Study of bialkali photocathodes below room temperature in the UV/VUV region

Microchannel plate (MCP) detectors have been the detector of choice for ultraviolet (UV) instruments onboard many NASA missions. These detectors have many advantages, including high spatial resolution (<20 µm), photon counting, radiation hardness, large formats (up to 20 cm), and ability for curved focal plane matching. Novel borosilicate glass MCPs with atomic layer deposition combine extremely low backgrounds, high strength, and tunable secondary electron yield. GaN and combinations of bialkali/alkali halide photocathodes show promise for broadband, higher quantum efficiency. Cross-strip anodes combined with compact ASIC readout electronics enable high spatial resolution over large formats with high dynamic range. The technology readiness levels of these technologies are each being advanced through research grants for laboratory testing and rocket flights. Combining these capabilities would be ideal for UV instruments onboard the Large UV/Optical/IR Surveyor (LUVOIR) and the Habitable Exoplanet Imaging Mission (HABEX) concepts currently under study for NASA's Astrophysics Decadal Survey.

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“…CsI UV efficiency. Both can be combined in a sealed tube MCP Similar results have been obtained in other PMTs 35 & tests 36 .…”

Section: Photocathode Options and Characteristicssupporting

confidence: 68%

Microchannel plate detector technology potential for LUVOIR and HabEx

Schindhelm

Green

Siegmund

et al. 2017

UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX

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“…This effect is more accentuated for bialkali materials, which have the highest photocathode sheet resistance, while multialkali photocathodes are affected much less by the low temperature [236]. The critical temperature, at which a sharp drop in sensitivity of bialkali photocathodes is observed, is related to the illumination intensity and the photocathode diameter [237,238]. For example, it was possible to operate a PMT with 25 mm photocathode diameter at photocurrents of up to 60 pA down to −125 • C, while for a 2-inch PMT at 6 pA photocurrent the sensitivity started to decrease sharply already at −100 • C. In spite of that, bialkali photomultipliers were found to be suitable for most applications using liquid xenon as a scintillator.…”

Section: Photomultiplier Tubesmentioning

confidence: 99%

Liquid noble gas detectors for low energy particle physics

2013

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We review the current status of liquid noble gas radiation detectors with energy threshold in the keV range, which are of interest for direct dark matter searches, measurement of coherent neutrino scattering and other low energy particle physics experiments. Emphasis is given to the operation principles and the most important instrumentation aspects of these detectors, principally of those operated in the double-phase mode. Recent technological advances and relevant developments in photon detection and charge readout are discussed in the context of their applicability to those experiments.

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“…This assumption is not exact, especially for the Am-Be data set, due to the position of the source. Nevertheless, the observed differences on the mean PMT responses for the different data sets are attributed to the increase in the resistivity of the bialkali photocathodes at low temperatures [20,21]. To cope with this well known effect, the PMTs used have a set of metal tracks deposited under the photocathode.…”

Section: Resultsmentioning

confidence: 91%