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Oswald H W Siegmund - One of the best experts on this subject based on the ideXlab platform.

  • response of a lead free borosilicate glass Microchannel Plate to 14 mev neutrons and γ rays
    Review of Scientific Instruments, 2019
    Co-Authors: C E Parker, J A Frenje, Oswald H W Siegmund, C J Forrest, Yu V Glebov, J Kendrick, C W Wink, Gatu M Johnson, T J Hilsabeck, S Ivancic
    Abstract:

    In Microchannel Plate applications, such as in space telescopes, night-vision devices, or time-of-flight particle detection, reducing the sensitivity to signals from background sources, such as γ-rays, is beneficial for the system design and performance. The response of a single-stage lead-free borosilicate-glass Microchannel Plate to 14-MeV neutrons and γ-rays produced via (n, γ) reactions in surrounding structures was investigated at OMEGA. The average efficiency values for secondary electron production were found to be (5.1 ± 0.7) × 10−3 for 14-MeV neutrons and (4.9 ± 1.1) × 10−3 for ⟨1.5⟩-MeV γ-rays.In Microchannel Plate applications, such as in space telescopes, night-vision devices, or time-of-flight particle detection, reducing the sensitivity to signals from background sources, such as γ-rays, is beneficial for the system design and performance. The response of a single-stage lead-free borosilicate-glass Microchannel Plate to 14-MeV neutrons and γ-rays produced via (n, γ) reactions in surrounding structures was investigated at OMEGA. The average efficiency values for secondary electron production were found to be (5.1 ± 0.7) × 10−3 for 14-MeV neutrons and (4.9 ± 1.1) × 10−3 for ⟨1.5⟩-MeV γ-rays.

  • high performance Microchannel Plate imaging photon counters for spaceborne sensing
    Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 2006
    Co-Authors: Oswald H W Siegmund, John V. Vallerga, B Y Welsh, A S Tremsin, J B Mcphate
    Abstract:

    The unique ability to record photon X,Y,T high fidelity information has advantages for high speed recording devices for some important time dependent applications. For Microchannel Plate sensors our most commonly used readout configuration is the cross delay line anode. We have achieved resolutions of 2.5k x 2.5k resolution elements) with excellent linearity for random photon rates of > 500 kHz, while time tagging events using the MCP output signal to better than 100 ps. Open face and sealed tube Microchannel Plate cross delay line detectors of this kind have been built and used for observation of flare stars, orbital satellites and space debris with the GALEX satellite, time resolved imaging of the Crab Pulsar with a telescope as small as 1m, biological fluorescence imaging and synchrotron diagnostics. To achieve better efficiency, higher counting rate and extended lifetime we are now developing cross strip anode readouts. These have already demonstrated 5μm resolution at <10x lower gain than the cross delay line schemes, and high speed electronics for the cross strip are currently in development.

  • next generation Microchannel Plate detector technologies for uv astronomy
    Proceedings of SPIE, 2004
    Co-Authors: Oswald H W Siegmund, John V. Vallerga, J B Mcphate, A S Tremsin
    Abstract:

    Objectives for the next generation of UV Microchannel Plate astronomical detectors include development of efficient photocathodes, including gallium nitride (GaN), and diamond, and optimization of silicon based MCPs. Goals include the development of GaN photocathodes in sealed tube and open detectors with >50% DQE in the UV (>110nm), with tunable cutoffs around 400nm. Activated diamond photocathodes with >40% DQE @ >110nm, cutoffs >200nm, and their application to Si MCPs are also of interest. GaN photocathodes have been developed with efficiencies >60% and cutoffs of ~380nm. Diamond photocathodes with ~40% efficiency at 40nm have been achieved, and Cs activation shows promise for high efficiencies (>20% at 180nm). Silicon based MCPs have qualities that make them preferable to glass MCPs (very low intrinsic background, low fixed pattern noise). Large 8cm Si MCPs have been fabricated with large open area ratio, good lifetest data has been obtained, and techniques for coating high temperature/robust photocathode layers have been explored. We also report on a novel MCP imaging readout scheme, the Cross Strip (XS). This anode uses charge division, and centroiding, of Microchannel Plate charge signals detected on two orthogonal layers of sense strips to encode event X-Y positions, time tags and signal amplitudes. The XS anode is fabricated as a multilayer ceramic/metal structure that can be implemented in a footprint that is not much larger than the active area, and may accommodate formats up to 10cm x 10cm. To date the XS scheme has been tested with a 32 mm x 32 mm prototype anode and customized electronics. This has demonstrated excellent resolution (<7μm FWHM, ~5k x 5k resolution elements (limited by the MCP pore size)) using low MCP gain (~4 x 105), with anode & electronics resolution of ~3μm FWHM.

  • High-performance Microchannel Plate detectors for UV/visible astronomy
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2004
    Co-Authors: Oswald H W Siegmund
    Abstract:

    Abstract Recent advances in basic Microchannel Plate detector technology include new photocathodes such as diamond and GaN with high UV efficiency (up to >50%), silicon-based Microchannel Plates with low fixed pattern noise and background event rates less than 0.02 events cm−2 s−1. In combination with cross-strip photon counting readouts with spatial resolutions of

  • advances in Microchannel Plate detectors for uv visible astronomy
    Astronomical Telescopes and Instrumentation, 2003
    Co-Authors: Oswald H W Siegmund
    Abstract:

    Advances in photocathodes (GaN, Diamond, GaAs), Microchannel Plates (Silicon MCP's), and readouts (Cross strip) are poised to make a significant impact on the capabilities of future space instruments. Alkali halide cathode efficiencies have been improved and GaN photocathodes have achieved >30% DQE in the UV with a bandpass limit of ~400nm. In addition diamond photocathodes have been made with 40% DQE and bandpass up to 200nm, and GaAs photocathodes with ~50% DQE in the visible have been made. This offers the potential for efficient photon counting from 10 - 900nm. Silicon MCP's of 25mm format with ~7μm pores, have been made, achieving gain of nearly 104 for a single Si MCP. The quantum detection efficiency for Si MCP's is the same as glass MCP's, but the background is as low as ~ 0.02 events sec-1 cm-2, the best for any MCP. Flat fields are free of any periodic modulation, and the gain uniformity is good. Silicon MCP's have low stopping power for X, gamma and cosmic rays, are stable at high temperatures (>800°C), and chemically compatible with many photocathodes. The cross delay line and cross strip anodes are based on multi-layer metal and ceramic cross strip patterns. Event positions are encoded by the difference of signal arrival times at the anode contacts (delay line) or by direct sensing of the charge on each strip (cross strip) and determination of the charge cloud centroid for each event. The spatial resolution (<5μm) achieved is sufficient to resolve 7μm Microchannel Plate pores while using low MCP gain (≈2 x 106). Image linearity is good enough to see distortions in the Microchannel Plate pore alignment, and the low MCP gain will enhance the overall lifetime of MCP detector systems.

X. Song - One of the best experts on this subject based on the ideXlab platform.

X. Yuan - One of the best experts on this subject based on the ideXlab platform.

Xinfei Hui - One of the best experts on this subject based on the ideXlab platform.

  • a two dimensional position sensitive Microchannel Plate detector realized with two independent one dimensional resistive anodes
    Review of Scientific Instruments, 2018
    Co-Authors: Yangjun Zhang, X. Song, Junliang Liu, Liping Yang, Wei Wang, Xiaona Zhu, Xinfei Hui
    Abstract:

    A two-dimensional position-sensitive Microchannel Plate detector, with a O100 mm sensitive area and equipped with four integrated amplifiers, is realized with a new anode scheme. The anode is constructed by two independent one-dimensional resistive anodes, each consisting of an array of parallel copper strips connected by resistors in series on a printed circuit board (PCB). The arrays are perpendicularly aligned to realize two-dimensional position resolution, with the intervals between the adjacent strips on the PCB nearer to the Microchannel Plate cut out to allow electrons passing through. The detector is tested with an 55Fe x-ray source, and a position resolution of 0.38 mm is achieved.

A. P. Martin - One of the best experts on this subject based on the ideXlab platform.

  • Hard X-ray imaging with Microchannel Plate optics
    Experimental Astronomy, 1998
    Co-Authors: R. Willingale, Adam N Brunton, G W Fraser, A. P. Martin
    Abstract:

    We investigate, by ray-trace simulation, two hard X-ray telescopes based on Microchannel Plate (MCP) optics. The first is the, by now well known, lobster-eye geometry, while the second is a novel design. The second design uses a pair of MCPs with square channels packed in a radial fashion and represents a conical approximation to the Wolter type I configuration. We show that such telescopes can provide X-ray imaging at energies up to 100 keV. Effective area may be scaled arbitrarily by co-aligning many MCP optics. As an example, we calculate that 50 parallel Wolter I units each of 60 mm diameter and 5 m focal length yield a sensitivity of 1 milli Crab at 45 keV in a 105 second integration.