496 research outputs found
Further developments of the gas electron multiplier (GEM)
No full textWe describe the development and operation of the Gas Electron Multiplier, a thin insulating foil metal-clad on both sides and perforated by a regular pattern of small holes. The mesh can be incorporat ed in the gas volume of an active detector to provide a first amplification channel for electrons, or used as stand alone. We report on the basic properties of GEMs manufactured with different geometr ies and operated in several gas mixtures as well as on their long-term stability after accumulation of charge equivalent to several years of operation in high luminosity experiments. Optimized GEMs re ach gains close to 10000 at safe operating voltages, permitting the detection of ionizing tracks, without other amplifying elements, on a simple printed circuit board (PCB), opening new possibilities for detector design
High rate behavior and discharge limits in micro-pattern detectors
No full textWe present and discuss a set of systematic measurements, carried out with gaseous proportional micro-pattern detectors, in order to assess their maximum gain when irradiated with high-rate soft X-rays and heavily ionizing alpha particles. The inventory of detectors tested includes: micro-strips, micromegas, micro-dot, gas electron multiplier, CAT (compteur a trous), trench (or groove), micro-CAT (or WELL) detectors, as well as systems with two elements of gaseous amplification in cascade. We confirm the general trend of all single-stage detectors to follow Raether's criterion, i.e. a spontaneous transition from avalanche to streamer, followed by a discharge, when the avalanche size reaches a value of a few 107; a noticeable exception is the micro-clot counter holding more than 108. In multiple structures, where the gain is shared between two devices in cascade, the maximum overall gain under irradiation is increased by at least one order of magnitude; we speculate this to be a consequence of a voltage dependence of Raether's limit, larger for low operating potentials. Our conclusion is that only multiple devices can guarantee a sufficient margin of reliability for operation in harsh LHC running conditions.F.I. 1,0910Elsevier, Amsterdaminfo:eu-repo/semantics/publishe
PROGRESS ON HIGH-RESOLUTION TRACKING WITH SCINTILLATING FIBERS - A NEW DETECTOR BASED ON CAPILLARIES FILLED WITH LIQUID SCINTILLATOR
No full textThe capabilities of a new detector based on capillaries filled with liquid scintillator have been investigated. Tests have been performed using various scintillating cocktails and readout systems. With the best combinations, and for light propagation over a few centimetres, the hit density is as high as 5 hits/mm. For propagation over distances greater than 10 cm, an attenuation length of approximately 95 cm is measured. A spatial resolution of sigma congruent-to 12-mu-m is obtained with capillaries of 20-mu-m bore
Progress on high-resolution tracking with scintillating fibres: a new detector based on capillaries filled with liquid scintillator
No full textThe capabilities of a new detector based on capillaries filled with liquid scintillator have been investigated. Tests have been performed using various scintillating cocktails and readout systems. With the best combinations, and for light propagation over a few centimetres, the hit density is as high as 5 hits/mm. For propagation over distances greater than 10 cm, an attenuation length of approximately 95 cm is measured. A spatial resolution of sigma congruent-to 12-mu-m is obtained with capillaries of 20-mu-m bore
Liquid scintillator filled capillary arrays for particle tracking
No full textCoherent arrays of glass capillaries filled with liquid scintillator offer interesting possibilities in high resolution particle tracking. We describe the preparation and filling of capillary targets with 20 and 120-mu-m diameter lightguides, as well as the performance of capillary targets in a 5 GeV test beam exposure. Considerations are given concerning choice and optimization of solvents with high refractive index and fluorescence dyes. Furthermore results of systematic studies of liquid scintillators in beam tests are reported
Charged-particle tracking with high spatial and temporal resolution using capillary arrays filled with liquid scintillator
No full textWe developed a new technique that allows the trajectories of ionizing particles to be imaged with very high spatial and temporal resolution. This technique, developed for future experiments in high-energy physics, may also be applied in other field. Central to the technique is a detector consisting of a bundle of thin, glass capillaries filled with a liquid scintillator of high refractive index. These liquid-core scintillating fibers act simultaneously as a detector of charged particles and as an image guide. Track images seen at the readout end of the capillary bundle are amplified by an optoelectronic chain consisting of a set of image-intensifier tubes and read by a photosensitive CCD camera. We report here on results obtained with detector prototypes. A spatial resolution of 6-14 micrometers , dependent on image magnification prior to readout, has been obtained with 16 micrometers capillaries. The high scintillation efficiency of the liquid scintillator used and a large light attenuation length-- approximately 3 m for 20 micrometers capillaries--result in hit densities along the track of a minimum-ionizing particle of 8.5 mm and 3.5 mm at distances from the readout window of approximately 2 cm and approximately 1 m respectively. The radiation resistance of the detector is an order of magnitude greater than that of other types of tracking device of comparable performance. To complement the detector we have been developing a new readout system based around a gateable vacuum image pipeline (VIP) and an electron- bombarded CCD camera. These increase the spatial and temporal resolution obtained with detector and render it particlarly attractive as a microvertex detector for the observation of short-lived particles in high-energy physics experiments performed with evelated interaction rates
On the Possibility of Measuring FL(x, Q2) at HERA using Radiative Events
No full textinfo:eu-repo/semantics/publishe
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