An elastic lidar system for the H.E.S.S. Experiment Bregeon, J.; Compin, M.; Rivoire, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2016, Letnik:
819
Journal Article
Recenzirano
Odprti dostop
The H.E.S.S. experiment in Namibia, Africa, is a high energy gamma ray telescope sensitive in the energy range from ~100Gev to a few tens of TeV, via the use of the atmospheric Cherenkov technique. ...To minimize the systematic errors on the derived fluxes of the measured sources, one has to calculate the impact of the atmospheric properties, in particular the extinction parameter of the Cherenkov light (~300–650nm) exploited to observe and reconstruct atmospheric particle showers initiated by gamma-ray photons. A lidar can provide this kind of information for some given wavelengths within this range. In this paper we report on the hardware components, operation and data acquisition of such a system installed at the H.E.S.S. site.
Power consumption and energy efficiency are important factors in the initial design and day-to-day management of computer systems. Researchers and system designers need benchmarks that characterize ...energy efficiency to evaluate systems and identify promising new technologies. To predict the effects of new designs and configurations, they also need accurate methods of modeling power consumption.
Measurement of performance of the NectarCAM photodetectors Tsiahina, A.; Jean, P.; Olive, J.-F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2021, Letnik:
1007
Journal Article
Recenzirano
Odprti dostop
NectarCAM is a camera for the medium-sized telescopes of the Cherenkov Telescope Array (CTA), which covers the energy range of 100 GeV to 30 TeV. The camera is equipped with 265 focal plane modules ...(FPMs). Each FPM comprises 7 pixels, each consisting of a photo-multiplier tube, a preamplifier, an independently controlled power supply, and a common control system. We developed a dedicated test bench to validate and qualify the industrial FPM production and to measure the performance of each FPM in a dark room before its integration in the camera. We report the measured performance of 61 FPM prototypes obtained with our experimental setup. We demonstrate that the gains of the photo multiplier tubes are stable and that pulse widths, transit time spreads, afterpulse rates and charge resolutions are within the specifications for NectarCAM.
The KM3NeT research infrastructure is under construction in the Mediterranean Sea. It consists of two water Cherenkov neutrino detectors, ARCA and ORCA, aimed at neutrino astrophysics and oscillation ...research, respectively. Instrumenting a large volume of sea water with Formula omitted optical modules comprising a total of Formula omitted photomultiplier tubes, KM3NeT will achieve sensitivity to Formula omitted neutrinos from Galactic and near-Galactic core-collapse supernovae through the observation of coincident hits in photomultipliers above the background. In this paper, the sensitivity of KM3NeT to a supernova explosion is estimated from detailed analyses of background data from the first KM3NeT detection units and simulations of the neutrino signal. The KM3NeT observational horizon (for a Formula omitted discovery) covers essentially the Milky-Way and for the most optimistic model, extends to the Small Magellanic Cloud ( Formula omitted). Detailed studies of the time profile of the neutrino signal allow assessment of the KM3NeT capability to determine the arrival time of the neutrino burst with a few milliseconds precision for sources up to 5-8 kpc away, and detecting the peculiar signature of the standing accretion shock instability if the core-collapse supernova explosion happens closer than 3-5 kpc, depending on the progenitor mass. KM3NeT's capability to measure the neutrino flux spectral parameters is also presented.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
► Chemical irritants increase intracellular calcium. ► Intracellular calcium increase may be a biomarker of skin irritation. ► The irritant heptylamine induces ATP release by keratinocytes. ► ATP ...acts as an autocrine stimulus on keratinocyte. ► Analyse of the keratinocyte contribution to chemical stimuli detection.
Intracellular Ca2+ increase is a common feature of multiple cellular pathways associated with receptor and channel activation, mediator secretion and gene regulation. We investigated the possibility of using this Ca2+ signal as a biomarker for a reaction to chemical irritants of normal human keratinocytes (NHK) in submerged primary cell culture. We tested 14 referenced chemical compounds classified as strong (seven), weak (four) or non- (three) irritants in acute irritant contact dermatitis. We found that the strong irritant compounds tested at 20–40mM induced an intracellular Ca2+ increase measurable by spectrofluorimetry in an automated test. Weak and non-irritant compounds however did not increase intracellular Ca2+ concentration. We further investigated the mechanisms by which the amine heptylamine, classified as a R34 corrosive compound, increases intracellular Ca2+. Heptylamine (20mM) induced an ATP release that persisted in the absence of intra- and extra-cellular Ca2+. In addition, we found that this ATP activates NHK purinergic receptors that subsequently cause the increase in intracellular Ca2+ from sarcoplasmic reticular stores. We conclude that measuring the intracellular Ca2+ concentration in NHK is a suitable and easy way of determining any potential reaction to soluble chemical compounds.
PDF
