arXiv subjects

P. Galeotti

Publications and source records attributed to P. Galeotti.

33 records · Page 2Linked to original sources

arXiv2011

Mean Interplanetary Magnetic Field Measurement Using the ARGO-YBJ Experiment

The sun blocks cosmic ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic ray particles are positive charged, the magnetic field between the sun and the earth deflects them from straight trajectories and results in a shift of the shadow from the true location of the sun. Here we show that the shift measures the intensity of the field which is transported by the solar wind from the sun to the earth.

astro-ph.SR↗

arXiv2010

The proton-air inelastic cross-section measurement at $\sqrt{s} \approx $ 2 TeV from EAS-TOP experiment

The proton-air inelastic cross section value \sigmapairin=338$\pm$21({\it stat})$\pm$19({\it syst})-28({\it syst}) mb at $\sqrt{s} \approx $ 2 TeV has been measured by the EAS-TOP Extensive Air Shower experiment. The absorption length of cosmic ray proton primaries cascades reaching the maximum development at the observation level is obtained from the flux attenuation for different zenith angles (i.e. atmospheric depths). The analysis, including the effects of the heavier primaries contribution and systematic uncertainties, is described. The experimental result is compared with different high energy interaction models and the relationships with the {\it pp} ($\bar pp$) total cross section measurements are discussed.

astro-ph.HE↗

arXiv2009

Evolution of the cosmic ray anisotropy above 10^{14} eV

The amplitude and phase of the cosmic ray anisotropy are well established experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution into the energy region 10^{14}-10^{16} eV can provide a significant tool for the understanding of the steepening ("knee") of the primary spectrum. In this letter we extend the EAS-TOP measurement performed at E_0 around 10^{14} eV, to higher energies by using the full data set (8 years of data taking). Results derived at about 10^{14} and 4x10^{14} eV are compared and discussed. Hints of increasing amplitude and change of phase above 10^{14} eV are reported. The significance of the observation for the understanding of cosmic ray propagation is discussed.

astro-ph.HE↗

arXiv2008

SN1987A: Revisiting the Data and the Correlation between Neutrino and Gravitational Detectors

We re-examine the data taken by the neutrino detectors during the supernova SN1987A. It is found that the Kamiokande data, in addition to the well known burst at 7:35 hours UT, show another one at 7:54 hours, with seven pulses in 6.2 seconds. This second burst supports the idea that the duration of the collapse was much longer than a few seconds, as already suggested by the LSD detection at 2:56 hours the same day, i.e. four and a half hours earlier. The correlations between the gravitational wave detectors (Rome and Maryland) and the neutrino detectors are also revisited. It is shown that the g.w. detectors exhibit significant correlations with both the LSD and the Kamiokande detectors over periods of one-two hours that are centered, in both cases, at the LSD time.

gr-qc↗

arXiv2007

First CNGS events detected by LVD

The CERN Neutrino to Gran Sasso (CNGS) project aims to produce a high energy, wide band $ν_μ$ beam at CERN and send it toward the INFN Gran Sasso National Laboratory (LNGS), 732 km away. Its main goal is the observation of the $ν_τ$ appearance, through neutrino flavour oscillation. The beam started its operation in August 2006 for about 12 days: a total amount of $7.6~10^{17}$ protons were delivered to the target. The LVD detector, installed in hall A of the LNGS and mainly dedicated to the study of supernova neutrinos, was fully operating during the whole CNGS running time. A total number of 569 events were detected in coincidence with the beam spill time. This is in good agreement with the expected number of events from Montecarlo simulations.

hep-ex↗

arXiv2007

On-line recognition of supernova neutrino bursts in the LVD detector

In this paper we show the capabilities of the Large Volume Detector (INFN Gran Sasso National Laboratory) to identify a neutrino burst associated to a supernova explosion, in the absence of an "external trigger", e.g., an optical observation. We describe how the detector trigger and event selection have been optimized for this purpose, and we detail the algorithm used for the on-line burst recognition. The on-line sensitivity of the detector is defined and discussed in terms of supernova distance and electron anti-neutrino intensity at the source.

astro-ph↗

arXiv2007

Detection of the Cherenkov light diffused by Sea Water with the ULTRA Experiment

The study of Ultra High Energy Cosmic Rays represents one of the most challenging topic in the Cosmic Rays and in the Astroparticle Physics fields. The interaction of primary particles with atmospheric nuclei produces a huge Extensive Air Shower together with isotropic emission of UV fluorescence light and highly directional Cherenkov photons, that are reflected/diffused isotropically by the impact on the Earth's surface or on high optical depth clouds. For space-based observations, detecting the reflected Cherenkov signal in a delayed coincidence with the fluorescence light improves the accuracy of the shower reconstruction in space and in particular the measurement of the shower maximum, giving a strong signature for discriminating hadrons and neutrinos, and helping to estimate the primary chemical composition. Since the Earth's surface is mostly covered by water, the ULTRA (UV Light Transmission and Reflection in the Atmosphere)experiment has been designed to provide the diffusing properties of sea water, overcoming the lack of information in this specific field. A small EAS array, made up of 5 particle detectors, and an UV optical device, have been coupled to detect in coincidence both electromagnetic and UV components. The detector was in operation from May to December, 2005, in a small private harbor in Capo Granitola (Italy); the results of these measurements in terms of diffusion coefficient and threshold energy are presented here.

astro-ph↗

arXiv2007

Sn1987a Revisited after 20 Years: May the Supernova Bang More Than Once?

The observations of supernova 1987A in underground detectors are revisited. It is shown that, while the LSD detector in the Mont Blanc Laboratory observed only one burst at 2h 52min 36.8sec U.T., the Kamiokande data show a possible second burst, in addition to the well known one at 7h 35min 33.7sec U.T. This second burst consists of a cluster of seven pulses, well above the energy threshold of the detector, observed during 6.2 seconds starting at 7h 54min 22.2sec U.T. Do these observations imply a long duration of the collapse?

gr-qc↗

arXiv2006

Study of the effect of neutrino oscillations on the supernova neutrino signal in the LVD detector

The LVD detector, located in the INFN Gran Sasso National Laboratory (Italy), studies supernova neutrinos through the interactions with protons and carbon nuclei in the liquid scintillator and interactions with the iron nuclei of the support structure. We investigate the effect of neutrino oscillations in the signal expected in the LVD detector. The MSW effect has been studied in detail for neutrinos travelling through the collapsing star and the Earth. We show that the expected number of events and their energy spectrum are sensitive to the oscillation parameters, in particular to the mass hierarchy and the value of $θ_{13}$, presently unknown. Finally we discuss the astrophysical uncertainties, showing their importance and comparing it with the effect of neutrino oscillations on the expected signal.

hep-ph↗

arXiv2006

Results from the ULTRA experiment in the framework of the EUSO project

The detection of Cerenkov light from EAS in a delayed coincidence with fluorescence light gives a strong signature to discriminate protons and neutrinos in cosmic rays. For this purpose, the ULTRA experiment has been designed with 2 detectors: a small EAS array (ETscope) and an UV optical device including wide field (Belenos) and narrow field (UVscope) Cerenkov light detectors. The array measures the shower size and the arrival direction of the incoming EAS, while the UV devices, pointing both to zenith and nadir, are used to determine the amount of direct and diffused coincident Cerenkov light. This information, provided for different diffusing surfaces, will be used to verify the possibility of detecting from Space the Cerenkov light produced by UHECRs with the EUSO experiment, on board the ISS.

astro-ph↗

arXiv2005

GAW, Gamma Air Watch - A Large Field of View Imaging Atmospheric Cherenkov

GAW, acronym for Gamma Air Watch, is a path-finder experiment to test the feasibility of a new generation of imaging atmospheric Cherenkov telescopes that join high flux sensitivity with large field of view capability. GAW is conceived as an array of three identical imaging telescopes disposed at the vertexes of an equilateral triangle, about 80 m side. Two main features characterize GAW with respect to all the existing and presently planned ground-based Cherenkov telescopes. The first difference concerns the optics system: GAW uses a Fresnel refractive lens (2.13 m diameter) as light collector instead of classical reflective mirror. The second main difference is the detection working mode used: the detector at the focal surface operates in single photoelectron counting mode instead of the usual charge integration one. The GAW array is planned to be located at the Calar Alto Observatory site, Spain, 2150 m a.s.l. During its first phase, only 6x6 degrees of the focal plane detector will be implemented; moving it along the field of view, the sensitivity of the telescopes will be tested observing the Crab Nebula with on-axis and off-axis pointing up to 20 deg and with energy threshold of 300 GeV and energy peak of 700 GeV. As path-finder, GAW will also monitor the Very High Energy activity of some flaring Blazars as well as will follow-up GLAST detections at high energies. In a second phase, the focal plane will be enlarged to cover a field of view of 24 deg (full); pointing along different North-South directions, GAW would reach a survey of 360x60 degrees region of the sky. GAW is a collaboration effort of Research Institutes in Italy, Portugal and Spain.

astro-ph↗

arXiv2004

Search for low energy neutrinos in correlation with the 8 events observed by the EXPLORER and NAUTILUS detectors in 2001

We report on a search for low-energy neutrino (antineutrino) bursts in correlation with the 8 time coincident events observed by the gravitational waves detectors EXPLORER and NAUTILUS (GWD) during the year 2001. The search, conducted with the LVD detector (INFN Gran Sasso National Laboratory, Italy), has considered several neutrino reactions, corresponding to different neutrino species, and a wide range of time intervals around the (GWD) observed events. No evidence for statistically significant correlated signals in LVD has been found. Assuming two different origins for neutrino emission, the cooling of a neutron star from a core-collapse supernova or from coalescing neutron stars and the accretion of shocked matter, and taking into account neutrino oscillations, we derive limits to the total energy emitted in neutrinos and to the amount of accreting mass, respectively.

astro-ph↗

arXiv2003

Study of the effect of neutrino oscillation on the supernova neutrino signal with the LVD detector

We present an update of our previous study (astro-ph/0112312) on how $ν$ oscillations affect the signal from a supernova core collapse observed in the LVD detector at LNGS. In this paper we use a recent, more precise determination of the cross section (astro-ph/0302055) to calculate the expected number of inverse beta decay events, we introduce in the simulation also the $ν$-{\rm Fe} interactions, we include the Earth matter effects and, finally, we study also the inverted mass hierarchy case.

hep-ph↗

arXiv2003

CNGS beam monitor with the LVD detector

The importance of an adequate CNGS beam monitor at the Gran Sasso Laboratory has been stressed in many papers. Since the number of internal $ν_μ$ CC and NC interactions in the various detectors will not allow to collect statistics rapidly, one should also be able to detect the $ν_μ$ CC interactions in the upstream rock. In this study we have investigated the performances of the LVD detector as a monitor for the CNGS neutrino beam. Thanks to its wide area ($13 \times 11 m^2$ orthogonal to the beam direction) LVD can detect about 120 muons per day originated by $ν_μ$ CC interactions in the rock. The LVD total mass is $\sim2 kt$. This allows to get 30 more CNGS events per day as internal $(NC + CC)$ $ν_μ$ interactions, for a total of $\sim 150$ events per day. A 3% statistical error can be reached in 7 days. Taking into account the time characteristics of the CNGS beam, the cosmic muon background can be reduced to a negligible level, of the order of 1.5 events per day.

hep-ex↗

arXiv2001

Effects of neutrino oscillations on the supernova signal in LVD

We study the impact of neutrino oscillations on the supernova neutrino signal in the Large Volume Detector (LVD). The number of expected events for a galactic supernova (D=10 kpc) is calculated, assuming neutrino masses and mixing that explain solar and atmospheric neutrino results. The possibility to detect neutrinos in different channels makes LVD sensitive to different scenarios for neutrino properties, such as normal or inverted neutrino mass hierarchy, and/or adiabatic or non adiabatic MSW resonances associated to U(e3). Of particular importance are the charged current reactions on carbon: oscillations increase by almost one order of magnitude the number of events expected from this channel.

astro-ph↗