Estimations of the Distances of Stellar Collapses in the Galaxy by Analyzing the Energy Spectrum of Neutrino Bursts

The neutrino telescopes of the present generation, depending on their specific features, can reconstruct the neutrino spectra from a galactic burst. Since the optical counterpart could be not available, it is desirable to have at hand alternative methods to estimate the distance of the supernova explosion using only the neutrino data. In this work we present preliminary results on the method we are proposing to estimate the distance from a galactic supernova based only on the spectral shape of the neutrino burst and assumptions on the gravitational binding energy released an a typical supernova explosion due to stellar collapses.Comment: Proceedings of the Second International Symposium on Strong Electromagnetic Fields and Neutron Stars (SMFNS 2011) Instituto de Cibern\'etica, Matem\'atica y F\'isica (ICIMAF) Sociedad Cubana de F\'isica (SCF) Varadero, Cuba, 5-7 May 201

The primary cosmic ray composition between 10**15 and 10**16 eV from Extensive Air Showers electromagnetic and TeV muon data

The cosmic ray primary composition in the energy range between 10**15 and 10**16 eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 10**5 m**2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m**2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (Ne) measured by EAS-TOP and the muon number (Nmu) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30 degrees. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual Nmu-Ne studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He). The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.Comment: Submitted to Astroparticle Physic

SNEWS: The SuperNova Early Warning System

This paper provides a technical description of the SuperNova Early Warning System (SNEWS), an international network of experiments with the goal of providing an early warning of a galactic supernova.Comment: 25 pages, for New Journal of Physics Focus Issue on Neutrino Physic

SN neutrinos in LVD

The Large Volume Detector (LVD) in the INFN Gran Sasso National Laboratory (LNGS), Italy, is a nu observatory mainly designed to study low energy neutrinos from the gravitational collapse of galactic objects. The experiment has been monitoring the Galaxy since June 1992, under increasing larger configurations: in January 2001 it has reached its final active mass M = 1 kt. Next year it will celebrate twenty years of operation. No burst candidate has been found over 6314 days of live-time, since June 6$^{th}$ 1992 to March 27$^{th}$ 2011, resulting 90 per cent c.l. upper limit to the rate of gravitational stellar collapses in the Galaxy (D $\leq$ 20 kpc) is 0.13 y$^{-1}$. Since July 2005 LVD participates to the Supernovae Early Warning System (SNEWS), the network of SN neutrino observatories whose main goal is to provide the astronomical community with a prompt alert for the next galactic core collapse supernova explosion. Since 2006 acts as a far beam monitor for the Cern Neutrinos to Gran Sasso (CNGS) project, the high energy, wide band nu/mu beam, set up at Cern and sent towards the LNGS. Possible upgrade of the experiment have been studied and discussed in the last years

Possible explanation of the neutrino signal from SN1987A detected with the LSD

On February 23 1987 in 2:52 UT the neutrino telescope LSD under Mont Blanc detected neutrino signal, which could not be explained within the framework of the standard collapse model. We show that the LSD signal could be a consequence of the detection of gamma-quanta emitted from neutron-capture reactions on by iron nuclei contained in the composition of the experimental setup. Neutrons are produced in neutrino-nuclei reactions in the surrounding granite rock and steel structures of the detector

Possible explanation of the neutrino signal from SN1987A detected with the LSD

On February 23 1987 in 2:52 UT the neutrino telescope LSD under Mont Blanc detected neutrino signal, which could not be explained within the framework of the standard collapse model. We show that the LSD signal could be a consequence of the detection of gamma-quanta emitted from neutron-capture reactions on by iron nuclei contained in the composition of the experimental setup. Neutrons are produced in neutrino-nuclei reactions in the surrounding granite rock and steel structures of the detector

Underground flux of atmospheric muons and its variations with 25 years of data of the LVD experiment

International audienceThe Large Volume Detector (LVD) is a 1 kton liquid scintillator detector located at Laboratori Nazionali del Gran Sasso, Italy, at the average depth of 3600 m w.e.The experiment has been continuously taking data since June 1992.The muon dataset collected by LVD over 25 years (from 1992 to 2016) consists of $~5.5 \cdot 10^{7}$ events, being the largest ever provided by a single detector underground. The analysis of the global time series shows a modulation of muon flux underground with period of $T=(365.1\pm0.2)\,$days, an amplitude of 1.5 % and a maximum at the beginning of July. A clear correlation with atmospheric temperature variations is present, with a measured coefficient of ${\alpha_{T}= 0.93 \pm 0.02}$. This is in agreement with the expected value at LVD depth and with the value measured by other experiments in the same underground site

Doping the 1 kton Large Volume Detector with Gd

International audienceThe Large Volume Detector (LVD) in the INFN Gran Sasso National Laboratory (LNGS), Italy, is a ν observatory which has been monitoring the Galaxy since June 1992 to study neutrinos from core collapse supernovae. The experiment in the present configuration is made by 840 scintillator detectors, for a total active mass of 1000 tons. The detector sensitivity to neutrino bursts due to a core collapse supernova has been already discussed in term of maximum detectable distance. In this paper we evaluate the improvements that LVD could obtain if all its active scintillator mass was doped with a small amount (0.14% in weight) of Gadolinium. We simulated neutron captures following bar nue inverse beta decay reactions in one LVD counter (1.2 ton) with Gd doped liquid scintillator obtaining an efficiency for the detection of this process of ηn|Gd = 80% and a mean capture time τ = 25μs, in good agreement with the results obtained by the measures. This implies a gain of a factor ∼ 20 in the signal to noise ratio for neutron capture detection with respect to the undoped liquid scintillator. We discuss how the captures of neutrons from rock radioactivity on Gd modify the background conditions of the detector and we calculate the curves expressing the sensitivity to a bar nue burst from core collapse supernovae depending on the distance of the collapsing star. It results that doping the 1 kton Large Volume Detector with Gd would assure a 90% detection efficiency at the distance of the Large Magellanic Cloud (50 kpc), an achievement which is equivalent to that obtained by doubling the number of counters in LVD

The hypothesis that Helicobacter pylori predisposes to Alzheimer's disease is biologically plausible

There is epidemiological evidence that H. pylori might predispose to Alzheimer's disease. To understand the cellular processes potentially linking such unrelated events, we incubated the human gastric cells MNK-28 with the H. pylori peptide Hp(2-20). We then monitored the activated genes by global gene expression. The peptide modulated 77 genes, of which 65 are listed in the AlzBase database and include the hallmarks of Alzheimer's disease: APP, APOE, PSEN1, and PSEN2. A large fraction of modulated genes (30 out of 77) belong to the inflammation pathway. Remarkably, the pathways dis-regulated in Alzheimer's and Leasch-Nyhan diseases result dis-regulated also in this study. The unsuspected links between such different diseases - though still awaiting formal validation - suggest new directions for the study of neurological diseases