31 research outputs found
Seasonal Variation of Multiple-Muon Cosmic Ray Air Showers Observed in the NOvA Detector on the Surface
We report the rate of cosmic ray air showers with multiplicities exceeding 15
muon tracks recorded in the NOvA Far Detector between May 2016 and May 2018.
The detector is located on the surface under an overburden of 3.6 meters water
equivalent. We observe a seasonal dependence in the rate of multiple-muon
showers, which varies in magnitude with multiplicity and zenith angle. During
this period, the effective atmospheric temperature and surface pressure ranged
between 210 K to 230 K and 940mbar to 990mbar, respectively; the shower rates
are anti-correlated with the variation in the effective temperature. The
variations are about 30% larger for the highest multiplicities than the lowest
multiplicities and 20% larger for showers near the horizon than vertical
showers
Search for multimessenger signals in NOvA coincident with LIGO/Virgo detections
Using the NOvA neutrino detectors, a broad search has been performed for any signal coincident with 28 gravitational wave events detected by the LIGO/Virgo Collaboration between September 2015 and July 2019. For all of these events, NOvA is sensitive to possible arrival of neutrinos and cosmic rays of GeV and higher energies. For five (seven) events in the NOvA Far (Near) Detector, timely public alerts from the LIGO/Virgo Collaboration allowed recording of MeV-scale events. No signal candidates were found
First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA
The NOvA experiment has seen a 4.4σ signal of ν̄e appearance in a 2 GeV ν̄μ beam at a distance of 810 km. Using 12.33×1020 protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν̄μ→ν̄e candidates with a background of 10.3 and 102 ν̄μ→ν̄μ candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm322|=2.48-0.06+0.11×10-3 eV2/c4 and sin2θ23 in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δCP=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ23 values in the upper octant by 1.6σ
Measurement of the Double-Differential Muon-neutrino Charged-Current Inclusive Cross Section in the NOvA Near Detector
We report cross-section measurements of the final-state muon kinematics for
\numu charged-current interactions in the NOvA near detector using an
accumulated 8.09 protons-on-target (POT) in the NuMI beam. We
present the results as a double-differential cross section in the observed
outgoing muon energy and angle, as well as single-differential cross sections
in the derived neutrino energy, , and square of the four-momentum
transfer, . We compare the results to inclusive cross-section predictions
from various neutrino event generators via calculations using a
covariance matrix that accounts for bin-to-bin correlations of systematic
uncertainties. These comparisons show a clear discrepancy between the data and
each of the tested predictions at forward muon angle and low , indicating
a missing suppression of the cross section in current neutrino-nucleus
scattering models
Search for multimessenger signals in NOvA coincident with LIGO/Virgo detections
Using the NOvA neutrino detectors, a broad search has been performed for any signal coincident with 28 gravitational wave events detected by the LIGO/Virgo Collaboration between September 2015 and July 2019. For all of these events, NOvA is sensitive to possible arrival of neutrinos and cosmic rays of GeV and higher energies. For five (seven) events in the NOvA Far (Near) Detector, timely public alerts from the LIGO/Virgo Collaboration allowed recording of MeV-scale events. No signal candidates were found
An Improved Measurement of Neutrino Oscillation Parameters by the NOvA Experiment
We present new , ,
, and
oscillation measurements by
the NOvA experiment, with a 50% increase in neutrino-mode beam exposure over
the previously reported results. The additional data, combined with previously
published neutrino and antineutrino data, are all analyzed using improved
techniques and simulations. A joint fit to the , ,
, and candidate samples within the
3-flavor neutrino oscillation framework continues to yield a best-fit point in
the normal mass ordering and the upper octant of the mixing
angle, with eV and
. The data disfavor combinations of
oscillation parameters that give rise to a large asymmetry in the rates of
and appearance. This includes values of the
CP-violating phase in the vicinity of which are
excluded by for the inverted mass ordering, and values around
in the normal ordering which are disfavored at
2 confidence.Comment: 11 pages, 6 figures. Supplementary material attached (7 figures
Measurement of the Nucleus Charged-Current Double-Differential Cross Section at 2.4 GeV using NOvA
The inclusive electron neutrino charged-current cross section is measured in
the NOvA near detector using protons-on-target (POT) in the
NuMI beam. The sample of GeV electron neutrino interactions is the largest
analyzed to date and is limited by 17\% systematic rather than the
7.4\% statistical uncertainties. The double-differential cross section
in final-state electron energy and angle is presented for the first time,
together with the single-differential dependence on (squared
four-momentum transfer) and energy, in the range 1 GeV 6 GeV.
Detailed comparisons are made to the predictions of the GENIE, GiBUU, NEUT, and
NuWro neutrino event generators. The data do not strongly favor a model over
the others consistently across all three cross sections measured, though some
models have especially good or poor agreement in the single differential cross
section vs.
Extended search for supernova-like neutrinos in NOvA coincident with LIGO/Virgo detections
A search is performed for supernova-like neutrino interactions coincident
with 76 gravitational wave events detected by the LIGO/Virgo Collaboration. For
40 of these events, full readout of the time around the gravitational wave is
available from the NOvA Far Detector. For these events, we set limits on the
fluence of the sum of all neutrino flavors of at 90% C.L. assuming energy and time distributions
corresponding to the Garching supernova models with masses
9.6(27). Under the hypothesis that any given gravitational
wave event was caused by a supernova, this corresponds to a distance of kpc at 90% C.L. Weaker limits are set for other gravitational wave
events with partial Far Detector data and/or Near Detector data.Comment: 10 pages, 2 figure
Supernova neutrino detection in NOvA
The NOvA long-baseline neutrino experiment uses a pair of large, segmented, liquid-scintillator calorimeters to study neutrino oscillations, using GeV-scale neutrinos from the Fermilab NuMI beam. These detectors are also sensitive to the flux of neutrinos which are emitted during a core-collapse supernova through inverse beta decay interactions on carbon at energies of O(10 MeV). This signature provides a means to study the dominant mode of energy release for a core-collapse supernova occurring in our galaxy. We describe the data-driven software trigger system developed and employed by the NOvA experiment to identify and record neutrino data from nearby galactic supernovae. This technique has been used by NOvA to self-trigger on potential core-collapse supernovae in our galaxy, with an estimated sensitivity reaching out to 10 kpc distance while achieving a detection efficiency of 23% to 49% for supernovae from progenitor stars with masses of 9.6 M_⊙ to 27 M_⊙, respectively