Hybrid Photomultiplier: Its Characterization and Application as a Wide-Dynamic-Range Photon Detector

Abstract

The hybrid photomultiplier (HPMT) is commercially available in proximity- and electrostatically focused versions, and both contain a photocathode and a PIN-diode substrate. This recent addition to the family of photon detectors offers good timing characteristics, reasonable gain, excellent pulse height distribution, and a wide dynamic range. This report provides details on the wiring and characterization of a typical electrostatically focused production device for gain, impulse response, and pulse height and pulse integral linearity. A gain of 1.8 × 103 was obtained at less than the maximum high-voltage bias. The impulse response rise time was 1.0 ns and the fall time was 0.9 ns. The full width at half-maximum (FWHM) of the impulse response was 4.3 ns at 160 V reverse diode bias. The pulse height was linear up to 4.45 × 104 photoelectrons, and the pulse integral was linear up to the maximum tested (2.23 × 105 photoelectrons). The HPMT is not damaged by light levels that are three orders of magnitude beyond the range of linear response for a conventional PMT. Therefore, the HPMT can be directly implemented in spectroscopic applications that previously required elaborate gating schemes to protect a detector from a large optical flash that preceeds a weak subsequent optical event of interest.