Position Sensitive Gaseous Photomultipliers

Advances in the technologies associated with position sensitive gaseous detectors especially featuring CsI as reflective photoconverters will be reviewed. These photodetectors represent the most effective solution for what concerns cost and performance in the case of large area Cherenkov imaging applications in relatively low rate (or low occupancy) high energy physics and astrophysics experiments. Moreover, they are the only choice when the Cherenkov detector is embedded in a magnetic field. Recently proposed single photon MPGDs (Micropattern Gaseous Detectors) will be also discussed in view of the successful efforts so far made to extend their sensitivity to visible light. With some modifications, photosensitive gaseous detectors can also be used in the imaging of X-rays and particles.Comment: Submitted to the special issue "Photodetectors and Imaging Technologies" of the "Sensors" Journa

Dilogic-2: A Sparse Data Scan Readout Processor for the HMPID Detector of ALICE

The processing of analog information is always spoiled by additional DC level and noise given by the sensors or their additional readout electronics. The Dilogic-2 ASICcircuit has been developed in a 0.7um n-well CMOS technologyto process the data given by Analog to Digital Converters, in order to eliminate the empty channels, to subtract the base line (pedestal) and to locally store the true analog information.(Abstract only available, full text willfollow

Progress in Developing Hybrid RPCs: GEM-like Detectors with Resistive Electrodes

We have recently developed an innovative detector of photons and charged particles: a GEM-like gaseous amplification structure with resistive electrodes instead of commonly used metallic ones. This novel detector combines the best property of GEMs- the capability to operate in a cascaded mode and in poorly quenched gases - and of RPC: the protection against sparks. In this paper will shortly review our latest achievements in this direction, however the main focus will be given on a new advanced design that allows to build large area detectors manufactured by a screen printing technology. The proposed detector, depending on the applications, can operate either in a GEM mode (electron multiplications through holes only) or as a hybrid RPC with simultaneous amplifications in the drift region and in the holes. The possible applications of this new detector will be discussed

Progress in the development of a S RETGEM-based detector for an early forest fire warning system

In this paper we present a prototype of a Strip Resistive Thick GEM photosensitive gaseous detector filled with Ne and ethylferrocene vapours at a total pressure of 1 atm for an early forest fire detection system. Tests show that it is one hundred times more sensitive than the best commercial ultraviolet flame detectors and therefore, it is able to reliably detect a flame of 1.5x1.5x1.5 m3 at a distance of about 1km. An additional and unique feature of this detector is its imaging capability, which in combination with other techniques, may significantly reduce false fire alarms when operating in an automatic mode. Preliminary results conducted with air filled photosensitive gaseous detectors are also presented. The approach main advantages include both the simplicity of manufacturing and affordability of construction materials such as plastics and glues specifically reducing detector production cost. The sensitivity of these air filled detectors at certain conditions may be as high as those filled with Ne and EF. Long term test results of such sealed detectors indicate a significant progress in this direction. We believe that our detectors utilized in addition to other flame and smoke sensors will exceptionally increase the sensitivity of forest fire detection systems. Our future efforts will be focused on attempts to commercialize such detectors utilizing our aforementioned findings.Comment: Presented at the International Conference on Micropattern gaseous detectors, Crete, Greece, June 200

Performance of wire-type Rn detectors operated with gas gain in ambient air in view of its possible application to early earthquake predictions

We describe a detector of alpha particles based on wire type counters (single-wire and multiwire) operating in ambient air at high gas gains (100-1000). The main advantages of these detectors are: low cost, robustness and ability to operate in humid air. The minimum detectable activity achieved with the multiwire detector for an integration time of 1 min is 140 Bq per m3, which is comparable to that featured by commercial devices. Owing to such features the detector is suited for massive application, for example for continuous monitoring of Rn or Po contaminations or, as discussed in the paper, its use in a network of Rn counters in areas affected by earth-quakes in order to verify, on a solid statistical basis, the envisaged correlation between the sudden Rn appearance and a forthcoming earthquake

Advances in the Development of Micropattern Gaseous Detectors with Resistive Electrodes

We describe the most recent efforts made by various groups in implementing resistive electrodes in micropattern gaseous detectors with the aim to combine in the same design the best features of RPCs (for the example, their robustness and spark protection property) with the high granularity and thus the good position resolution offered by microelectronic technology. In the stream of this activity, we have recently developed two novel detectors with resistive electrodes: one was based on resistive micromeshes and the second one is a MSGC with resistive electrodes. We have demonstrated that the resistive meshes are a convenient construction element for various designs of spark protective detectors: RPCs type, GEM type and MICROMEGAS type. These new detectors enable to considerably enhance the RPC and micropattern detectors applications since they feature not only a high position resolution but also a relatively good energy resolution (25-30 persent FWHM at 6 keV) and, if necessary, they can operate in cascaded mode allowing the achievement of a high overall gas gain. The main conclusion from these studies is that the implementation of resistive electrodes in micropattern detectors makes them fully spark protected; on this basis we consider this direction very promising

New designs of resistive microstrip gaseous detectors (R-MSGCs)

A new family of spark-protected micropattern gaseous detectors is introduced: a 2-D sensitive restive microstrip counter and hybrid detectors, which combine in one design a resistive GEM with a microstrip detector. These novel detectors have several important advantages over other conventional micropattern detectors and are unique for applications like the readout detectors for dual phase noble liquid TPCs and RICHs

First observation of Cherenkov rings with a large area CsI-TGEM-based RICH prototype

We have built a RICH detector prototype consisting of a liquid C6F14 radiator and six triple Thick Gaseous Electron Multipliers (TGEMs), each of them having an active area of 10x10 cm2. One triple TGEM has been placed behind the liquid radiator in order to detect the beam particles, whereas the other five have been positioned around the central one at a distance to collect the Cherenkov photons. The upstream electrode of each of the TGEM stacks has been coated with a 0.4 micron thick CsI layer. In this paper, we will present the results from a series of laboratory tests with this prototype carried out using UV light, 6 keV photons from 55Fe and electrons from 90Sr as well as recent results of tests with a beam of charged pions where for the first time Cherenkov Ring images have been successfully recorded with TGEM photodetectors. The achieved results prove the feasibility of building a large area Cherenkov detector consisting of a matrix of TGEMs.Comment: Presented at the International Conference NDIP-11, Lyon,July201

Morte e rinascita del mito : un’ipotesi filosofica

Come si pu\uf2 pensare il mito non in quanto espressione di una fase superata della storia umana, ma come manifestazione di una razionalit\ue0 altra, che non si riduce a quella del pensare per concetti? Questo contributo traccia un percorso che affronta il problema della produzione narrativa e mitica, connettendola alla questione del simbolico e dell\u2019immaginazione: la via aperta dalla Critica del Giudizio kantiana sfocia nella filosofia dei simboli di Paul Ricoeur, enfatizzando cos\uec il ruolo dell\u2019immagine nella produzione del mito. In questo senso, il mito e l\u2019immagine hanno in comune la stessa caratteristica di fondo: la loro origine nelle esperienze pi\uf9 originarie e profonde dell\u2019uomo, innanzitutto quella della morte, cio\ue8 del venir meno della presenza del s\ue9 vivente. L\u2019approccio proposto, all\u2019incrocio tra la filosofia e le scienze sociali (e tra queste soprattutto l\u2019antropologia), cerca di esibire l\u2019inesauribilit\ue0 del potenziale immaginativo del mito, nonch\ue9 la necessit\ue0 della sua riscrittura.Comment peut-on penser le mythe non en tant qu\u2019expression d\u2019une phase d\ue9pass\ue9e de l\u2019histoire, mais en tant que manifestation d\u2019une rationalit\ue9 autre, qui ne se r\ue9duit pas \ue0 la pens\ue9e conceptuelle ? Cette contribution trace un parcours qui face le probl\ue8me de la production narrative et mythique, li\ue9e \ue0 la question du symbolique et de l\u2019imagination : la voie ouverte par la Critique du jugement kantienne aboutit dans la philosophie des symboles de Paul Ricoeur, soulignant le r\uf4le de l\u2019image dans la production du mythe. En ce sens, mythe et image manifestent la m\ueame caract\ue9ristique fondamentale : leur d\ue9rivation des exp\ue9riences les plus originaires et profondes de l\u2019humain, avant tout celle de la mort, c\u2019est \ue0 dire de la disparition de la pr\ue9sence donn\ue9e du soi vivant. L\u2019approche propos\ue9e, \ue0 l\u2019entrecroisement de la philosophie avec les sciences sociales et notamment l\u2019anthropologie, vise \ue0 montrer l\u2019in\ue9puisabilit\ue9 du potentiel imaginatif du mythe, ainsi que la \uab n\ue9cessit\ue9 \ubb de sa r\ue9\ue9criture

Photosensitive Strip RETHGEM

An innovative photosensitive gaseous detector, consisting of a GEM like amplification structure with double layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen printing technology on the top of the metallic strips grid The inner metallic grid is used for 2D position measurements whereas the resistive layer provides an efficient spark protected operation at high gains - close to the breakdown limit. Detectors with active areas of 10cm x10cm and 10cm x20cm were tested under various conditions including the operation in photosensitive gas mixtures containing ethylferrocene or TMAE vapors. The new technique could have many applications requiring robust and reliable large area detectors for UV visualization, as for example, in Cherenkov imaging devices.Comment: Presentes at the International Conference NDIP 2008, July 2008, Franc