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

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.

Photoemission and optical constant measurements of a Cesium Iodide thin film photocathode

The performance of cesium iodide as a reflective photocathode is presented. The absolute quantum efficiency of a 500 nm thick film of cesium iodide has been measured in the wavelength range 150 nm to 200 nm. The optical absorbance has been analyzed in the wavelength range 190 nm to 900 nm and the optical band gap energy has been calculated. The dispersion properties were determined from the refractive index using an envelope plot of the transmittance data. The morphological and elemental film composition have been investigated by atomic force microscopy and X-ray photo-electron spectroscopy techniques.

Photoemission and optical constant measurements of Cesium Iodide thin film photocathode

Performance of cesium iodide (CsI) as a reflective photocathode is presented. Absolute quantum efficiency (QE) measurement of 500 nm thick CsI film has been carried out in the wavelength range of 150 nm to 200 nm. Optical absorbance of 500 nm thick CsI film in the spectral range of 190 nm to 900 nm is analyzed and optical energy band gap is calculated using Tauc plot. To see the dispersive behavior of CsI film, refractive index has been determined by envelop plot of transmittance data, using Swanepoel method. Additional information on morphological and elemental composition results of CsI film, gained by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively are also reported in present work.

Performance study of a cesium iodide photocathode-based UV photon detector in Ar/CH 4 mixture

Photon. Res. / Vol. 2, No. 3 , 2014

The detection efficiency of a gaseous photomultiplier depends on the photocathode quantum efficiency and the extraction efficiency of photoelectrons into the gas. In this paper we have studied the performance of an UV photon detector with P10 gas in which the extraction efficiency can reach values near to those in vacuum operated devices. Simulations have been done to compare the percentage of photoelectrons backscattered in P10 gas as well as in the widely used neon-based gas mixture. The performance study has been carried out using a single stage thick gas electron multiplier (THGEM). The electron pulses and electron spectrum are recorded under various operating conditions. Secondary effects prevailing in UV photon detectors like photon feedback are discussed and its effect on the electron spectrum under different operating conditions is analyzed.

Effect of vacuum treatment on CsI photocathode performance in UV photon detectors

OPTICAL MATERIAL EXPRESS, 2013

CsI can be used as a photocathode material in UV photon detectors. The detection efficiency of the detector strongly depends on the photoemission property of the photocathode. CsI is very hygroscopic in nature. This limits the photoelectron yield from the photocathode when exposed to humid air even for a short duration during photocathode mounting or transfer. We report here on the improvement of photoemission properties of both thick (300 nm) and thin (30 nm) UV-sensitive CsI film exposed to humid air by the process of vacuum treatment.Quantum efficiency of cesium iodide photocathodes in the 120-220 nm spectral range traceable to a primary detector standard," Nucl. Instrum. Methods Phys. Res. A 438(1), 94-103 (1999).Production technique and quality evaluation of CsI photocathodes for the ALICE/HMPID detector," Nucl. Instrum. Methods Phys. Res. A 566(2), 338-350 (2006).

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