Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session G12: Neutrino Physics A |
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Sponsoring Units: DPF Chair: Gregory Pawloski, Fermi National Accelerator Laboratory Room: Virginia A |
Sunday, February 14, 2010 8:30AM - 8:42AM |
G12.00001: Measuring Antineutrino Disappearance at MINOS using a NuMI Antineutrino Beam Alexander Himmel The NuMI beam-line was recently reconfigured to produce a primarily $\bar\nu_\mu$-beam by reversing the current in its two focusing horns. With an exposure $1 \times 10^{20}$ protons-on-target we can measure $\Delta\bar{m}_{23}^{2}$ to a precision of $25\%$ at maximal mixing at $90\%$ confidence, more than a factor of 3 improvement over current combined world limits. It is also a significant improvement on MINOS' own measurement of $\bar\nu_\mu$ oscillation parameters using the small $\bar\nu_\mu$ component of the primarily $\nu_\mu$ beam. The measurement will take advantage of MINOS' two magnetized steel-scintillator detectors and their unique ability to distinguish positive and negative muons and thus separate charged current neutrino and antineutrino interactions event-by-event. [Preview Abstract] |
Sunday, February 14, 2010 8:42AM - 8:54AM |
G12.00002: Measuring Neutrino Oscillations in MINOS Stephen Coleman The Main Injector Neutrino Oscillation Search (MINOS) is a two detector experiment in the NuMI muon neutrino beam. It is designed to measure muon neutrino disappearance after traveling 734km through the Earth. The survival probability of the oscillation hypothesis for neutrino disappearance is L/E dependent, so with a fixed L an energy-dependent muon neutrino disappearance measurement allows precision determination of neutrino oscillation parameters $\sin^{2} (2\theta_{23})$ and $\Delta m_{32}^{2}$. Other exotic disappearance hypotheses are also tested. We present techniques developed to improve our sensitivity compared to previous analyses. These include improving our beam extrapolation from the Near Detector to the Far Detector, the determination of backgrounds, and systematic uncertainties. We are also including information from additional datasets, such as anti-neutrino oscillations and muons from beam neutrino interactions in the rock upstream from the Far Detector. These techniques will be used to analyze data obtained from an accumulated $7.2\times 10^{20}$ protons on target, which is about twice the size of the previously analyzed dataset. [Preview Abstract] |
Sunday, February 14, 2010 8:54AM - 9:06AM |
G12.00003: Measuring Antineutrino Oscillations in MINOS Zeynep Isvan MINOS previously reported the first results of $\bar{\nu}_{\mu}$ disappearance from a direct observation of accelerator based muon antineutrinos in a long baseline experiment. The 7\% antineutrino component of the NuMI beam was used and a high purity sample of antineutrinos was selected at both the Near and Far Detectors. Selection efficiency at the Far Detector was 83\% and the purity of the selected $\bar{\nu}_{\mu}$ CC sample was 97\%. With this sample MINOS exludes a previously allowed CPT violating region of $\Delta\bar{m}^{2}_{atm}$ at maximal mixing and constrains the fraction of $\nu_{\mu}$ that disappear and reappear as $\bar{\nu}_{\mu}$. We present new measurements of $\bar{\nu}_{\mu}$ oscillation parameters and of the $\nu_{\mu} \rightarrow \bar{\nu}_{\mu}$ transition probability using the muon antineutrino spectra based on a larger data sample. [Preview Abstract] |
Sunday, February 14, 2010 9:06AM - 9:18AM |
G12.00004: The MINOS Electron Neutrino Appearance Analysis: Far Detector Background Prediction and Sensitivity to Theta13 Lisa Whitehead The MINOS experiment will attempt to constrain the value of $\theta_{13}$ by searching for electron neutrino appearance in our far detector with an exposure of 7e20 protons-on-target, more than double the data used in our previous analysis. This talk will describe the prediction of the background in the far detector based on near detector data and the systematic uncertainties in that prediction. Our sensitivity to $\theta_{13}$, which is enhanced due to both increased statistics and improved analysis techniques, will be discussed. [Preview Abstract] |
Sunday, February 14, 2010 9:18AM - 9:30AM |
G12.00005: Progress Towards an Updated MINOS Oscillation Parameter Analysis Jasmine Ratchford MINOS is a long baseline neutrino oscillation experiment composed of two detectors on the NuMI beam. The MINOS detectors are located at Fermilab in Batavia, IL and in the Soudan Mine near Ely Mn, 734 km apart. The NuMI beam, which originates at Fermilab is composed mainly of muon neutrinos. The MINOS Charged Current Analysis measures the mixing parameters $sin^{2}2\theta_{23}$and $\Delta m^{2}$ from $\nu_{\mu}$ disappearance in the NuMI beam. The 2008 MINOS measurement was based on 3.2E20 protons on the NuMI target. The next analysis will be based on an exposure of 7.2E20 protons on target. This talk summarizes progress toward the 2010 measurement, including data-driven measurements of the NC background, and low energy efficiency improvements through new identification parameters. The next analysis will explore the inclusion both neutrinos and anti-neutrinos in the data sample, and the inclusion rock muon events. [Preview Abstract] |
Sunday, February 14, 2010 9:30AM - 9:42AM |
G12.00006: Investigating CPT Conservation in Sterile Neutrino Fits Christina Ignarra We investigate compatibility between neutrino and antineutrino short-baseline oscillation experiments under a two-neutrino oscillation hypothesis due to a sterile neutrino at $ \Delta m^{2}\sim 1 eV^{2}$. We explore the preliminary MINOS antineutrino disappearance results as well as antineutrino oscillation results from LSND, MiniBooNE, KARMEN, Bugey, and Chooz, and neutrino oscillation results from NOMAD, MiniBooNE, CCFR84, and CDHS. We find that a combined fit of the antineutrino data yields a high chi-squared probability, while the global fit including neutrino and antineutrino data yields high incompatibility. CPT-violating fits within this scenario are also explored. [Preview Abstract] |
Sunday, February 14, 2010 9:42AM - 9:54AM |
G12.00007: Reconstructing Neutrino Interactions in MINERvA Benjamin Ziemer MINER$\nu$A is a high-statistics neutrino scattering experiment at Fermilab National Laboratory. The detector will be exposed to about $4e20$ protons on target (POT) from the NuMI beamline starting early 2010. Before the FNAL shutdown in Spring '09, the MINER$\nu$A Tracking Prototype (TP) detector collected neutrino events from $10^{19}$ POT. This detector was comprised about 20\% of the full MINER$\nu$A detector: a heavy nuclear target, twenty tracking planes, the full electromagnetic calorimeter and a reduced hadronic calorimeter. The fine grained nature of the detector yields coordinate residuals of 3.3mm, angular residuals of less than a degree and vertex residuals on the order of 4-6mm. Event topologies such as long muon tracks, short protons from both charged and neutral current reactions, multi-track pion production and inelastic showers have been seen in the data and have to be properly handled. This TP data is being used to finalize the reconstruction algorithms. I will review the current reconstruction program and the plans for its future application to full MINER$\nu$A data. [Preview Abstract] |
Sunday, February 14, 2010 9:54AM - 10:06AM |
G12.00008: A Search for Nuetrino Induced NC Coherent $\pi^{0}$ Production in the MINOS Near Detector Daniel Cherdack The production of single, highly forward $\pi^{0}$ mesons by neutral current (NC) coherent neutrino-nucleus interactions $\left( \nu_{\mu} + N \to \nu_{\mu} + N + \pi^{0}\right) $ is of current interest as a process amenable to phenomenological description, and as a potential background for long base-line $\nu_{\mu} \to \nu_{e}$ oscillation searches. The high-statistic sample of neutrino interactions recorded by the MINOS Near Detector (ND), a coarse-grained iron-scintillator tracking calorimeter, in the $E_{\nu}$ = 2-30 GeV range provide an opportunity to measure the cross-section of this coherent reaction on a relatively high-A nucleus. A major challenge to this measurement is the isolation of forward-going electromagnetic (EM) showers produced by the relatively rare NC coherent process from the abundance of incoherently produced EM showers. These backgrounds result from single $\pi^{0}$ dominated NC resonance and DIS events and by quasi-elastic-like charged-current scattering of electron neutrinos. The methods for event selection, error estimation, and signal extraction will be presented. [Preview Abstract] |
Sunday, February 14, 2010 10:06AM - 10:18AM |
G12.00009: Searching for Majorana Neutrinos in the Like-Sign Dilepton Final State Warren Clarida The Standard Model can be extended to include massive neutrinos as observed in the recent oscillation experiments. Perhaps the most commonly studied model is the type-I seesaw mechanism. This model introduces a new neutrino with a Majorana nature with an unknown mass. In this study we present the potential for the discovery of a Majorana neutrino during the first year of data collection from the Large Hadron Collider. In the analysis we used muon triggers, muon isolation, jet energy corrections, b-tagging, and an examination of the combinatorial background. We conclude that the discovery potential can be reached in the first year of running at the LHC at 10 TeV startup collision energy with the CMS detector for the Majorana neutrino mass range near 100 GeV. [Preview Abstract] |
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