Gas proportional scintillation counter pulse-signature analysis using digital techniques

The use of short shaping time-constants (50 ns) followed by digital sampling of gas proportional scintillation counter pulses is investigated. Such short shaping time causes each pulse to closely resemble the scintillation light burst, allowing for an effective pulse-signature analysis. Pulse amplitude is obtained by numerical integration of the digital pulse samples. The shorter total pulse durations, lead to pulse-height distributions that are much less dependent on the total interaction rate occurring in the detector. Total interaction rates up to 12 k s-1 can be tolerated without significant degradation of the obtained pulse-height distribution. It was also verified that the maximum throughput achieved by the digital pulse-height analyser improves from 1 to 1.7 k s-1 when using the short shaping time-constants.http://www.sciencedirect.com/science/article/B6TJM-3VR1CVW-2F/1/2e9e952e1c3752048a2954b0dbbdec2

A new method for pulse analysis of driftless-gas proportional scintillation counters

A new method for pulse analysis of driftless-gas proportional scintillation counters (GPSCs) is presented. With this method the requirement for additional analog or digital signal time-analysis and pulse-amplitude correction currently used is eliminated. In contrast to conventional- and driftless-GPSCs that have always relied on long shaping-time constants (several [mu]s), the use of very short linear amplifier shaping-time constants (~50 ns) enables pulse shapes to closely represent the scintillation light-pulse time-profile. Since the number of detected photons in the photosensor increases continuously with depth due to the increase in the solid angle subtended by the photosensor, a maximum is achieved when the primary electron cloud is closest to the anode. This maximum depends only on the number of primary electrons in that cloud, regardless of where the X-ray absorption took place, and is proportional to the X-ray energy.http://www.sciencedirect.com/science/article/B6TJM-486BN6Y-1C/1/d4c285545f4a2f1fb3da56268ff8df9

The X-ray performance of a driftless gas proportional scintillation counter using short shaping-time constants for pulse analysis

Performance characteristics are evaluated for a xenon driftless gas proportional scintillation counter (GPSC), for which detector pulses are formatted using very short shaping-time constants (~50 ns), and directly analyzed by the MCA without previous pulse time duration analysis and amplitude correction. The present detector and method allow the achievement of detector energy linearity and energy resolution similar to those of conventional GPSCs, reducing background levels and maximizing the detector count-rate capability. However, the obtained peak tails can be somewhat larger than those obtained with conventional GPSCs for X-ray energies above ~30 keV. Energy resolutions of 7.7%, 4.5% and 3.8% can be achieved for 5.9, 22.1 and 59.6 keV X-rays, respectively.http://www.sciencedirect.com/science/article/B6TJM-4BRJ561-J/1/7e1da2da1ab9696753720d39add33d5

Energy non-linearity effects in argon gaseous detectors in the region of the Ar K-absorption edge: experimental results

The response of an argon proportional counter to X-rays with energy in the range of 1.5-8 keV was investigated. The response to full-energy absorption events was found to follow different trends for X-ray energies below and above the argon K-absorption edge presenting a discontinuity at this energy. An abrupt decrease of (2.2±0.3)% in the detector amplitude at the K-edge (3.203 keV) was measured, corresponding to a region within±(70±10) eV around the edge where the X-ray energy cannot be obtained unambiguously. This discontinuity corresponds to an abrupt increase of about 0.5 eV in the argon w-value and results in a sudden increase in the energy resolution from about 17% to about 19%. The detector response to escape peak events follows a linear trend over the entire energy range, very close to the response for full-energy absorption of X-rays with energies above the K-edge.http://www.sciencedirect.com/science/article/B6TJM-488X1RS-1/1/73262067a3d0d1b1648af14b65285c5