Tests of photocathode quantum efficiencies using Cherenkov radiation of electrons from 90Sr (original) (raw)

1994, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

An Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes

2012

ASTeC has spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E. )u p to 20 % at 635 nm [1]. The goal is to use these and other cathode materials in high–average–current high–brightness injectors for particle accelerators. Electron injector brightness is limited by source beam emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread in the emitted electrons, thereby creating a cold beam. We are constructing an experimental system which is compatible with the PPF for measurement of the energy distribution in electrons emitted from photocathodes at room and LN2-temperature. The photocathode will be illuminated by a small, variable–wavelength light spot. The electron beam image will be projected onto a detector comprised of a 3-grid energy filter, a microchannel plate and a phosphor screen. A low–noise CCD camera will capture screen images,...

A correction of the quantum efficiency of cesium iodide and other photocathodes due to the recalibration of the reference photomultipliers

1993

The quantum efficiency (QE) of four photomultipliers of the R1460 series of Hamammatsu, used in the last year as a reference in our ultraviolet-photocathode studies, was determined with the help of a calibrated vacuum ultraviolet-photodiode. Large discrepancies were found with respect to the quantum efficiency curves supplied for each tube by the manufacturer. The correction curves of the photomultipliers are presented and should be used to normalize our previously published quantum efficiency data for various photo-emissive materials. Corrected data of cesium iodide photocathodes are presented here.

Performance of photosensors in high rate environment for gas Cherenkov

arXiv: Instrumentation and Detectors, 2020

The upcoming SoLID experiment at Jefferson Lab will push the envelope on luminosity for a large-acceptance detector, requiring the use of a light-gas Cherenkov detector for trigger-level event selection. Due to the high luminosity environment, the single-photon background rate in this Cherenkov is expected to be extremely high at the photon sensor. Thus, it is essential to validate the planned photosensors and readout electronics to determine the limits of these sensors and mitigate the risk of failure of the trigger-level event selection. We report the design of a small prototype telescopic Cherenkov device and a set of early studies in a high-rate environment in Hall C at Jefferson Lab. Commercially available multi-anode photomultipliers (MaPMT) and low-cost large-area picosecond photodetectors (LAPPD) were tested with the JLab FADC250 modules for the data acquisition to assess their performance in such an environment. The experiment results show that both a MaPMT array and an int...

A 160 keV PHOTOCATHODE ELECTRON GUN TEST FACILITY

2011

We propose the construction of a photocathode electron gun test facility for the characterisation of electron bunches emitted from a GaAs photocathode at room temperature and at LN2 (77 K) temperature, offering diagnostic capa- bilities to measure beam emittance and photocathode re- sponse time as a function of quantum efficiency (Q.E.), based on DC photocathode and photoinjector technology.

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