1,284 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
Tipping the tea table: An argument for reforming an image, from the austere Miss Austen to jolly Aunt Jane
The standard edition of Jane Austen’s novels and other works was edited by R. W. Chapman and published in six volumes by Oxford at the Clarendon Press. The original five volumes were published in 1923, followed by subsequent editions and impressions in 1926, 1933, 1943, 1946 and 1948. The sixth volume, Minor Works, first appeared in 1954
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
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
Modeling of water balance response to an extreme future scenario in the Ă–tztal catchment, Austria
The aim of the study was to investigate the impact of climate change on the
water balance of the Ă–tztaler Ache catchment in Tyrol, Austria. For this
purpose the conceptual hydrological model HBV-D REG was applied. First, the
model was calibrated and validated using current observed climate and
discharge data. Second, the calibrated model was applied with reanalysis
data. Third, downscaled climate scenarios from 2010 to 2099 served as input
data to the HBV-D REG. Thereby two extreme land cover scenarios were
considered: for water balance modeling a constant glacier coverage from today
and additionally for runoff simulations a complete loss of glaciered area.
The downscaled climate data were generated with the expanded downscaling
method. Scenario simulations indicated an increase in annual areal
temperature by 3.4 °C and a slight decrease in annual areal
precipitation by 89 mm in the next one hundred years. According to the hydrological
modeling, these climate changes caused an increase in evapotranspiration and
a decrease in snow coverage. Furthermore model simulations showed an increase
in winter and spring runoff, whereas summer runoff was highly sensitive to
glacier coverage and decreased with complete loss of glacier coverage
The Development and Study of High-Position Resolution (50 micron) RPCs for Imaging X-rays and UV photons
Nowadays, commonly used Resistive Plate Chambers (RPCs) have counting rate
capabilities of ~10E4Hz/cm2 and position resolutions of ~1cm. We have developed
small prototypes of RPCs (5x5 and 10x10cm2) having rate capabilities of up to
10E7Hz/cm2 and position resolutions of 50 micron("on line" without application
of any treatment method like "center of gravity"). The breakthrough in
achieving extraordinary rate and position resolutions was only possible after
solving several serious problems: RPC cleaning and assembling technology,
aging, spurious pulses and afterpulses, discharges in the amplification gap and
along the spacers. High-rate, high-position resolution RPCs can find a wide
range of applications in many different fields, for example in medical imaging.
RPCs with the cathodes coated by CsI photosensitive layer can detect
ultraviolet photons with a position resolution that is better than ~30 micron.
Such detectors can also be used in many applications, for example in the focal
plane of high resolution vacuum spectrographs or as image scanners.Comment: 6 pages, 5 figures, other comment
The Successful Operation of Hole-type Gaseous Detectors at Cryogenic Temperatures
We have demonstrated that hole-type gaseous detectors, GEMs and capillary
plates, can operate up to 77 K. For example, a single capillary plate can
operate at gains of above 10E3 in the entire temperature interval between 300
until 77 K. The same capillary plate combined with CsI photocathodes could
operate perfectly well at gains (depending on gas mixtures) of 100-1000.
Obtained results may open new fields of applications for capillary plates as
detectors of UV light and charge particles at cryogenic temperatures: noble
liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogenic
PETs.Comment: Presented at the IEEE Nuclear Science Symposium, Roma, 200
Study of capillary-based gaseous detectors
We have studied gain vs. voltage characteristics and position resolutions of
multistep capillary plates (two or three capillary plates operating in a
cascade), as well as capillary plates operating in a mode when the main
amplification occurs between plates or between the capillary plate and the
readout plate (parallel plate amplification mode). Results of these studies
demonstrated that in the parallel-plate amplification mode one can reach both
high gains (>100000) and good position resolutions (~100 micro meter) even with
a single step arrangement. It offers a compact amplification structure, which
can be used in many applications. For example, in preliminary tests we
succeeded to combine it with a photocathode and use it as a position sensitive
gaseous photomultiplier. CsI coated capillary plates could also be used as a
high position resolution and high rate X-ray converter.Comment: Presented at the NSS IEEE 2003 conference in Portland, submitted to
TN
“The missing lights of Nairobi”: Cyclists' Perceptions of safety by cycling after-dark in Nairobi, Kenya
Promotion of cycling is important to reach the goals for climate mitigation of the Paris Agreement and Goals ofthe Agenda 2030. Sustainable transport, both rural and urban, could contribute to at least seven of the 17 Sustainable Development Goals (ITDP 2015). There is relatively little research on cycling in Africa, and there is also much less research on cycling at night. Some studies show the importance of road lighting for minimising the reduction in the numbers of cyclists after-dark and suggest 'only a minimal amount of lighting can promote cycling after-dark, making it an attractive mode of transport year-round' (Uttley at el. 2020). So far, these studies have little relation to the
situation in developing countries, which is why a first study in Nairobi, Kenya, is carried out here as an example. ... [From: Introduction
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