Improved determination of sterile neutrino dark matter spectrum

The putative recent indication of an unidentified 3.55 keV X-ray line in certain astrophysical sources is taken as a motivation for an improved theoretical computation of the cosmological abundance of 7.1 keV sterile neutrinos. If the line is interpreted as resulting from the decay of Warm Dark Matter, the mass and mixing angle of the sterile neutrino are known. Our computation then permits for a determination of the lepton asymmetry that is needed for producing the correct abundance via the Shi-Fuller mechanism, as well as for an estimate of the non-equilibrium spectrum of the sterile neutrinos. The latter plays a role in structure formation simulations. Results are presented for different flavour structures of the neutrino Yukawa couplings and for different types of pre-existing lepton asymmetries, accounting properly for the charge neutrality of the plasma and incorporating approximately hadronic contributions.

Dark matter sensitivity of multi-ton liquid xenon detectors

We study the sensitivity of multi ton-scale time projection chambers using a liquid xenon target, e.g., the proposed DARWIN instrument, to spin-independent and spin-dependent WIMP-nucleon scattering interactions. Taking into account realistic backgrounds from the detector itself as well as from neutrinos, we examine the impact of exposure, energy threshold, background rejection efficiency and energy resolution on the dark matter sensitivity. With an exposure of 200 t x y and assuming detector parameters which have been already demonstrated experimentally, spin-independent cross sections as low as 2.5×10−49 cm2 can be probed for WIMP masses around 40 GeV/c2. Additional improvements in terms of background rejection and exposure will further increase the sensitivity, while the ultimate WIMP science reach will be limited by neutrinos scattering coherently off the xenon nuclei.

Discovery of τ Neutrino Appearance in the CNGS Neutrino Beam with the OPERA Experiment

The OPERA experiment was designed to search for νµ → ντ oscillations in appearance mode, i.e. by detecting the τ leptons produced in charged current ντ interactions. The experiment took data from 2008 to 2012 in the CERN Neutrinos to Gran Sasso beam. The observation of the νµ → ντ appearance, achieved with four candidate events in a subsample of the data, was previously reported. In this Letter, a fifth ντ candidate event, found in an enlarged data sample, is described. Together with a further reduction of the expected background, the candidate events detected so far allow us to assess the discovery of νµ → ντ oscillations in appearance mode with a significance larger than 5 σ.

Measurement of the electron neutrino charged-current interaction rate on water with the T2K ND280 π0 detector

This paper presents a measurement of the charged current interaction rate of the electron neutrino beam component of the beam above 1.5 GeV using the large fiducial mass of the T2K π0 detector. The predominant portion of the νe flux (∼85%) at these energies comes from kaon decays. The measured ratio of the observed beam interaction rate to the predicted rate in the detector with water targets filled is 0.89 ± 0.08 (stat.) ± 0.11 (sys.), and with the water targets emptied is 0.90 ± 0.09 (stat.) ± 0.13 (sys.). The ratio obtained for the interactions on water only from an event subtraction method is 0.87 ± 0.33 (stat.) ± 0.21 (sys.). This is the first measurement of the interaction rate of electron neutrinos on water, which is particularly of interest to experiments with water Cherenkov detectors.

The discovery of the appearance of vμ − vτ oscillations

Almost 20 years after the first conceptual design of the experiment, five years of running in the Gran Sasso underground laboratory (LNGS), and billions of billions muon-neutrinos sent from CERN along the CNGS beam, in 2015 the OPERA neutrino detector has allowed the long-awaited discovery of the direct transformation (oscillation) of muon-neutrinos into tau-neutrinos. This result unambiguously confirms the interpretation of the so-called atmospheric channel, after the discovery of neutrino oscillations by the Super-Kamiokande Collaboration in 1998.

Patenting Systems, Patentable Subject Matter, and Prior Art

The International School of Solid State Physics presented the 56th Course"Materials for Renewable Energy” in Erice (Italy), from July 18th to 28th 2012. This course was sponsored by the Italian Ministry of Education, University and Scientific Research, the Materials Research Society and the European Materials Research Society. The event was hosted at the "Ettore Majorana Foundation and Centre for Scientific Culture”. The school reviewed critical materials issues for the production and storage of renewable and sustainable energy. The aim of the School was to present the state-of-the-art and future perspectives in this critical area. It was to bring together the international community of students, young scientists, and experts in a unique atmosphere for reciprocal benefits in terms of enthusiasm, knowledge and new ideas.

Reconstruction of SN1987a event

IMB (Irvine, Michigan, Brookline), a collaboration between the University of Michigan, the University of California at Irvine, and the U.S. Department of Energy, was an experiment designed to determine the ultimate stability of matter. Using data from the PMT hits (bl003799) the neutrino interaction point and direction in the detector are shown (long purple line). The produced position (short purple line) is also shown along with its cherenkov cone hitting the walls of the detector (yellow squares).

Supernove 1987a before and after explosion

IMB (Irvine, Michigan, Brookline), a collaboration between the University of Michigan, the University of California at Irvine, and the U.S. Department of Energy, was an experiment designed to determine the ultimate stability of matter. The blue giant star Sanduleak in the large magellenic cloud exploded 170,000 years ago giving off a pulse of neutrinos that arrived at earth on 23 February 1987. For a few weeks it was as bright as 100 million suns.

Supernova 1987a neutrino event in IMB detector

IMB (Irvine, Michigan, Brookline), a collaboration between the University of Michigan, the University of California at Irvine, and the U.S. Department of Energy, was an experiment designed to determine the ultimate stability of matter. One of eight events recorded by IMB during the few seconds that the neutrino pulse from SN1987a passed through the detector. View looking into the south wall.

Sphere plot of SN1987a event

IMB (Irvine, Michigan, Brookline), a collaboration between the University of Michigan, the University of California at Irvine, and the U.S. Department of Energy, was an experiment designed to determine the ultimate stability of matter. PMT [photomultiplier tubes] hits from SN [supernovae] event projected onto sphere.

Gamma-ray and neutrino fluxes from Heavy Dark Matter in the Galactic Center

We present a study of the Galactic Center region as a possible source of both secondary gamma-ray and neutrino fluxes from annihilating dark matter. We have studied the gamma-ray flux observed by the High Energy Stereoscopic System (HESS) from the J1745-290 Galactic Center source. The data are well fitted as annihilating dark matter in combination with an astrophysical background. The analysis was performed by means of simulated gamma spectra produced by Monte Carlo event generators packages. We analyze the differences in the spectra obtained by the various Monte Carlo codes developed so far in particle physics. We show that, within some uncertainty, the HESS data can be fitted as a signal from a heavy dark matter density distribution peaked at the Galactic Center, with a power-law for the background with a spectral index which is compatible with the Fermi-Large Area Telescope (LAT) data from the same region. If this kind of dark matter distribution generates the gamma-ray flux observed by HESS, we also expect to observe a neutrino flux. We show prospective results for the observation of secondary neutrinos with the Astronomy with a Neutrino Telescope and Abyss environmental RESearch project (ANTARES), Ice Cube Neutrino Observatory (Ice Cube) and the Cubic Kilometer Neutrino Telescope (KM3NeT). Prospects solely depend on the device resolution angle when its effective area and the minimum energy threshold are fixed.

Réduction du bruit de fond en vue de la détection de la matière sombre avec le projet PICASSO

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Réduction du bruit de fond en vue de la détection de la matière sombre avec le projet PICASSO

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

The role of nuclear physics in supernovae and the evolution of neutron stars, Neutrino Opacities, Equation of State, Transport Coefficients, and Dark Matter Production

Thesis (Ph.D.)--University of Washington, 2016-08

The Askaryan radio array

The Askar'yan Radio Array (ARA), a neutrino detector to be situated at the South Pole next to the IceCube detector, will be sensitive to ultrahigh-energy cosmic neutrinos above 0.1 EeV and will have the greatest sensitivity within the favored energy range from 0.1 EeV up to 10 EeV. Neutrinos of this energy are guaranteed by current observations of the GZK-cutoff by the HiRes and Pierre Auger Observatories. The detection method is based on Cherenkov emission by a neutrino induced cascade in the ice, coherent at radio wavelengths, which was predicted by Askar'yan in 1962 and verified in beam tests at SLAC in 2006. The detector is planned to consist of 37 stations with 16 antennas each, deployed at depths of up to 200 m under the ice surface. During the last two polar seasons (2010-2011, 2011-2012), a prototype station and a first detector station were successfully deployed and are taking data. These data have been and are currently being analyzed to study the ambient noise background and the radio frequency properties of the South Pole ice sheet. A worldwide collaboration is working on the planning, construction and data analysis of the detector array. This article will give a short report on the status of the ARA detector and show recent results from the recorded data. © 2013 AIP Publishing LLC.