Bulletin of the American Physical Society
Annual Meeting of the APS Four Corners Section
Volume 60, Number 11
Friday–Saturday, October 16–17, 2015; Tempe, Arizona
Session I9: Nuclear Physics I |
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Chair: Michael Dugger, Arizona State University Room: PSF166 |
Saturday, October 17, 2015 11:00AM - 11:12AM |
I9.00001: Precise beta decay studies in the UCNB and Nab Experiments Aaron Sprow Neutron decay correlations are sensitive to Standard Model parameters, and constrain Beyond the Standard Model physics competitive with high energy experiments like those conducted at the Large Hadron Collider. The UCNB and Nab experiments are two programs designed to study beta decay correlation coefficients. The goal of UCNB, at the Los Alamos Neutron Science Center (LANSCE), is to determine the neutrino asymmetry in polarized ultracold neutron decay, $B$, to a relative precision of $\delta B/B = 1\times10^{-3}$. The aims of Nab, at the Spallation Neutron Source (SNS) in Oak Ridge, are to determine the electron-neutrino correlation term, $a$, to a relative precision of $\delta a/a = 1\times10^{-3}$, and the Fierz interference term for neutron beta decay, $b$, to an uncertainty of $\delta b \leq 3\times10^{-3}$. A precise measurement of $a$ will lead to a new precise determination of $\lambda \equiv g_{A}/g_{V}$, the ratio of axial to vector coupling constants, while measurements of $b$ and $B$ will set limits on BSM effects. Both experiments will utilize long magnetic spectrometers with highly segmented silicon detectors at each end to detect the coincident electron and proton from each decay event. A brief overview on the ongoing development work at LANSCE will be presented. [Preview Abstract] |
Saturday, October 17, 2015 11:12AM - 11:24AM |
I9.00002: DarkLight: A Search for Dark Photons Glenn Randall The DarkLight experiment will search for a theoretically proposed heavy photon, postulated to carry a dark sector force. Discovery of this particle could give vital clues to the nature of dark matter, explain the difference between the theoretical and measured values of the muon magnetic moment, and account for a positron excess that has been observed in the Milky Way. We will look for a resonance in virtual photon mass in a high precision measurement of the process $e^-p\rightarrow e^-p\ e^+e^-$, which would imply the existence of a heavy photon. This will be done using lepton trackers and a proton detector to reconstruct interactions of an intense electron beam on a gaseous hydrogen target. The final experiment proposes to take approximately 1 ab$^{-1}$ of data using a 100 MeV electron beam at the Low Energy Recirculator Facility at Jefferson Lab. Design testing and measurement of QED backgrounds will begin in summer 2016. In this talk, I will discuss the DarkLight experiment and its status. [Preview Abstract] |
Saturday, October 17, 2015 11:24AM - 11:48AM |
I9.00003: Quark Orbital Angular Momentum Invited Speaker: Matthias Burkardt Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering. [Preview Abstract] |
Saturday, October 17, 2015 11:48AM - 12:00PM |
I9.00004: The OLYMPUS Experiment Lauren Ice The goal of the OLYMPUS experiment is to determine the multiple-photon exchange contribution to elastic lepton-proton scattering, the most likely candidate to resolve the disagreement between measurements of the electric to magnetic form factor ratio of the proton, obtained through polarization techniques, with those determined using the Rosenbluth separation technique. About 4 fb\(^{-1}\) of data were taken using electron and positron beams of 2.01 GeV energy incident on an unpolarized hydrogen target. The analysis effort is in an advanced state over the full acceptance range of \(0.6 \lt \mathrm{Q}^2 \lt 2.6\) (GeV/c)\(^2\). This talk will cover the motivation, experiment, and current status of the analysis. [Preview Abstract] |
Saturday, October 17, 2015 12:00PM - 12:12PM |
I9.00005: Determination of T and F observables in eta photoproduction on the CLAS Frozen Spin Target (FroST) Ross Tucker Polarization observables are an important tool for understanding and clarifying baryon resonance spectra. Recently, experiments were conducted at Jefferson Lab using a polarized photon beam incident on a polarized frozen spin target (FROST). The data used in the present analysis were taken during the second running period of FROST using the CLAS detector at Jefferson Lab, which utilized transversely polarized protons in a butanol target and an incident tagged photon energy between 0.62 and 2.93 GeV. We present preliminary data of the $T$ and $F$ asymmetries for $\eta$ photoproduction from the proton, along with comparisons to theoretical predictions. [Preview Abstract] |
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