1,000 research outputs found
Detection of high-energy muons in cosmic ray showers
The DELPHI detector located at LEP accelerator has been used to measure multi-muon bundles originated from cosmic ray interactions. Two subdetectors - Hadron Calorimeter and Time Projection Chamber, are used for this purpose. The 1999 and 2000 data are analyzed over wide range of muon multiplicities. The muon multiplicity distribution is compared with prediction of Monte-Carlo simulation based on CORSIKA/QGSJET. The Monte-Carlo does not describe the large multiplicity part of data. Even the extreme assumption on the cosmic ray composition (pure iron nuclei) hardly predicts number of high multiplicity events comparable with the data. The impact of QGSJET internal parameters onto the result is also studied
Detection of ultra-high energy cosmic ray showers with a single-pixel fluorescence telescope
We present a concept for large-area, low-cost detection of ultra-high energy
cosmic rays (UHECRs) with a Fluorescence detector Array of Single-pixel
Telescopes (FAST), addressing the requirements for the next generation of UHECR
experiments. In the FAST design, a large field of view is covered by a few
pixels at the focal plane of a mirror or Fresnel lens. We report first results
of a FAST prototype installed at the Telescope Array site, consisting of a
single 200 mm photomultiplier tube at the focal plane of a 1 m Fresnel lens
system taken from the prototype of the JEM-EUSO experiment. The FAST prototype
took data for 19 nights, demonstrating remarkable operational stability. We
detected laser shots at distances of several kilometres as well as 16 highly
significant UHECR shower candidates.Comment: Accepted for publication in Astroparticle Physic
The Central Laser Facility at the Pierre Auger Observatory
The Central Laser Facility is located near the middle of the Pierre Auger
Observatory in Argentina. It features a UV laser and optics that direct a beam
of calibrated pulsed light into the sky. Light scattered from this beam
produces tracks in the Auger optical detectors which normally record nitrogen
fluorescence tracks from cosmic ray air showers. The Central Laser Facility
provides a "test beam" to investigate properties of the atmosphere and the
fluorescence detectors. The laser can send light via optical fiber
simultaneously to the nearest surface detector tank for hybrid timing analyses.
We describe the facility and show some examples of its many uses.Comment: 4 pages, 5 figures, submitted to 29th ICRC Pune Indi
(1,2,3,4-Tetrahydroisoquinoline-2-carbodithioato-κ2 S,S′)(thiocyanato-κN)(triphenylphosphane)nickel(II)
The NiII atom in the mononuclear title compound, [Ni(C10H10NS2)(NCS)(C18H15P)], exists within a S2PN donor set that defines a distorted square-planar geometry. A significant asymmetry in the Ni—S bond lengths support the less effective trans effect of SCN− over PPh3
Competition among native and invasive Phragmites australis populations: An experimental test of the effects of invasion status, genome size, and ploidy level
Among the traits whose relevance for plant invasions has recently been suggested are genome size (the amount of nuclear DNA) and ploidy level. So far, research on the role of genome size in invasiveness has been mostly based on indirect evidence by comparing species with different genome sizes, but how karyological traits influence competition at the intraspecific level remains unknown. We addressed these questions in a common-garden experiment evaluating the outcome of direct intraspecific competition among 20 populations of Phragmites australis, represented by clones collected in North America and Europe, and differing in their status (native and invasive), genome size (small and large), and ploidy levels (tetraploid, hexaploid, or octoploid). Each clone was planted in competition with one of the others in all possible combinations with three replicates in 45-L pots. Upon harvest, the identity of 21 shoots sampled per pot was revealed by flow cytometry and DNA analysis. Differences in performance were examined using relative proportions of shoots of each clone, ratios of their aboveground biomass, and relative yield total (RYT). The performance of the clones in competition primarily depended on the clone status (native vs. invasive). Measured in terms of shoot number or aboveground biomass, the strongest signal observed was that North American native clones always lost in competition to the other two groups. In addition, North American native clones were suppressed by European natives to a similar degree as by North American invasives. North American invasive clones had the largest average shoot biomass, but only by a limited, nonsignificant difference due to genome size. There was no effect of ploidy on competition. Since the North American invaders of European origin are able to outcompete the native North American clones, we suggest that their high competitiveness acts as an important driver in the early stages of their invasion
Performance of a small size telescope (SST-1M) camera for gamma-ray astronomy with the Cherenkov Telescope Array
The foreseen implementations of the Small Size Telescopes (SST) in CTA will
provide unique insights into the highest energy gamma rays offering fundamental
means to discover and under- stand the sources populating the Galaxy and our
local neighborhood. Aiming at such a goal, the SST-1M is one of the three
different implementations that are being prototyped and tested for CTA. SST-1M
is a Davies-Cotton single mirror telescope equipped with a unique camera
technology based on SiPMs with demonstrated advantages over classical
photomultipliers in terms of duty-cycle. In this contribution, we describe the
telescope components, the camera, and the trigger and readout system. The
results of the commissioning of the camera using a dedicated test setup are
then presented. The performances of the camera first prototype in terms of
expected trigger rates and trigger efficiencies for different night-sky
background conditions are presented, and the camera response is compared to
end-to-end simulations.Comment: All CTA contributions at arXiv:1709.0348
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