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In this paper, we present our approach to systematically measure numerous performance parameters of microchannel plate photomultiplier tubes. The experimental setups, the analyses and selected results are discussed. Although the techniques used may be different in other locations, the document is intended as a guide for comparable measurements with other types of microchannel plate photomultiplier tubes. Measurements are shown for the following performance parameters: spectral and spatial quantum efficiency, collection efficiency, gain as a function of voltage, position and magnetic field, time resolution, rate capability and lifetime. By using a dedicated 3-axis stepper and an FPGA-based data acquisition system, also inner PMT parameters are measured as a function of the active area, such as relative detection efficiency, dark count rate, time resolution, recoil electron and afterpulse distributions, as well as charge sharing and electronic crosstalk. In addition, some of the parameters are investigated inside a strong magnetic field. For many of these measurements, the change of most setup parameters and the subsequent analysis can be controlled semi-automatically by software scripts. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract The Advanced Topographic Laser Altimeter System (ATLAS) aboard the Ice, Cloud, and land Elevation Satellite‐2 (ICESat‐2) has been making very high resolution measurements of the Earth’s surface elevation since October 2018. ATLAS uses photomultiplier tubes (PMTs) as detectors in photon counting mode, so that a single photon reflected back to the receiver triggers a detection within the ICESat‐2 data acquisition system. However, one characteristic of ICESat‐2 detected photons is the possible presence of afterpulses, defined as small amplitude pulses occurring after the primary signal pulse due to photon arrival. The disadvantage of these afterpulses is that they often confound the accurate measurements of low level signals following a large amplitude of signal and can degrade energy resolution and cause errors in pulse counting applications. This paper discusses and summarizes the after‐pulsing effects exhibited by the ATLAS PMTs based on on‐orbit measurements over different seasons and geographic regions. The potential impacts of these after‐pulsing effects on altimetry and ocean subsurface retrievals are discussed.

The Advanced Topographic Laser Altimeter System (ATLAS) aboard the Ice, Cloud, and land Elevation Satellite‐2 (ICESat‐2) has been making very high resolution measurements of the Earth's surface elevation since October 2018. ATLAS uses photomultiplier tubes (PMTs) as detectors in photon counting mode, so that a single photon reflected back to the receiver triggers a detection within the ICESat‐2 data acquisition system. However, one characteristic of ICESat‐2 detected photons is the possible presence of afterpulses, defined as small amplitude pulses occurring after the primary signal pulse due to photon arrival. The disadvantage of these afterpulses is that they often confound the accurate measurements of low level signals following a large amplitude of signal and can degrade energy resolution and cause errors in pulse counting applications. This paper discusses and summarizes the after‐pulsing effects exhibited by the ATLAS PMTs based on on‐orbit measurements over different seasons and geographic regions. The potential impacts of these after‐pulsing effects on altimetry and ocean subsurface retrievals are discussed. Plain Language Summary: After‐pulsing effects occurring in the ICESat‐2 Advanced Topographic Laser Altimeter System (ATLAS) are characterized from the on‐orbit measurements acquired over different surface types. Multiple echoes due to after‐pulsing effects in the ATLAS photomultiplier tubes (PMTs) are clearly seen below the Earth's surface where the signal should be totally attenuated. The afterpulses captured from on‐orbit measurements are caused by three different reasons: (1) the effects of the dead‐time circuit (∼3 ns) due to PMT saturation; (2) the effects of optical reflections within the ATLAS receiver optical components; (3) PMT afterpulses. The echoes separated by ∼0.45 m are attributed to the effect of the dead‐time circuit (∼3 ns) due to PMT saturation. The echoes at ∼2.3 and ∼4.2 m below the primary surface returns are caused by the optical reflections within the ATLAS receiver optical components, while the echoes from ∼10 to ∼45 m away from the primary surface signal are due to the PMT afterpulses with a longer time delay. The ICESat‐2 ATLAS instrument response is derived from both a measurement of the transmitted laser pulse shape and measured photon events arising from land surfaces with different surface albedos. The ICESat‐2 on‐orbit measurements demonstrate that the ATLAS impulse response during different months and over different surface types is essentially identical. Key Points: The effects of after‐pulsing by the Advanced Topographic Laser Altimeter System (ATLAS) aboard the ICESat‐2 satellite are describedThe transient response of the ATLAS receiver is characterized over different measurement regimesThe potential impacts of these detector artifacts on ICESat‐2 science studies are discussed [ABSTRACT FROM AUTHOR]

In this work we present results of investigations of afterpulses in the photomultiplier tube (PMT) EMI 9235QA built into the Daybreak TL/OSL reader. The amplitudes of pulses and the time intervals between subsequent pulses were recorded using an ultra-fast data acquisition board and a laboratory made multichannel time/amplitude analyzer. We have recorded afterpulses following background (i.e. dark) pulses, pulses induced by single light photons and by high energy photonic radiation from a number of radioactive sources ( 241 Am, 137 Cs, 60 Co, 90 Sr/ 90 Y) with different X/γ energy ranges. The measurements were performed at varying PMT temperatures. Distributions of time intervals between pulses show that there are several kinds of afterpulses, accompanying primary pulses caused by ionizing radiation, that follow with delays between 10 −8 –10 −4 s. In comparison to pulses induced by a single photoelectron, the amplitude of afterpulses varies over a wide range from less than a single photoelectron to around 10 photoelectrons. In the investigated PMT for single light photon pulses we detected 7.5% of afterpulses and for background pulses up to 31% of afterpulses. Random series of afterpulses following primary pulses change the statistical distribution of the number of pulses recorded using a photomultiplier. If the number of primary pulses follows a Poisson distribution, then total counts number has another distribution with its variance greater than the mean, clearly showing an over-dispersion. [ABSTRACT FROM AUTHOR]

Abstract: We present results of the first observation of afterpulses with extremely long (∼120μs) delay time from the main pulse in 8″ classical vacuum photomultipliers. [Copyright &y& Elsevier]

This work illustrates and compares some methods to measure the most relevant parameters of silicon photo-multipliers (SiPMs), such as photon detection efficiency as a function of over-voltage and wavelength, dark count rate, optical cross-talk, afterpulse probability. For the measurement of the breakdown voltage, V B D , several methods using the current–voltage I V curve are compared, such as the "IV Model", the "relative logarithmic derivative", the "inverse logarithmic derivative", the "second logarithmic derivative", and the "third derivative" models. We also show how some of these characteristics can be quite well described by few parameters and allow, for example, to build a function of the wavelength and over-voltage describing the photodetection efficiency. This is fundamental to determine the working point of SiPMs in applications where external factors can affect it. These methods are applied to the large area monolithic hexagonal SiPM S10943-2832(X), developed in collaboration with Hamamatsu and adopted for a camera for a gamma-ray telescope, called the SST-1M. We describe the measurements of the performance at room temperature of this device. The methods used here can be applied to any other device and the physics background discussed here are quite general and valid for a large phase-space of the parameters. [ABSTRACT FROM AUTHOR]