10]  G. W. Fraser,et al.  The Gain Characteristics of Microchannel Plates for X-Ray Photon Counting , 1983, IEEE Transactions on Nuclear Science.

[11]  S. Smith,et al.  High Gain Micro-Channel Plate Multipliers for Particle Tracking or Single Photo-Electron Counting , 1980, IEEE Transactions on Nuclear Science.

[12]  J. Bateman.  The detection of minimum ionising charged particles in channel plate electron multipliers , 1977 .

[13]  James F. Pearson,et al.  Soft X-ray energy resolution with microchannel plate detectors of high quantum detection efficiency. , 1984 .

[14]  James F. Pearson,et al.  The stability of CsI-coated microchannel plate X-ray detectors , 1984 .

[15]  S. Seltzer,et al.  Calculation of radioactivity induced in gamma-ray spectrometers during spaceflight , 1980 .

[16]  E. Kankeleit,et al.  Measurement of the detection efficiency of microchannel plates for 1–15 keV electrons , 1986 .

[17]  J. Culhane.  X-ray instrumentation in astronomy , 1986 .

[18]  D. G. Smith.  Channel multiplier operation in a reduced temperature environment , 1969 .

[19]  R. L. Bybee,et al.  Effects of 1-MeV gamma radiation on a multi-anode microchannel array detector tube. , 1979, The Review of scientific instruments.