Abstract: Radio-frequency (RF) carpets with ultra-fine pitches are examined for ion transport in gases at atmospheric pressures and above. We develop new analytic and computational methods for modeling RF ion transport at densities where dynamics are strongly influenced by buffer gas collisions. An analytic description of levitating and sweeping forces from phased arrays is obtained, then thermodynamic and kinetic principles are used to calculate ion loss rates in the presence of collisions. This methodology is validated against detailed microscopic SIMION simulations. We then explore a parameter space of special interest for neutrinoless double beta decay experiments: transport of barium ions in xenon at pressures from 1 to 10 bar. Our computations account for molecular ion formation and pressure dependent mobility as well as finite temperature effects. We discuss the challenges associated with achieving suitable operating conditions, which lie beyond the capabilities of existing devices, using presently available or near-future manufacturing techniques.

Abstract: New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter theta(23). Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57 x 10(20) protons on target, T2K has fit the energy-dependent nu(mu) oscillation probability to determine oscillation parameters. The 68% confidence limit on sin(2)(theta(23)) is 0.514(-0.056)(+0.055) (0.511 +/- 0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Delta m(32)(2) = (2.51 +/- 0.10) x 10(-3) eV(2)/c(4) (inverted hierarchy: Delta m(13)(2) = (2.48 +/- 0.10) x 10(-3) eV(2)/c(4)). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty.

Abstract: We report the first measurement of the flux-averaged cross section for charged current coherent pi(+) production on carbon for neutrino energies less than 1.5 GeV, and with a restriction on the final state phase space volume in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso et al., the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. We observe a clear event excess above background, disagreeing with the null results reported by K2K and SciBooNE in a similar neutrino energy region. The measured flux-averaged cross sections are below those predicted by both the Rein-Sehgal and Alvarez-Ruso et al. models.

Abstract: The T2K off-axis near detector ND280 is used to make the first differential cross-section measurements of electron neutrino charged current interactions at energies similar to 1 GeV as a function of electron momentum, electron scattering angle, and four-momentum transfer of the interaction. The total flux-averaged nu(e) charged current cross section on carbon is measured to be <sigma >(phi) = 1.11 +/- 0.10(stat) +/- 0.18(syst) x 10(-38) cm(2)/nucleon. The differential and total cross- section measurements agree with the predictions of two leading neutrino interaction generators, NEUT and GENIE. The NEUT prediction is 1.23 x 10(-38) cm(2)/nucleon and the GENIE prediction is 1.08 x 10(-38) cm(2)/nucleon. The total nu(e) charged current cross-section result is also in agreement with data from the Gargamelle experiment.