467 research outputs found
Limits on Electron Neutrino Disappearance from the KARMEN and LSND electron neutrino - Carbon Cross Section Data
This paper presents a combined analysis of the KARMEN and LSND nu_e-carbon
cross section measurements within the context of a search for nu_e
disappearance at high Delta m^2. KARMEN and LSND were located at 17.7 m and
29.8 m respectively from the neutrino source, so the consistency of the two
measurements, as a function of antineutrino energy, sets strong limits on
neutrino oscillations. Most of the allowed region from the nu_e disappearance
analysis of the Gallium calibration data is excluded at >95% CL and the best
fit point is excluded at 3.6. Assuming CPT conservation, comparisons
are also made to the oscillation analyses of reactor antineutrino data.Comment: Published versio
Confronting the short-baseline oscillation anomalies with a single sterile neutrino and non-standard matter effects
We examine the MiniBooNE neutrino, MiniBooNE antineutrino and LSND
antineutrino data sets in a two-neutrino
oscillation approximation subject to non-standard matter effects. We assume
those effects can be parametrized by an -independent effective potential,
, experienced only by an intermediate, non-weakly-interacting
(sterile) neutrino state which we assume participates in the oscillation, where
corresponds to neutrino/antineutrino propagation. We discuss the
mathematical framework in which such oscillations arise in detail, and derive
the relevant oscillation probability as a function of the vacuum oscillation
parameters and , and the matter effect
parameter . We are able to successfully fit all three data sets, including
the MiniBooNE low energy excess, with the following best-fit model parameters:
eV, , and
eV. The -probability for the best fit
corresponds to 21.6%, to be compared to 6.8% for a fit where has been set
to zero, corresponding to a (3+1) sterile neutrino oscillation model. We find
that the compatibility between the three data sets corresponds to 17.4%, to be
compared to 2.3% for . Finally, given the fit results, we examine
consequences for reactor, solar, and atmospheric oscillations. For this paper,
the presented model is empirically driven, but the results obtained can be
directly used to investigate various phenomenological interpretations such as
non-standard matter effects.Comment: 19 pages, 11 figures, 1 tabl
Precision Measurement of sin^2 theta_W at a Reactor
This paper presents a strategy for measuring sin^2 theta_W to ~1% at a
reactor-based experiment, using antineutrinos electron elastic scattering. This
error is comparable to the NuTeV, SLAC E158, and APV results on sin^2 theta_W,
but with substantially different contributions to the systematics. An improved
method for identifying antineutrino proton events, which serve both as a
background and as a normalization sample, is described. The measurement can be
performed using the near detector of the presently proposed reactor-based
oscillation experiments. We conclude that an absolute error of delta(sin^2
theta_W)=0.0019 may be achieved.Comment: To be Submitted to Phys. Rev.
Sterile Neutrino Fits to Short Baseline Neutrino Oscillation Measurements
This paper reviews short baseline oscillation experiments as interpreted
within the context of one, two, and three sterile neutrino models associated
with additional neutrino mass states in the ~1 eV range. Appearance and
disappearance signals and limits are considered. We show that fitting short
baseline data sets to a (3+3) model, defined by three active and three sterile
neutrinos, results in an overall goodness of fit of 67%, and a compatibility of
90% among all data sets -- to be compared to the compatibility of 0.043% and
13% for a (3+1) and a (3+2) model, respectively. While the (3+3) fit yields the
highest quality overall, it still finds inconsistencies with the MiniBooNE
appearance data sets; in particular, the global fit fails to account for the
observed MiniBooNE low-energy excess. Given the overall improvement, we
recommend using the results of (3+2) and (3+3) fits, rather than (3+1) fits,
for future neutrino oscillation phenomenology. These results motivate the
pursuit of further short baseline experiments, such as those reviewed in this
paper.Comment: Submitted to Advances in High Energy Physics Special Issue on
Neutrino Physic
Short-baseline Neutrino Oscillation Waves in Ultra-large Liquid Scintillator Detectors
Powerful new multi-kiloton liquid scintillator neutrino detectors, including
NOvA and LENA, will come on-line within the next decade. When these are coupled
with a modest-power decay-at-rest (DAR) neutrino source at short-baseline,
these detectors can decisively address the recent ambiguous signals for
neutrino oscillations at high Delta m^2. These detectors are > 50 m long, and
so with a DAR beam, the characteristic oscillation wave will be apparent over
the length of the detector, providing a powerful verification of the
oscillation phenomena. LENA can simultaneously perform numubar to nuebar
appearance and nue to nue disappearance searches with unprecedented
sensitivity. NOvA is likely limited to nue disappearance given its present
design, but also has excellent sensitivity in the high Delta m^2 region. For
the appearance channel, LENA could provide a stringent test of the LSND and
MiniBooNE signal regions at > 5 sigma with a reduced fiducial volume of 5 kt
and a 10 kW neutrino source. In addition, the LENA and NOvA disappearance
sensitivities in nue mode are complementary to the recent reactor anomaly
indicating possible nuebar disappearance and would cover this possible
oscillation signal at the 3 sigma level.Comment: 24 pages, 8 figures, 9 table
Cyclotrons as Drivers for Precision Neutrino Measurements
As we enter the age of precision measurement in neutrino physics, improved
flux sources are required. These must have a well-defined flavor content with
energies in ranges where backgrounds are low and cross section knowledge is
high. Very few sources of neutrinos can meet these requirements. However,
pion/muon and isotope decay-at-rest sources qualify. The ideal drivers for
decay-at-rest sources are cyclotron accelerators, which are compact and
relatively inexpensive. This paper describes a scheme to produce decay-at-rest
sources driven by such cyclotrons, developed within the DAEdALUS program.
Examples of the value of the high precision beams for pursuing Beyond Standard
Model interactions are reviewed. New results on a combined DAEdALUS--Hyper-K
search for CP-violation that achieve errors on the mixing matrix parameter of 4
degrees to 12 degrees are presented.Comment: This paper was invited by the journal Advances in High Energy Physics
for their upcoming special issue on "Neutrino Masses and Oscillations," which
will be published on the 100th anniversary of Pontecorvo's birt
Measuring Active-to-Sterile Neutrino Oscillations with Neutral Current Coherent Neutrino-Nucleus Scattering
Light sterile neutrinos have been introduced as an explanation for a number
of oscillation signals at eV. Neutrino oscillations at
relatively short baselines provide a probe of these possible new states. This
paper describes an accelerator-based experiment using neutral current coherent
neutrino-nucleus scattering to strictly search for active-to-sterile neutrino
oscillations. This experiment could, thus, definitively establish the existence
of sterile neutrinos and provide constraints on their mixing parameters. A
cyclotron-based proton beam can be directed to multiple targets, producing a
low energy pion and muon decay-at-rest neutrino source with variable distance
to a single detector. Two types of detectors are considered: a germanium-based
detector inspired by the CDMS design and a liquid argon detector inspired by
the proposed CLEAR experiment.Comment: 10 pages, 7 figure
Improved Parameterization of Production in p-Be Collisions at Low Energy Using Feynman Scaling
This paper describes an improved parameterization for proton-beryllium
production of secondary mesons for experiments with primary proton
beams from 8.89 to 24 GeV. The parameterization is based on Feynman scaling in
which the invariant cross section is described as a function of and
. This method is theoretically motivated and provides a better
description of the energy dependence of kaon production at low beam energies
than other parameterizations such as the commonly used "Modified Sanford-Wang"
model. This Feynman scaling parameterization has been used for the simulation
of the neutrino flux from the Booster Neutrino Beam (BNB) at Fermilab and has
been shown to agree with the neutrino interaction data from the SciBooNE
experiment. This parameterization will also be useful for future neutrino
experiments with low primary beam energies, such as those planned for the
Project X accelerator.Comment: 15 pages, 13 figure
New Clues About Light Sterile Neutrinos: Preference for Models with Damping Effects in Global Fits
This article reports global fits of short-baseline neutrino data to
oscillation models involving light sterile neutrinos. In the commonly-used 3+1
plane wave model, there is a well-known 4.9 tension between data sets
sensitive to appearance and disappearance of neutrinos. We find that models
that damp the oscillation prediction for the reactor data sets, especially at
low energy, substantially improve the fits and reduce the tension. We consider
two such scenarios. The first introduces one sterile neutrino (3+1) and the
Quantum Mechanical wavepacket effect that accounts for the source size in
reactor experiments. We find that inclusion of the wavepacket effect greatly
improves the overall fit compared to the null model by ( improvement) with best-fit and wavepacket length of 67 fm; internal tension is
reduced to 3.6. If reactor-data only is fit, that the wavepacket
preferred length is 91 fm ( fm at 99\% CL). The second model introduces
oscillations involving sterile flavor and allows the decay of the heavier,
mostly sterile, mass state . This model introduces a damping term
similar to the wavepacket effect, but across all experiments. Compared to null,
this has a ( improvement) with
preferred and decay ;
and internal tension of 3.7.Comment: Errors are the prospect plot updated from the collaboration. Tension
figures have updated plot styl
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