The Quadrant Photomultiplier

Persyk, D.E.; Morales, J.; McKeighen, R.E.; Muehllehner, G.

doi:10.1109/tns.1979.4329658

Cited by 9 publications

(2 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Photodetectors employ transmission-mode photocathodes fabricated on transparent substrates, whereas electron guns typically employ reflection-mode photocathodes grown on a variety of electrically conductive substrates [7]. There are a number of documented recipes for fabricating Cs x K y Sb photocathodes for dc high voltage photoguns [8][9][10][11][12][13][14]. Chemicals can be applied to the substrate at the same time (codeposition) or sequentially, using a variety of chemical sources that contain one, two or all three of the chemical species.…”

Section: Introductionmentioning

confidence: 99%

Thermal emittance and lifetime of alkali-antimonide photocathodes grown on GaAs and molybdenum substrates evaluated in a −300 kV dc photogun

Wang

Mamun

Adderley

et al. 2020

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

Cs x K y Sb photocathodes grown on GaAs and molybdenum substrates were evaluated using a −300 kV dc high voltage photogun and diagnostic beam line. Photocathodes grown on GaAs substrates, with varying antimony layer thickness (estimated range from <20 nm to >1 um), yielded similar thermal emittance per rms laser spot size values (∼0.4 mm mrad=mm) but very different operating lifetime. Similar thermal emittance was obtained for a photocathode grown on a molybdenum substrate but with markedly improved lifetime. For this photocathode, no decay in quantum efficiency was measured at 4.5 mA average current and with peak current 0.55 A at the photocathode.

show abstract

Section: Introductionmentioning

confidence: 99%

Thermal emittance and lifetime of alkali-antimonide photocathodes grown on GaAs and molybdenum substrates evaluated in a −300 kV dc photogun

Wang

Mamun

Adderley

et al. 2020

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

show abstract

“…Photoguns typically employ front face illumination of the photocathode surface (not transmission mode), in which case, the thickness of the photocathode is not a limiting factor, at least not in terms of how the light is delivered. However, common recipes for alkali-antimonide fabrication rely on sequential deposition of K and Cs onto a relatively thin Sb layer (~15 nm) [122] similar to recipes used for photomultipliers tubes [123] where the Sb layer must transmit light. During photocathode fabrication, the chamber overall vacuum level and presence of water are known to affect the growth and morphology of Sb films [124][125][126][127].…”

Section: Introductionmentioning

confidence: 99%

Thin film studies toward improving the performance of accelerator electron sources

Mamun

2016

View full text Add to dashboard Cite

Future electron accelerators require DC high voltage photoguns to operate beyond the present state of the art to conduct new experiments that require ultra-bright electron beams with high average current and higher bunch charge. To meet these demands, the accelerators must demonstrate improvements in a number of photogun areas including vacuum, field emission elimination in high voltage electrodes, and photocathodes. This dissertation illustrates how these improvements can be achieved by the application of suitable thin-films to the photogun structure for producing ultra-bright electron beams.This work is composed of three complementary studies. First, the outgassing rates of three nominally identical 304L stainless steel vacuum chambers were studied to determine the effects of chamber coatings (silicon and titanium nitride) and heat treatments. For an uncoated stainless steel chamber, the diffusion limited outgassing was taken over by the recombination limited process as soon as a low outgassing rate of ~1.79(0.05)  10 -13 Torr L s -1 cm -2 was achieved. An amorphous silicon coating on the stainless steel chambers exhibited recombination limited behavior and any heat treatment became ineffective in reducing the outgassing rate. A TiN coated chamber yielded the smallest apparent outgassing rate of all the chambers: 6.44(0.05)  10 -13 Torr L s -1 cm -2 following an initial 90 °C bake and 2(20)  10 -16 Torr L s -1 cm -2 following the final bake in the series. This perceived low outgassing rate was attributed to the small pumping nature of TiN coating itself.Second, the high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, were compared to that of bare aluminum electrodes and electrodes manufactured from titanium alloy (Ti-6Al-4V). This study suggests that aluminum electrodes, coated with TiN, could simplify the task of implementing photocathode cooling, which is required for future high current electron beam applications. The best performing TiNcoated aluminum electrode demonstrated less than 15 pA of field emission current at -175 kV for a 10 mm cathode/anode gap, which corresponds to a field strength of 22.5 MV/m. Third, the effect of antimony thickness on the performance of bialkali-antimonide photocathodes was studied. The high-capacity effusion source enabled us to successfully manufacture photocathodes having a maximum QE around 10% and extended low voltage 1/e lifetime (> 90 days) at 532 nm via the co-deposition method, with relatively thick layers of antimony (≥ 300 nm). We speculate that alkali co-deposition provides optimized stoichiometry for photocathodes manufactured using thick Sb layers, which could serve as a reservoir for the alkali.In summary, this research examined the effectiveness of thin films applied on photogun chamber components to achieve an extremely high vacuum, to eliminate high voltage induced field emission from electrodes, and to generate photocurrent with high quantum yield with an extended operational lifetime. Simult...

show abstract

Test of a new 64-channel PMT for imaging

Comby¹,

Meunier²

1988

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

The Quadrant Photomultiplier

Cited by 9 publications

References 2 publications

Thermal emittance and lifetime of alkali-antimonide photocathodes grown on GaAs and molybdenum substrates evaluated in a −300 kV dc photogun

Thermal emittance and lifetime of alkali-antimonide photocathodes grown on GaAs and molybdenum substrates evaluated in a −300 kV dc photogun

Thin film studies toward improving the performance of accelerator electron sources

Test of a new 64-channel PMT for imaging

Contact Info

Product

Resources

About