Active Area Of Detector Research Articles

A fast large-area position-sensitive time-of-flight neutron detection system

A novel position-sensitive time-of-flight neutron detection and histograming system has been developed for use at the Intense Pulsed Neutron Source. Spatial resolution of roughly 1 cm*1 cm and time-of-flight resolution of approximately 1 mu s are combined in a detection system which can ultimately be expanded to cover several square meters of active detector area. This system is based on the use of arrays of cylindrical one-dimensional position-sensitive proportional counters and is capable of collecting the x-y-t data and sorting them into histograms at time-averaged data rates up to approximately 300000 events/s over the full detector area and with instantaneous data rates up to more than 50 times that. Numerous hardware features have been incorporated to facilitate initial tuning of the position encoding, absolute calibration of the encoded positions, and automatic testing for drifts.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A gridless position sensitive time-zero detector for heavy ions

A position sensitive time-zero detector (active area 19×49 mm 2) for the magnetically focussng heavy-ion time-of-flight spectrometer [1] at GSI is described. The detection of the heavy ions is based on secondary electrons expelled from a thin carbon foil (20−30 μg/cm 2) and deflected onto a channel-plate with position readout. Using orthogonal electric and magnetic fields for the electron deflection, the heavy-ion flight-path is kept free from wire grids that would decrease the detector transmission and would cause an energy loss for a fraction of the passing ions. Test measurements with heavy ions ( 84Kr, 238U) resulted in a time resolution of 100–130 ps (fwhm), a position resolution of 0.8–0.9 mm (fwhm), and an efficiency of 90–100%. For α-particles the corresponding values are 175 ps, 0.5 mm, and 80%. With off-line corrections the time resolution could be improved to 90 ps for heavy ions and 140 ps for α-particles.

An attempt to restrict the active area of a silicon surface barrier detector

Reports work which was carried out with the intention of making a semiconductor particle radiation detector with a small active volume. A study of the detector was made using a narrow collimated beam of alpha particles. The results, which showed that the authors' expectations were not fulfilled, can be explained qualitatively in terms of the electric field in the device.

Spectrum and Galactic Isotropy of Diffuse Cosmic X-rays

ON February 29, 1968, we surveyed the X-ray emission from the general direction of the galactic centre. The detector was a 2 mm thick NaI(Tl) crystal, surrounded by a well of NaI(Tl) with a 1-inch thick CsI(Na) crystal acting as a collimator. The latter crystal had an array of sixty-five holes, each 1 cm in diameter, drilled through it, leading to an active detector area of 54 cm2 and a field of view of 8.9° (full width at half maximum). The geometric factor was 1.36 cm2 sr for a diffuse source and 8.44 cm2 rad for a line source.

The shape of pulses generated by alpha-particles in silicon drifted detectors

The paper presents the results of investigations of the shape of an ses generated by α-particles in silicon drifted detectors having an active area 0.7 to 2.4 mm thick, under room and liquid nitrogen temperatures. It has been found, by fitting the analytical form of the pulse to an experimental shape, that the electric field distribution in such a detector is a parabolic function of depth. The distribution of concentration of donor impurities has been determined. Pulse risetimes have been determined as a function of the average value of the electric field and the thickness of the detector active area. Some information has also been obtained about the influence of short-term trapping on the process of charge collection.