The Pierre Auger Observatory: Results and open issues Martello, D.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2014, Letnik:
742
Journal Article
Recenzirano
We will present the status and the main results of the Pierre Auger Observatory. These include the measurement of the cosmic ray energy spectrum above 1018eV, where we observe a suppression for ...energies larger than 5.5×1019eV, the analyses of the arrival directions and the chemical composition. The implications on the origin and on the acceleration mechanisms of the most energetic cosmic rays will be discussed with a particular emphasis to the still open issues.
Suspensions of ZnO nanoparticles in water were prepared with the two-step powder dispersion process using several methods of ultrasonication. The dispersion of ZnO was found to proceed by a ...fragmentation process, with minimum achievable particle size in the range 50 to 300 nm. This is consistent with other oxide nanopowder systems, in which most primary particulates still remain in hardened aggregates that cannot be further reduced. A submersible accelerometer probe was developed and used to measure the relative ultrasonic energy field in the liquid for the various ultrasonication methods. Oscillation at the expected frequencies was identified in each case, with strong variability at different locations in the liquid volume.
Suspensions of ZnO nanoparticles in water were prepared with the two-step powder dispersion process using several methods of ultrasonication. The dispersion of ZnO was found to proceed by a fragmentation process, with minimum achievable particle size in the range 50 to 300 nm. A submersible accelerometer probe was developed and used to measure the relative ultrasonic energy field in the liquid for the various ultrasonication methods.
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In the present paper we show that extracts from
Aegle marmelos Correa are able to inhibit the
in vitro proliferation of human tumor cell lines, including the leukemic K562, T-lymphoid Jurkat, ...B-lymphoid Raji, erythroleukemic HEL, melanoma Colo38, and breast cancer MCF7 and MDA-MB-231 cell lines. Molecules present within the studied
Aegle marmelos C. extracts were identified by gas-chromatography/mass-spectrometry analysis; three derivatives (butyl p-tolyl sulfide, 6-methyl-4-chromanone and butylated hydroxyanisole) were found to exhibit strong activity in inhibiting
in vitro cell growth of human K562 cells. The antiproliferative activity of these compounds was found to be comparable to that of known antitumor agents, including cisplatin, chromomycin, cytosine arabinoside and 5-fluorouracil. In addition, the antiproliferative activity of butyl-p-tolyl sulfide, 6-methyl-4-chromanone and 5-methoxypsolaren was associated to activation of the differentiation pattern of K562 cells.
The ARGO-YBJ experiment is an air shower detector for gamma ray astronomy and cosmic ray studies with an energy threshold of ∼500 GeV. Working in “single particle mode”, i.e. counting the single ...particles hitting the detector at fixed time intervals, ARGO-YBJ can monitor cosmic ray and gamma ray transients at energies of a few GeV.
The single particle counting rate is modulated by the atmospheric pressure and temperature, and is affected by the local radioactivity from soil and air. Among the radioactive elements, radon gas is of particular importance since its concentration in air can vary significantly, according to environmental conditions. In this paper we evaluate the contribution of the radon daughter gamma ray emitters to the single particle counting rate measured by ARGO-YBJ. According to our analysis, the radon gas contribution is roughly 1–2%, producing a counting rate modulation of the same order of magnitude of the atmospheric effects.
•The ARGO-YBJ experiment is an air shower detector for gamma ray astronomy of very large area.•The ARGO-YBJ detector can work into two modes: single particle mode and shower mode.•The work shows how natural radioactivity can influence the single particle counting.•The paper shows how to evidence (and correct) the radon influence on the detector counting.
Measurements of electron, muon and hadron lateral distributions of extensive air showers as recorded in the Karlsruhe shower core and array detector experiment are presented. The data cover the ...energy range from 5×10
14 eV up to almost 10
17 eV and extend from the inner core region to distances of 200 m. The electron and muon distributions are corrected for mutual contaminations by taking into account the detector properties in the experiment. All distributions are well described by NKG functions. The scale radii describing the electron and hadron data best are ≃30 and ≃10 m, respectively. We discuss the correlation between the scale radii and the `age' parameter as well as their dependence on shower size, zenith angle, and particle energy threshold.
Laponite, Fe
2O
3 and Ag nanoparticles were added to deionized water to study their effect of evaporation rates. The results show that these nanofluid droplets evaporate at different rates (as ...indicated by the evaporation rate constant
K in the well known
D
2-law) from the base fluid. Different particles lead to different values of
K. As the particle concentration increases due to evaporation,
K values of various Ag and Fe
2O
3 nanofluids go through a transition from one value to another, further demonstrating the effect of increasing nanoparticle concentration. The implication for the heat of vaporization (
h
fg
) is discussed.
Muon tracking detector for the air shower experiment KASCADE Doll, P; Bartl, W; Büttner, C ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2002, Letnik:
488, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A large area streamer tube detector, located within the KASCADE experiment, has been built with the aim to identify muons and their directions from extensive air showers by track measurements under ...more than 18 r.l. shielding. 1000 streamer tube chambers of
4
m
length have been produced and tested. The detector concept is presented. The influence of the design and operational factors on the detector performance are shown. Various approaches to determine the angular resolution of the muon tracking detector are discussed.
Campomanesia adamantium (Cambess.) O. Berg. is originally from Brazil. Its leaves and fruits have medicinal properties such as anti-inflammatory, antidiarrheal and antiseptic properties. However, the ...mutagenic potential of this species has been reported in few studies. This study describes the mutagenic/antimutagenic, splenic phagocytic, and apoptotic activities of C. adamantium hydroethanolic extract with or without cyclophosphamide in Swiss mice. The animals orally received the hydroethanolic extract at doses of 30, 100, or 300 mg/kg with or without 100 mg/kg cyclophosphamide. Mutagenesis was evaluated by performing the micronucleus assay after treatment for 24, 48, and 72 h, while splenic phagocytic and apoptotic effects were investigated after 72 h. Short-term exposure of 30 and 100 mg/kg extract induced mild clastogenic/aneugenic effects and increased splenic phagocytosis and apoptosis in the liver, spleen, and kidneys. When the extract was administered in combination with cyclophosphamide, micronucleus frequency and apoptosis reduced. Extract components might affect cyclophosphamide metabolism, which possibly leads to increased clearance of this chemotherapeutic agent. C. adamantium showed mutagenic activity and it may decrease the effectiveness of drugs with metabolic pathways similar to those associated with cyclophosphamide. Thus, caution should be exercised while consuming these extracts, especially when received in combination with other drugs.
You The Air Microwave Yield (AMY) experiment investigate the molecular bremsstrahlung radiation emitted in the GHz frequency range from an electron beam induced air-shower. The measurements have been ...performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories with a 510 MeV electron beam in a wide frequency range between 1 and 20 GHz. We present the apparatus and the results of the tests performed.
ABSTRACT The events recorded by ARGO-YBJ in more than five years of data collection have been analyzed to determine the diffuse gamma-ray emission in the Galactic plane at Galactic longitudes 25° < l ...< 100° and Galactic latitudes . The energy range covered by this analysis, from ∼350 GeV to ∼2 TeV, allows the connection of the region explored by Fermi with the multi-TeV measurements carried out by Milagro. Our analysis has been focused on two selected regions of the Galactic plane, i.e., 40° < l < 100° and 65° < l < 85° (the Cygnus region), where Milagro observed an excess with respect to the predictions of current models. Great care has been taken in order to mask the most intense gamma-ray sources, including the TeV counterpart of the Cygnus cocoon recently identified by ARGO-YBJ, and to remove residual contributions. The ARGO-YBJ results do not show any excess at sub-TeV energies corresponding to the excess found by Milagro, and are consistent with the predictions of the Fermi model for the diffuse Galactic emission. From the measured energy distribution we derive spectral indices and the differential flux at 1 TeV of the diffuse gamma-ray emission in the sky regions investigated.
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