Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session J8: Accelerator Neutrino Results |
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Sponsoring Units: DPF Chair: JoAnne Hewett, SLAC National Accelerator Laboratory Room: Grand F |
Sunday, May 1, 2011 1:30PM - 1:42PM |
J8.00001: New Neutrino Oscillation Results from T2K James Imber I report on the latest neutrino oscillation results from T2K. T2K is an off-axis long baseline beam neutrino experiment currently in operation in Japan. The muon neutrino beam generated at the J-PARC facility in Tokai traverses 295km to the Super-Kamiokande detector near Kamioka. T2K is designed to probe neutrino mixing and in particular to make high precision measurements of $\Delta m_{23}^2 $ and$\sin ^2\left( {2\theta _{23} } \right)$ and discover or set a greatly improved limit on $\sin ^2\left( {2\theta _{13} } \right)$ determined from the disappearance of muon neutrinos from the beam and the appearance of electron neutrinos. The first data set, the result of 3.23$\times $10$^{19}$ protons on target, was collected between January and June 2010. A summary of the observed event candidates in Super-Kamiokande is presented, illustrated with some distributions of selection variables. [Preview Abstract] |
Sunday, May 1, 2011 1:42PM - 1:54PM |
J8.00002: Neutrino-induced charged-current neutral pion (CCpi0) production in the P0D in the T2K experiment Daniel Ruterbories The T2K experiment is a second-generation long-baseline neutrino oscillation experiment designed to search for the appearance of electron neutrinos in a muon-neutrino beam. The PiZero sub-detector (P0D) of the T2K off-axis near detector ND280 is used to characterize the neutrino beam and to measure neutrino cross-sections. The T2K narrow-band beam peaks at $\sim $600 MeV, where experimental knowledge of these cross-sections is limited. The CCpi0 analysis can be used to better understand the neutral-current neutral pion (NCpi0) interaction, a major background for the electron-neutrino appearance measurement. I will give an overview of the CCpi0 interaction in this energy region and present the current status of the ongoing data analysis. [Preview Abstract] |
Sunday, May 1, 2011 1:54PM - 2:06PM |
J8.00003: Measurement of Neutral Current Pi 0 Cross Section using T2K ND280 Pi 0 Detector Karin Gilje, Glenn Lopez The T2K experiment is a long baseline neutrino experiment designed to directly measure $\nu_\mu\;\rightarrow\;\nu_e$ oscillation, thereby provide a measurement of $\theta_{13}$, the last unknown neutrino mixing angle. To achieve this goal, a beam of muon neutrinos is produced at the Japanese Proton Accelerator Research Complex (JPARC) in Tokai-Mura, Japan and sent 295 kilometers across Japan towards the Super-Kamiokande detector. One of the major backgrounds of the $\nu_e$ appearance measurement is from the production of $\pi^0$s from the neutral current $\nu_\mu$ interactions where the photons from the $\pi^0$ decay mimic the $\nu_e$ appearance signal. In order to constrain the uncertainty on this background, a $\pi^0$-detector (P$\O$D) has been designed and installed as part of the T2K near detector at 280 meters from the beam origin (ND280). The P$\O$D is designed specifically to measure the neutral current $\pi^0$ production cross section on water. In this talk, we present the details of this measurement. [Preview Abstract] |
Sunday, May 1, 2011 2:06PM - 2:18PM |
J8.00004: Analysis of muon anti-neutrino disappearance with the MINOS Detectors and the NuMI Beamline R. Benton Pahlka I will present an analysis of muon anti-neutrino ($\bar{\nu}_{\mu}$) disappearance using the MINOS detectors and a neutrino beam produced by the Fermilab Main Injector. The data were collected when the neutrino beamline was operated to produce muon neutrinos, with a 7\% component of muon anti-neutrinos. MINOS has accumulated an exposure of 7.1e20 protons on target (POT) in muon neutrino ($\nu_{\mu}$) mode and we reported a preliminary analysis of $\bar{\nu}_{\mu}$ oscillations with that dataset. We have also reported an analysis of $\bar{\nu}_{\mu}$ oscillations after an exposure of 3.2e20 POT. An improved analysis of the full 7.1e20 POT dataset is now being finalized. I will describe the analysis procedure, including selection of $\bar{\nu}_{\mu}$ charged current interactions, treatment of background from $\nu_{\mu}$ charged current interactions, prediction of event yields at the far detector, and the measurement of oscillation parameters. [Preview Abstract] |
Sunday, May 1, 2011 2:18PM - 2:30PM |
J8.00005: A Study of the Neutrino Mass Hierarchy with MINOS Far Detector Atmospheric Neutrinos Xinjie Qiu MINOS is a long-baseline neutrino oscillation experiment utilizing the NuMI neutrino beam from Fermilab. Although not designed for atmospheric neutrino analyses, the uniqueness of the MINOS magnetized detector enables neutrino induced muon charge discrimination and the measurement of the charge asymmetry due to matter effects as a function of zenith angle and neutrino energy. The oscillation probabilities are significantly modified by matter effects due to a coherent charged-current forward scattering of electron-type neutrinos with electrons as the neutrinos propagate through the Earth. The matter effects have an opposite sign for neutrinos versus antineutrinos and for the normal versus inverted neutrino mass hierarchy. We present in this talk an analysis of using the MINOS far detector atmospheric neutrinos for the potential neutrino mass hierarchy determination. A realistic analysis for atmospheric neutrinos is performed with simulated data. A Feldman-Cousins method is used to obtain the best fit and 90\% C.L. in the $sign(\Delta m^2) \cdot sin^2(2\theta_{13})$ space. [Preview Abstract] |
Sunday, May 1, 2011 2:30PM - 2:42PM |
J8.00006: Measuring Antineutrino Oscillations in MINOS Richa Sharma MINOS has previously reported the results of $\bar{\nu}_{\mu}$ disappearance from a direct observation of muon antineutrinos. The antineutrinos studied for this purpose are taken from two types of beam configurations: (a) Forward Horn Current (FHC), optimized for ${\nu}_{\mu}$ selection where the $\bar{\nu}_{\mu}$ content is 7\% of the neutrino beam, and (b) Reverse Horn Current (RHC), optimized for $\bar{\nu}_{\mu}$ selection where the $\bar{\nu}_{\mu}$ content is 40\% of the beam. The previous analyses were based on 3.2e20 protons on the NuMI target in FHC configuration and 1.7e20 protons on target in RHC configuration. These analyses make a precise measurement of the oscillation parameters $\Delta\bar{m}^{2}_{23}$ and $sin^{2}2\bar\theta_{23}$ and also constrain the fraction of ${\nu}_{\mu}$ that oscillate to $\bar{\nu}_{\mu}$. In the present analysis we have an FHC $\bar{\nu}_{\mu}$ data sample with 7.1e20 protons on target which will be used to improve the previous measurements. This talk summarizes the agreement between data and simulation in the Near Detector at Fermilab. [Preview Abstract] |
Sunday, May 1, 2011 2:42PM - 2:54PM |
J8.00007: A search for short-baseline muon neutrino disappearance with MiniBooNE and SciBooNE Kendall Mahn Neutrino mixing is consistent with three generations of neutrinos and a unitary mixing matrix. However, there is tension between the LSND experiments result of antineutrino oscillation at short baseline and the lack of such observation with the analogous result of the MiniBooNE experiment with neutrinos, indicating a possible third $\Delta m^2$ around 1$eV^2$ due to more than three neutrino generations or other exotic physics. A complementary way to access the same physics as $\nu_e$ appearance is $\nu_{\mu}$ disappearance. The MiniBooNE-only $\nu_{\mu}$ and $\overline{\nu}_{\mu}$ disappearance search was limited by flux and cross section uncertainties, which are reduced with the addition of data from the SciBooNE experiment, also present in the Fermilab Booster Neutrino beamline. This talk will describe the current picture of short-baseline neutrino disappearance, the flux constraint provided by SciBooNE, and the status of the joint MiniBooNE-SciBooNE analysis. [Preview Abstract] |
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