A comparative study of microstrip plate geometries as UV photosensors with reflective photocathodes: simulation

Abstract-The performance for X-ray spectrometry of argon-xenon gas proportional scintillation counters (GPSCs) using a CsI-coated microstrip plate in direct contact with the scintillation gas as a vacuum ultraviolet photosensor is investigated for different argon-xenon mixtures. The GPSC/microstrip gas chamber hybrid detectors filled with argon-xenon mixtures present superior performance when compared to those with pure argon and pure xenon fillings. For these mixtures, the signal amplification due to the scintillation processes and the detector energy resolution may achieve values of 15-18 and 11-10%, respectively. The best energy resolutions can be achieved for mixtures with a broad range of xenon concentration, 20-70% Xe, and for lower reduced electric fields in the scintillation region as the xenon concentration is reduced. As in pure argon or pure xenon gas-filling, the detector performance is limited by optical positive feedback resulting from additional scintillation produced in the electron avalanche processes around the microstrip plate anodes. The best energy resolutions are achieved for positive feedback gains of about 1.1.

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“…Improvements can be obtained using MSPs with larger cathode-to-anode gap spacing and larger cathode strips [6].…”

Section: Introductionmentioning

confidence: 99%

The performance of the GPSC/MSGC hybrid detector with argon-xenon gas mixtures

Monteiro

Veloso

Santos

et al. 2002

IEEE Trans. Nucl. Sci.

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“…Different behaviours are observed for argon and xenon hybrid detectors at high E=p values in the scintillation region when compared to the APD instrumented GPSCs: while for xenon the detector pulse amplitude tends to saturate; for argon, the detector pulse amplitude still increases with E=p; though not as much as it would if only the charge multiplication occurring in the scintillation region above the argon ionisation threshold (B3.7 V cm À1 Torr À1 ) were taken into account (as in the GPSC-APD detectors [14,15]). These differences are due to the decrease of the electric field intensity at the CsI photocathode surface with increasing electric field in the scintillation region [1,16]. The experimental results show that the influence of the electric field intensity at the CsI surface on the photoelectron collection efficiency becomes significant at much lower electric fields in argon than in xenon and that this influence, though smaller, is still noticeable in the argon detector for the operating conditions described in this work.…”

Section: Detector Operational Characteristicsmentioning

confidence: 56%

“…G phe and G pre have been calculated by numerical simulation [16] using Townsend coefficients [21] for both argon and xenon gases at 800 Torr, E=p ¼ 5 V cm À1 Torr À1 , V a ¼ 220 V (for argon) and 360 V (for xenon), and assuming a photoelectron emission uniformly distributed over the photocathode active area. From the simulation results we obtained G phe =G pre ¼ 1:2 and 1.8 for argon and xenon, respectively, and G phe ðXeÞB10ÂG phe ðArÞ: From the experimental results presented in Fig.…”

Section: Light Amplification Gain and Photoelectron Collection Efficimentioning

confidence: 99%

The gas proportional scintillation counter/microstrip gas chamber hybrid detector with argon filling

Monteiro

Veloso

Freitas

et al. 2002

Nuclear Instruments and Methods in Physics Research Section A:

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We present the results of a study of an argon gas proportional scintillation counter instrumented with a CsI-coated microstrip plate placed in the argon envelope. Although the measured light amplification gain and the photoelectron collection efficiency are 70% and 30-40% higher than those obtained in a similar xenon detector, the charge gain achieved in argon for the avalanches produced by the photoelectrons at the microstrip anodes is a factor of ten lower than in xenon. In both cases, these gains are limited by optical positive feedback. The energy resolution achieved for 5.9 keV X-rays was 14.8% compared to 12% in xenon. r

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“…The scintillation produced in the avalanche around the anode strips increases with increasing pressure, since the applied V a is higher for higher pressures. Additionally, the electric field at the photocathode surface increases with decreasing E/p [7,18], resulting in a more efficient photoelectron extraction and collection [7,18]. In addition, as the E/p decreases, the photoelectron paths rise higher above the photocathode plane.…”

Section: Article In Pressmentioning

confidence: 99%

“…In addition, as the E/p decreases, the photoelectron paths rise higher above the photocathode plane. This results in an increase of the solid angle subtended by the cathode strips (the photocathode active area) and, thus, in an increase of the positive photon feedback [18]. Therefore, for pressures above 5 bar, the detector relative amplitudes are normalized to those of 1 bar.…”

Section: Article In Pressmentioning

confidence: 99%

High-pressure operation of a xenon-GPSC/MSGC hybrid detector for hard X-ray spectrometry

Coelho

Veloso

Covita

et al. 2006

Nuclear Instruments and Methods in Physics Research Section A:

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The performance of a high-pressure xenon gas proportional scintillation counter/microstrip gas chamber (GPSC/MSGC) hybrid detector has been investigated for filling pressures from 1 up to 10 bar, for 22-, 30-and 60-keV photons. GPSC/MSGC hybrid detectors are based on a xenon-GPSC instrumented with a CsI-coated microstrip plate photosensor placed directly within the xenon envelope, as a substitute for the photomultiplier tube. This design avoids the constraints due to the use of a quartz scintillation window for GPSC-photosensor coupling, which absorbs a significant amount of scintillation and is a drawback for applications where large detection areas and high filling pressures are needed. The lowest energy resolutions are achieved for 2 bar (5.5% and 3.4%, FWHM, for 22-and 60-keV photons, respectively). Increasing the pressure to the 5-6 bar range, competitive energy resolutions of 7% and 4.5% are still achieved for 22-and 60-keV photons, respectively. This detector could be a compelling alternative in applications where compactness, large detection area, insensitivity to strong magnetic fields, room temperature operation, large signal-to-noise ratio and good energy resolution are important requirements. r

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A comparative study of microstrip plate geometries as UV photosensors with reflective photocathodes: simulation

Cited by 10 publications

References 23 publications

The performance of the GPSC/MSGC hybrid detector with argon-xenon gas mixtures

The performance of the GPSC/MSGC hybrid detector with argon-xenon gas mixtures

The gas proportional scintillation counter/microstrip gas chamber hybrid detector with argon filling

High-pressure operation of a xenon-GPSC/MSGC hybrid detector for hard X-ray spectrometry

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