281 research outputs found
Microchannel avalanche photodiode with wide linearity range
Design and physical operation principles of new microchannel avalanche
photodiode (MC APD) with gain up to 10^5 and linearity range improved an order
of magnitude compared to known similar devices. A distinctive feature of the
new device is a directly biased p-n junction under each pixel which plays role
of an individual quenching resistor. This allows increasing pixel density up to
40000 per mm^2 and making entire device area sensitive.Comment: Submitted to Journal of Technical Physic
Extended search for supernovalike neutrinos in NOvA coincident with LIGO/Virgo detections
A search is performed for supernovalike 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 F29(50) kpc at 90% C.L. Weaker limits are set for other gravitational wave events with partial Far Detector data and/or Near Detector data
Search for active-sterile neutrino mixing using neutral-current interactions in NOvA
We report results from the first search for sterile neutrinos mixing with active neutrinos through a reduction in the rate of neutral-current interactions over a baseline of 810 km between the NOvA detectors. Analyzing a 14-kton detector equivalent exposure of 6.05 x 10(20) protons-on-target in the NuMI beam at Fermilab, we observe 95 neutral-current candidates at the Far Detector compared with 83.5 +/- 9.7(stat) +/- 9.4(syst) events predicted assuming mixing only occurs between active neutrino species. No evidence for upsilon(mu) -\u3e upsilon(mu) transitions is found. Interpreting these results within a 3 + 1 model, we place constraints on the mixing angles theta(24) \u3c 20.8 degrees and theta(34) \u3c 31.2 degrees at the 90% C.L. for 0.05 eV(2) \u3c= Delta m(41)(2) \u3c= 0.5 eV(2), the range of mass splittings that produce no significant oscillations over the Near Detector baseline
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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 ν μ charged-current interactions in the NOvA near detector using an accumulated 8.09×1020 protons on target 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, Eν, and square of the four-momentum transfer, Q2. We compare the results to inclusive cross-section predictions from various neutrino event generators via χ2 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 Q2, indicating a missing suppression of the cross section in current neutrino-nucleus scattering models
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First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA.
The NOvA experiment has seen a 4.4σ signal of ν[over ¯]_{e} appearance in a 2 GeV ν[over ¯]_{μ} beam at a distance of 810 km. Using 12.33×10^{20} protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν[over ¯]_{μ}→ν[over ¯]_{e} candidates with a background of 10.3 and 102 ν[over ¯]_{μ}→ν[over ¯]_{μ} candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm_{32}^{2}|=2.48_{-0.06}^{+0.11}×10^{-3}  eV^{2}/c^{4} and sin^{2}θ_{23} 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 δ_{CP}=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ_{23} values in the upper octant by 1.6σ
Measurement of the Neutrino Mixing Angle theta(23) in NOvA
This Letter reports new results on muon neutrino disappearance from NOvA, using a 14 kton detector equivalent exposure of 6.05 x 10(20) protons on target from the NuMI beam at the Fermi National Accelerator Laboratory. The measurement probes the muon-tau symmetry hypothesis that requires maximal theta(23) mixing (theta(23) = pi/4). Assuming the normal mass hierarchy, we find Delta m(32)(2) = (2.67 +/- 0.11) x 10(-3) eV(2) and sin(2) theta(23)at the two statistically degenerate values 0.404(-0.022)(+0.030) and 0.624(-0.030)(+0.022), both at the 68% confidence level. Our data disfavor the maximal mixing scenario with 2.6 sigma significance
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