384 research outputs found
The Physics Role and Potential of future Atmospheric Detectors
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
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
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
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 , created via the decay of a significantly more
massive and long-lived non-thermal relic , which forms the bulk of DM. If
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 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
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'' ( 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 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 for large , providing a
useful discriminator between different geophysical models.Comment: 27 pages, 11 figures. Minor changes, references added; version to
appear in Phys. Rev.
PUBLIC AND PRIVATE FOOD ASSISTANCE CHOICES OF FOOD NEEDY FAMILIES
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,
- …