354 research outputs found

    The Physics Role and Potential of future Atmospheric Detectors

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    We discuss the physics capabilities of basic types of future atmospheric detectors being considered at present, with their strengths and limitations, and compare them with those of long baseline (LBL) experiments. We also argue that recent studies signal the importance of synergistically combining complementary features of both these classes of experiments in order to accrue maximum benefit towards furthering our goal of building a complete picture of neutrino properties and parameters.Comment: Based on a Plenary Talk at NUFACT 09, Chicago; 10 pages, 6 figure

    Atmospheric neutrinos as a probe of eV^2-scale active-sterile oscillations

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    The down-going atmospheric \nu_{\mu} and {\bar{\nu_{\mu}}} fluxes can be significantly altered due to the presence of eV^2-scale active-sterile oscillations. We study the sensitivity of a large Liquid Argon detector and a large magnetized iron detector (like the proposed ICAL at INO) to these oscillations. Such oscillations are indicated by results from LSND, and more recently, from MiniBooNE and from reanalyses of reactor experiments following recent recalculations of reactor fluxes. There are other tentative indications of the presence of sterile states in both the \nu and {\bar{\nu}} sectors as well. Using the allowed sterile parameter ranges in a 3+1 mixing framework in order to test these results, we perform a fit assuming active-sterile oscillations in both the muon neutrino and antineutrino sectors, and compute oscillation exclusion limits using atmospheric down-going muon neutrino and anti-neutrino events. We find that (for both \nu_{\mu} and {\bar{\nu_{\mu}}}) a Liquid Argon detector, an ICAL-like detector or a combined analysis of both detectors with an exposure of 1 Mt yr provides significant sensitivity to regions of parameter space in the range 0.1 < \Delta m^2 < 5 eV^2 for \sin^2 2\Theta_{\mu\mu}\geq 0.08. Thus atmospheric neutrino experiments can provide complementary coverage in these regions, improving sensitivity limits in combination with bounds from other experiments on these parameters. We also analyse the bounds using muon antineutrino events only and compare them with the results from MiniBooNE.Comment: 9 pages, 7 figures. Major revisions, analysis of Liquid Argon detector added. Version to appear in Physical Review D (Brief Reports

    Pair production of helicity-flipped neutrinos in supernovae

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    The emissivity was calculated for the pair production of helicity-flipped neutrinos, in a way that can be used in supernova calculations. Also presented are simple estimates which show that such process can act as an efficient energy-loss mechanism in the shocked supernova core, and this fact is used to extract neutrino mass limits from SN 1987A neutrino observations

    The Direct Detection of Boosted Dark Matter at High Energies and PeV events at IceCube

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    We study the possibility of detecting dark matter directly via a small but energetic component that is allowed within present-day constraints. Drawing closely upon the fact that neutral current neutrino nucleon interactions are indistinguishable from DM-nucleon interactions at low energies, we extend this feature to high energies for a small, non-thermal but highly energetic population of DM particle χ\chi, created via the decay of a significantly more massive and long-lived non-thermal relic ϕ\phi, which forms the bulk of DM. If χ\chi interacts with nucleons, its cross-section, like the neutrino-nucleus coherent cross-section, can rise sharply with energy leading to deep inelastic scattering, similar to neutral current neutrino-nucleon interactions at high energies. Thus, its direct detection may be possible via cascades in very large neutrino detectors. As a specific example, we apply this notion to the recently reported three ultra-high energy PeV cascade events clustered around 121-2 PeV at IceCube (IC). We discuss the features which may help discriminate this scenario from one in which only astrophysical neutrinos constitute the event sample in detectors like IC.Comment: v1: 6 pages, 4 figures; v2: More references added, minor text changes for clarification; v3: Title change, major revision, updated references; v4: Corrected Fig. 1b, Version published in JCA

    Physics with a very long neutrino factory baseline

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    We discuss the neutrino oscillation physics of a very long neutrino factory baseline over a broad range of lengths (between 6000 km and 9000 km), centered on the ``magic baseline'' (\sim 7500 km) where correlations with the leptonic CP phase are suppressed by matter effects. Since the magic baseline depends only on the density, we study the impact of matter density profile effects and density uncertainties over this range, and the impact of detector locations off the optimal baseline. We find that the optimal constant density describing the physics over this entire baseline range is about 5% higher than the average matter density. This implies that the magic baseline is significantly shorter than previously inferred. However, while a single detector optimization requires fine-tuning of the (very long) baseline length, its combination with a near detector at a shorter baseline is much less sensitive to the far detector location and to uncertainties in the matter density. In addition, we point out different applications of this baseline which go beyond its excellent correlation and degeneracy resolution potential. We demonstrate that such a long baseline assists in the improvement of the θ13\theta_{13} precision and in the resolution of the octant degeneracy. Moreover, we show that the neutrino data from such a baseline could be used to extract the matter density along the profile up to 0.24% at 1σ1 \sigma for large sin22θ13\sin^2 2 \theta_{13}, providing a useful discriminator between different geophysical models.Comment: 27 pages, 11 figures. Minor changes, references added; version to appear in Phys. Rev.


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    A bivariate probit model was used to determine public and private food assistance participation among the population below 125 percent poverty level, using the Current Population Survey data. Food stamp use and food pantry use were complements. Household income, food insecurity status, household structure, and rural residence affected participation decisions.Food Security and Poverty,