Afterpulses in Photomultipliers

Morton, G. A.; Smith, Harry D.; Wasserman, R.

doi:10.1109/tns.1967.4324452

Cited by 71 publications

(27 citation statements)

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“…Even with a higher threshold, a single photoelectron event can result in a much larger "afterpulse" in the PMT [41,42]. This afterpulse results from contamination of the PMT vacuum over time (especially by helium, which diffuses through glass) and occurs between 400 ns and 600 ns after the initial pulse.…”

Section: Resultsmentioning

confidence: 99%

Magnetic trapping of ultracold neutrons

et al. 2001

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Three-dimensional magnetic confinement of neutrons is reported. Neutrons are loaded into an Ioffe-type superconducting magnetic trap through inelastic scattering of cold neutrons with 4 He. Scattered neutrons with sufficiently low energy and in the appropriate spin state are confined by the magnetic field until they decay. The electron resulting from neutron decay produces scintillations in the liquid helium bath that results in a pulse of extreme ultraviolet light. This light is frequency downconverted to the visible and detected. Results are presented in which 500 ± 155 neutrons are magnetically trapped in each loading cycle, consistent with theoretical predictions. The lifetime of the observed signal, 660 s +290 −170 s, is consistent with the neutron beta-decay lifetime.

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Section: Resultsmentioning

confidence: 99%

Magnetic trapping of ultracold neutrons

et al. 2001

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“…PMT afterpulses are parasitic signals composed of single or few photoelectrons, following a true scintillation event. They originate in residual gas atoms or molecules within the PMT, backflowing towards the photocathode or dynodes after their ionization by the electronic cascade from the primary event [106][107][108][109][110]. The bulk majority of PMT afterpulses appear a maximum of ∼15 µs after the primary, and hence the conservative length for this pretrace (specifically for the ET9390KB, this maximum delay has been reported to be ∼3 µs [111]).…”

Section: Methodsmentioning

confidence: 99%

Search for a nonrelativistic component in the spectrum of cosmic rays at Earth

Collar

2018

Phys. Rev. D

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Dark matter particles gravitationally bound to our galaxy should exhibit a characteristic speed distribution limited by their escape velocity at the position of the Earth (vesc 550 km/s). An ongoing search for anomalous cosmic rays at Earth, kinematically similar to cold dark matter, is described. The technique can discriminate between these and known slow-moving particles such as neutrons, would be sensitive to telltale signatures from presently unexplored candidates, and offers the possibility of identifying the mediating type of interaction (nuclear vs. electron recoils). Studies of background identification and abatement in a shallow underground site are presented. The expected reach of the method is discussed, and illustrated by obtaining the first limits for dark matter particles lighter than 100 MeV/c 2 interacting via nuclear recoils. PACS numbers: 95.35.+d, 96.50.Zc, 29.40.Mc

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“…1) PMT Afterpulsing: Exploration into the chemical and physical nature of PMT afterpulsing effects [33]- [35] showed that diffusion of trace gases through the tube envelope contributed to an increase in the probability of pulse formation. In particular, diffused helium was found to be the main source of afterpulses in tubes that are more than two years old.…”

Section: Causes Of Image Ghostingmentioning

confidence: 99%

Shallow Bathymetric Mapping via Multistop Single Photoelectron Sensitivity Laser Ranging

Shrestha

Carter

Slatton

et al. 2012

IEEE Trans. Geosci. Remote Sensing

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We discuss the optimization of components in a single-wavelength airborne laser bathymeter that is intended for a low-power unmanned aerial vehicle platform. The theoretical minimum energy requirement to detect the submerged sea floor in shallow (< 5 m) water using a low signal-to-noise ratio (LSNR) detection methodology is calculated. Results are presented from tests of a prototype light detection and ranging (LiDAR) instrument that was developed by the University of Florida, Gainesville. A green wavelength (532 nm), 100-beamlet, low-energy (35-nJ/beamlet), short-pulse (480 ps) laser ranging system was operated from a low-altitude (500-m) aircraft, with a multichannel sensor that is capable of single photoelectron sensitivity and multiple stops. Data that were collected during tests display vertical structure in shallow-water areas based on fixed threshold crossings at a single-photon sensitivity level. A major concern for the binary detection strategy is the reliable identification and removal of noise events. Potential causes of ranging errors related to photomultiplier tube afterpulsing, impedance mismatching, and gain block overdrive are described. Data collection/processing solutions based on local density estimation are explored. Previous studies on LSNR performance metrics showed that short (15-cm) dead time could be expected in the case of multiple scattering objects, indicating the possibility of seamless topographic/bathymetric mapping with minimal discontinuity at the waterline. LiDAR depth estimates from airborne profiles are compared to on-site measurements, and near-shore submerged feature identification is presented.Index Terms-Airborne laser swath mapping (ALSM), bathymetry, light detection and ranging (LiDAR), photonics.

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Afterpulses in Photomultipliers

Cited by 71 publications

References 0 publications

Magnetic trapping of ultracold neutrons

Magnetic trapping of ultracold neutrons

Search for a nonrelativistic component in the spectrum of cosmic rays at Earth

Shallow Bathymetric Mapping via Multistop Single Photoelectron Sensitivity Laser Ranging

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