Experimental results on gamma-ray sources at E sub 0 = 10(13) - 10(14) eV

The detection of very high energy gamma ray sources has been reported in the last few years by means of extensive air shower observations. The Plateau Rosa array for the registration of the arrival directions of extensive air showers has been operating since 1980 and first results on Cygnus X-3 have been reported. Here, the status of observations of Cygnus X-3 and of the Crab Pulsar are reported

The angular resolution of air shower gamma ray telescopes

A crucial charactristic of air shower arrays in the field of high energy gamma-ray astronomy is their angular resolving power, the arrival directions being obtained by the time of flight measurements. A small air shower array-telescope is used to study the resolution in the definition of the shower front as a function of the shower size

A Study of the Operation of Especially Designed Photosensitive Gaseous Detectors at Cryogenic Temperatures

In some experiments and applications there is need for large-area photosensitive detectors to operate at cryogenic temperatures. Nowadays, vacuum PMs are usually used for this purpose. We have developed special designs of planar photosensitive gaseous detectors able to operate at cryogenic temperatures. Such detectors are much cheaper PMs and are almost insensitive to magnetic fields. Results of systematic measurements of their quantum efficiencies, the maximum achievable gains and long-term stabilities will be presented. The successful operation of these detectors open realistic possibilities in replacing PMs by photosensitive gaseous detectors in some applications dealing with cryogenic liquids; for example in experiments using noble liquid TPCs or noble liquid scintillating calorimeters.Comment: Submitted to the Nuclear Instruments and Method

A concise review on THGEM detectors

We briefly review the concept and properties of the Thick GEM (THGEM); it is a robust, high-gain gaseous electron multiplier, manufactured economically by standard printed-circuit drilling and etching technology. Its operation and structure resemble that of GEMs but with 5 to 20-fold expanded dimensions. The millimeter-scale hole-size results in good electron transport and in large avalanche-multiplication factors, e.g. reaching 10^7 in double-THGEM cascaded single-photoelectron detectors. The multiplier's material, parameters and shape can be application-tailored; it can operate practically in any counting gas, including noble gases, over a pressure range spanning from 1 mbar to several bars; its operation at cryogenic (LAr) conditions was recently demonstrated. The high gain, sub-millimeter spatial resolution, high counting-rate capability, good timing properties and the possibility of industrial production capability of large-area robust detectors, pave ways towards a broad spectrum of potential applications; some are discussed here in brief.Comment: 8 pages, 11 figures; Invited Review at INSTR08, Novosibirsk, Feb 28-March 5 200

The Development of Sealed UV Sensitive Gaseous Detectors and their Applications

We have developed commercial prototypes of sealed gaseous detectors combined with CsI photocathodes and/or filled with photosensitive vapors. The rirst results of application of these devices for the detection of flames in daylight conditions and for the detection of scintillation lights from noble liquids will be presented. The main conclusion from our studies is that for some applications the sealed UV sensitive gaseous detectors have superior performance (higher practical quantum efficiency and better signal to noise ratio) than existing commercial UV sensitive detectors. Additionally, they are much cheaper.Comment: Presented at the Pisa Meeting "Frontier Detectors for Frontier Physics", May 200

Photosensitive Gaseous Detectors for Cryogenic Temperature Applications

There are several proposals and projects today for building LXe Time Projection Chambers (TPCs) for dark matter search. An important element of these TPCs are the photomultipliers operating either inside LXe or in vapors above the liquid. We have recently demonstrated that photosensitive gaseous detectors (wire type and hole-type) can operate perfectly well until temperatures of LN2. In this paper results of systematic studies of operation of the photosensitive version of these detectors (combined with reflective or semi-transparent CsI photocathodes) in the temperature interval of 300-150 K are presented. In particular, it was demonstrated that both sealed and flushed by a gas detectors could operate at a quite stable fashion in a year/time scale. Obtained results, in particular the long-term stability of photosensitive gaseous detectors, strongly indicate that they can be cheap and simple alternatives to photomultipliers or avalanche solid-state detectors in LXe TPC applications.Comment: Submitted to the Proceedings of the PSD-7 Conf. in Liverpool, U

Detection of the primary scintillation light from dense Ar, Kr and Xe with novel photosensitive gaseous detectors

The detection of primary scintillation light in combination with the charge or secondary scintillation signals is an efficient technique to determine the events t=0 as well as particle / photon separation in large mass TPC detectors filled with noble gases and/or condensed noble gases. The aim of this work is to demonstrate that costly photo-multipliers could be replaced by cheap novel photosensitive gaseous detectors: wire counters, GEMs or glass capillary tubes coupled with CsI photocathodes. We have performed systematic measurements with Ar, Kr and Xe gas at pressures in the range of 1-50 atm as well as some preliminary measurements with liquid Xe and liquid Ar. With the gaseous detectors we succeeded in detecting scintillation light produced by 22 keV X-rays with an efficiency of close to 100%. We also detected the scintillation light produced by bs (5 keV deposit energy) with an efficiency close to 25%. Successful detection of scintillation from 22 keV gammas open new experimental possibilities not only for nTOF and ICARUS experiments, but also in others, like WIMPs search through nuclear recoil emission

Development of innovative micropattern gaseous detectors with resistive electrodes and first results of their applications

The paper summarizes our latest progress in the development of newly introduced micro pattern gaseous detectors with resistive electrodes. These resistive electrodes protect the detector and the front-end electronics in case of occasional discharges and thus make the detectors very robust and reliable in operation. As an example, we describe in greater detail a new recently developed GEM-like detector, fully spark-protected with electrodes made of resistive kapton. We discovered that all resistive layers used in these studies (including kapton), that are coated with photosensitive layers, such as CsI, can be used as efficient photo cathodes for detectors operating in a pulse counting mode. We describe the first applications of such detectors combined with CsI or SbCs photo cathodes for the detection of UV photons at room and cryogenic temperatures.Comment: Presented at the 11 Vienna Conference on Instrumentation, February, 200

A Novel UV Photon Detector with Resistive Electrodes

In this study we present first results from a new detector of UV photons: a thick gaseous electron multiplier (GEM) with resistive electrodes, combined with CsI or CsTe/CsI photocathodes. The hole type structure considerably suppresses the photon and ion feedback, whereas the resistive electrodes protect the detector and the readout electronics from damage by any eventual discharges. This device reaches higher gains than a previously developed photosensitive RPC and could be used not only for the imaging of UV sources, flames or Cherenkov light, for example, but also for the detection of X-rays and charged particles.Comment: Presented at the International Workshop on Resistive Plate Chambers, Korea, October 200