1,806 research outputs found
Additives That Prevent Or Reverse Cathode Aging In Drift Chambers With Helium-Isobutane Gas
Noise and Malter breakdown have been studied at high rates in a test chamber
having the same cell structure and gas as in the BaBar drift chamber. The
chamber was first damaged by exposing it to a high source level at an elevated
high voltage, until its operating current at normal voltages was below
0.5nA/cm. Additives such as water or alcohol allowed the damaged chamber to
operate at 25 nA/cm, but when the additive was removed the operating point
reverted to the original low value. However with 0.02% to 0.05% oxygen or 5%
carbon dioxide the chamber could operate at more than 25 nA/cm, and continued
to operate at this level even after the additive was removed. This shows for
the first time that running with an O2 or CO2 additive at high ionisation
levels can cure a damaged chamber from breakdown problems.Comment: There were typos: 0.2%-0.5% oxygen should be 0.02%-0.05% oxygen.
Values in the Table were O
Off line Parallax Correction for Neutral Particle Gas Detectors
In a neutral particle gas detector, the parallax error resulting from the
perpendicular projection on the detection plane or wire of the radial particle
trajectories emanating from a point like source (such as a scattering sample)
can significantly spoil the apparent angular resolution of the detector.
However, as we will show, the information is not lost. We propose an off line
data treatment to restore as much as possible the original scattering
information in the case of a one-dimensional parallax effect. The reversibility
of parallax follows from the algebraic structure of this effect, which is
different from the resolution loss which is essentially irreversible. The
interplay between finite resolution and parallax complicates the issue, but
this can be resolved
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
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
Book Review: Politics and health updated
Book Review: Politics and health update
About Detecting CP-Violating Processes in J/\psi\to \KzKzb Decay
Questions about detecting CP-violating decay process of are discussed. Possible background and material
regeneration effect are analyzed. The discussion can be directly extended to
other vector quarkonium decays, like , and .Comment: 5 pages, 2 figures, Late
‘Kangaroo mother care’ to prevent neonatal deaths due to preterm birth complications
Background ‘Kangaroo mother care’ (KMC) includes thermal care through continuous skin-to-skin contact, support for exclusive breastfeeding or other appropriate feeding, and early recognition/response to illness. Whilst increasingly accepted in both high- and low-income countries, a Cochrane review (2003) did not find evidence of KMC’s mortality benefit, and did not report neonatal-specific data
Micromegas in a Bulk
In this paper we present a novel way to manufacture the bulk Micromegas
detector. A simple process based on the PCB (Printed Circuit Board) technology
is employed to produce the entire sensitive detector. Such fabrication process
could be extended to very large area detectors made by the industry. The low
cost fabrication together with the robustness of the electrode materials will
make it extremely attractive for several applications ranging from particle
physics and astrophysics to medicineComment: 6 pages, 4 figure
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
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