Over the last decade, there has been enormous effort to measure neutrino interaction cross sections important to oscillation experiments. However, a number of results from modern experiments appear ...to be in tension with each other, despite purporting to measure the same processes. The TENSIONS2016 workshop was held at University of Pittsburgh July 24–31, 2016 and was sponsored by the Pittsburgh Particle Physics, Astronomy, and Cosmology Center (PITT PACC). The focus was on bringing experts from three experimental collaborations together to compare results in detail and try to find the source of tension by clarifying and comparing signal definitions and the analysis strategies used for each measurement. A set of comparisons between the measurements using a consistent set of models was also made. This paper summarizes the main conclusions of that work.
We show that one may quantitatively investigate radiative broadening of atomic transitions in the undergraduate laboratory using a traditional saturated absorption spectroscopy setup.
Knowledge of the neutrino flux produced by the Neutrinos at the Main Injector (NuMI) beamline is essential to the neutrino oscillation and neutrino interaction measurements of the MINERvA, MINOS+, ...NOvA and MicroBooNE experiments at Fermi National Accelerator Laboratory. We have produced a flux prediction which uses all available and relevant hadron production data, incorporating measurements of particle production off of thin targets as well as measurements of particle yields from a spare NuMI target exposed to a 120 GeV proton beam. The result is the most precise flux prediction achieved for a neutrino beam in the one to tens of GeV energy region. We have also compared the prediction to in situ measurements of the neutrino flux and find good agreement.
We measure sub-MHz AC Stark shifts, also known as light shifts, in an undergraduate laboratory setting using Raman pump-probe spectroscopy to observe sub-natural linewidth spectral features in the ...transmission spectrum of a weak probe beam passing through a sample of cold 85Rb atoms confined in a magneto-optical trap. To make this observation a pair of inexpensive fast photodiodes and acousto-optic modulators is needed, in addition to equipment commonly found in advanced undergraduate optics labs with laser cooling and atom trapping setups. A theoretical description of light shifts accessible to junior and senior-level physics majors is provided.
Final-state kinematic imbalances are measured in mesonless production of νμ+A→μ-+p+X in the MINERvA tracker. Initial- and final-state nuclear effects are probed using the direction of the μ- - p ...transverse momentum imbalance and the initial-state momentum of the struck neutron. Differential cross sections are compared to predictions based on current approaches to medium modeling. These models underpredict the cross section at intermediate intranuclear momentum transfers that generally exceed the Fermi momenta. As neutrino interaction models need to correctly incorporate the effect of the nucleus in order to predict neutrino energy resolution in oscillation experiments, this result points to a region of phase space where additional cross section strength is needed in current models, and demonstrates a new technique that would be suitable for use in fine-grained liquid argon detectors where the effect of the nucleus may be even larger.
The semiexclusive channel νμ+CH→μ−π0+nucleon(s) is analyzed using MINERvA exposed to the low-energy NuMI νμ beam with spectral peak at Eν≃3 GeV. Differential cross sections for muon momentum and ...production angle, π0 kinetic energy and production angle, and for squared four-momentum transfer are reported, and the cross section σ(Eν) is obtained over the range 1.5 GeV≤Eν<20 GeV. Results are compared to GENIE and NuWro predictions and to published MINERvA cross sections for charged-current π+(π0) production by νμ(ν¯μ) neutrinos. Disagreements between data and simulation are observed at very low and relatively high values for muon angle and for Q2 that may reflect shortfalls in modeling of interactions on carbon. For π0 kinematic distributions, however, the data are consistent with the simulation and provide support for generator treatments of pion intranuclear scattering. Using signal-event subsamples that have reconstructed protons as well as π0 mesons, the pπ0 invariant mass distribution is obtained, and the decay polar and azimuthal angle distributions in the rest frame of the pπ0 system are measured in the region of Δ(1232)+ production, W<1.4 GeV.
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