51 research outputs found
Novel Single Photon Detectors for UV Imaging
There are several applications which require high position resolution UV
imaging. For these applications we have developed and successfully tested a new
version of a 2D UV single photon imaging detector based on a microgap RPC. The
main features of such a detectors is the high position resolution - 30 micron
in digital form and the high quantum efficiency (1-8% in the spectral interval
of 220-140 nm). Additionally, they are spark- protected and can operate without
any feedback problems at high gains, close to a streamer mode. In attempts to
extend the sensitivity of RPCs to longer wavelengths we have successfully
tested the operation of the first sealed parallel-plate gaseous detectors with
CsTe photocathodes. Finally, the comparison with other types of photosensitive
detectors is given and possible fields of applications are identified.Comment: Presented at the 5th International Workshop on RICH detectors Playa
del Carmen, Mexico, November 200
Beyond the RICH: Innovative Photosensitive Gaseous Detectors for new Fields of Applications
We have developed and successfully used several innovative designs of
detectors with solid photocathodes. The main advantage of these detectors is
that rather high gains (>10E4) can be achieved in a single multiplication step.
This is possible by, for instance, exploiting the secondary electron
multiplication and limiting the energy of the steamers by distributed
resistivity. The single step approach also allows a very good position
resolution to be achieved in some devices: 50 micron on line without applying
any treatment method (like center of gravity). The main focus of our report is
new fields of applications for these detectors and the optimization of their
designs for such purposes.Comment: 14 pages, 7 figures, 3 table
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
Design, Construction, Operation and Performance of a Hadron Blind Detector for the PHENIX Experiment
A Hadron Blind Detector (HBD) has been developed, constructed and
successfully operated within the PHENIX detector at RHIC. The HBD is a
Cherenkov detector operated with pure CF4. It has a 50 cm long radiator
directly coupled in a window- less configuration to a readout element
consisting of a triple GEM stack, with a CsI photocathode evaporated on the top
surface of the top GEM and pad readout at the bottom of the stack. This paper
gives a comprehensive account of the construction, operation and in-beam
performance of the detector.Comment: 51 pages, 39 Figures, submitted to Nuclear Instruments and Method
Aging in gaseous photodetectors
This paper describes the present status of the aging studies in various
photosensitive detectors. New experimental data are presented on aging of
trimethilamine (TMA) and ethilferrocene (EF) photosensitive vapors as well as
on CsI and SbCs photocathodes. A new explanation of the CsI photocathodes aging
process based on solid state physics theory is given. Finally, based on our
studies, a general conclusion was made that thin polymer depositions on the
detector=92s cathode due to the aging can provoke breakdowns through the
Malter-type mechanism (or more precisely- an explosive field emission
mechanism).Comment: 25 pages in pdf forma
The HERMES Dual-Radiator Ring Imaging Cerenkov Detector
The construction and use of a dual radiator Ring Imaging Cerenkov(RICH)
detector is described. This instrument was developed for the HERMES experiment
at DESY which emphasizes measurements of semi-inclusive deep-inelastic
scattering. It provides particle identification for pions, kaons, and protons
in the momentum range from 2 to 15 GeV, which is essential to these studies.
The instrument uses two radiators, C4F10, a heavy fluorocarbon gas, and a wall
of silica aerogel tiles. The use of aerogel in a RICH detector has only
recently become possible with the development of clear, large homogeneous and
hydrophobic aerogel. A lightweight mirror was constructed using a newly
perfected technique to make resin-coated carbon-fiber surfaces of optical
quality. The photon detector consists of 1934 photomultiplier tubes for each
detector half, held in a soft steel matrix to provide shielding against the
residual field of the main spectrometer magnet.Comment: 25 pages, 23 figure
Model Independent Determination of the Solar Neutrino Spectrum with and without MSW
Besides the opportunity for discovering new neutrino physics, solar neutrino
measurements provide a sensitive probe of the solar interior, and thus a
rigorous test of solar model predictions. We present model independent
determinations of the neutrino spectrum by using relevant flux components as
free parameters subject only to the luminosity constraint. (1) Without the
Mikheyev-Smirnov-Wolfenstein (MSW) effect, the best fit for the combined data
is poor. Furthermore, the data indicate a severe suppression of the Be flux
relative to the B, contradicting both standard and nonstandard solar models
in general; the flux takes its maximum value allowed by the luminosity
constraint. This pathology consistently appears even if we ignore any one of
the three data. (2) In the presence of the two-flavor MSW effect, the current
constraint on the initial B flux is weak, but consistent with the SSM and
sufficient to exclude nonstandard models with small B fluxes. No meaningful
constraint is obtained for the other fluxes. In the future, even allowing MSW,
the B and Be fluxes can be determined at the (15 -- 20)\% level,
making competing solar models distinguishable. We emphasize that the neutral
current sensitivity for Be neutrinos in BOREXINO, HELLAZ, and HERON is
essential for determining the initial fluxes. The constraints on the MSW
parameters in the model independent analysis are also discussed.Comment: Revtex 3.0, 61 pages including 23 figures, uuencoded ps file
attached. Easy way: compressed ps file of entire paper in landscape format
available by anonymous
ftp://upenn5.hep.upenn.edu/pub/hata/papers/model_ind.ps.
Preliminary results of the study of gaseous detectors with solid photocathodes sensitive in the spectral region from 105 to 300 nm
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