E. Kemp

Measurement of the velocity of neutrinos from the CNGS beam with the large volume detector.

We report the measurement of the time of flight of ∼17 GeV ν(μ) on the CNGS baseline (732 km) with the Large Volume Detector (LVD) at the Gran Sasso Laboratory. The CERN-SPS accelerator has been operated from May 10th to May 24th 2012, with a tightly bunched-beam structure to allow the velocity of neutrinos to be accurately measured on an event-by-event basis. LVD has detected 48 neutrino events, associated with the beam, with a high absolute time accuracy. These events allow us to establish the following limit on the difference between the neutrino speed and the light velocity: -3.8 × 10(-6) < (v(ν)-c)/c < 3.1 × 10(-6) (at 99% C.L.). This value is an order of magnitude lower than previous direct measurements.

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

Upper limit on the prompt muon flux derived from the LVD underground experiment

\theta_{13}

Performances and stability of a 2.4 ton Gd organic liquid scintillator target for bar nue detection

, presently unknown. Finally we discuss the astrophysical uncertainties, showing their importance and comparing it with the effect of neutrino oscillations on the expected signal.

Effects of neutrino oscillations on the supernova signal in LVD

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured depth-angular distribution of muon intensities has been used to obtain the normalization factor, A, the power index, gamma, of the primary all-nucleon spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the main parameters which determine the spectrum of cosmic ray muons at the sea level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c<2.0 x 10^-3 (95% C.L.) have been obtained. The upper limit to the prompt muon flux favours the models of charm production based on QGSM and the dual parton model.

Study of single muons with the Large Volume Detector at the Gran Sasso Laboratory

In this work we report the performances and the chemical and physical properties of a 2 1:2 ton organic liquid scintillator target doped with Gd up to 0:1%, and the results of a 2 year long stability survey. In particular we have monitored the amount of both Gd and primary uor actually in solution, the optical and uorescent properties of the Gd-doped liquid scintillator (GdLS) and its performances as a neutron detector, namely neutron capture eciency and average capture time. The experimental survey is ongoing, the target being continuously monitored. After two years from the doping time the performances of the Gd-doped liquid scintillator do not show any hint of degradation and instability; this conclusion comes both from the laboratory measurements and from the in-tank measurements. This is the largest stable Gd-doped organic liquid scintillator target ever produced and continuously operated for a long period.

Using spherical wavelets to search for magnetically-induced alignment in the arrival directions of ultra-high energy cosmic rays

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.Abstract 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 ν properties, such as normal or inverted ν mass hierarchy, and/or adiabatic or non adiabatic MSW resonances associated to U e3 . Of particular importance are the charged current (c.c.) reactions on 12 C: oscillations increase by almost one order of magnitude the number of events expected from this channel.

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

The present study is based on the sample of 2.9×106 single muons observed by the Large Volume Detector (LVD) at the underground Gran Sasso Laboratory during 36 500 live hours from June 1992 to February 1998. We have measured the muon intensity at slant depths from 3 to 20 km w.e. Most events are high-energy downward muons produced by meson decay in the atmosphere. The analysis of these muons has revealed the power index γ of the π and K spectrum: γ=2.76±0.05. The remainders are horizontal muons produced by the neutrino interactions in the rock surrounding the LVD. The value of this flux near 90° is (6.1±2.7)×10−13 cm−2 s−1 sr−1. The results are compared with the Monte Carlo simulations and the world data.

The Angra Project: Monitoring Nuclear Reactors with Antineutrino Detectors

Abstract Due to the action of the intervening cosmic magnetic fields, ultra-high energy cosmic rays (UHECRs) can be deflected in such a way as to create clustered energy-ordered filamentary structures in the arrival direction of these particles, the so-called multiplets. In this work we propose a new method based on the spherical wavelet transform to identify multiplets in sky maps containing arrival directions of UHECRs. The method is illustrated in simulations with a multiplet embedded in isotropic backgrounds with different numbers of events. The efficiency of the algorithm is assessed through the calculation of Type I and II errors.

A cosmic rays based method to detect and correct PMT gain variations for the ν-Angra veto system

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.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.