2,313 research outputs found
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
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