Bulletin of the American Physical Society
2015 Fall Meeting of the APS Division of Nuclear Physics
Volume 60, Number 13
Wednesday–Saturday, October 28–31, 2015; Santa Fe, New Mexico
Session CJ: Electroweak I |
Hide Abstracts |
Chair: Nadia Fomin, University of Tennessee Room: Coronado |
Thursday, October 29, 2015 8:30AM - 8:42AM |
CJ.00001: Ab-initio calculation of neutrino-carbon scattering in the quasi-elastic region Stefano Gandolfi Several upcoming experiments have the ambitious goal to understand neutrino mixing, including the mass hierarchy and CP violation, to search for physics beyond the standard model. These experiments aim to reach a precision at the per-cent level, and, in order to accurately interpret these measurements, the knowledge of the neutrino-nucleus interaction is critical. In this talk we will present recent Green's Function Monte Carlo calculations of the euclidean correlation functions that are relevant for the $\nu$-$^{12}$C scattering in the quasi-elastic region. These non-perturbative calculations fully include long- and short-range correlations in the nuclear wave function, and give an excellent description of properties of light nuclei. We will show that the inclusion of two-body operators consistent with the nuclear Hamiltonian is crucial and their contribution is quite sizable, as already predicted by similar calculations and experimental measurements of electron-scattering. These contributions are necessary to understand electron scattering and are also very important in neutrino-nucleus scattering. [Preview Abstract] |
Thursday, October 29, 2015 8:42AM - 8:54AM |
CJ.00002: Progress of the TREK/E36 Experiment at J-PARC Michael Kohl The TREK/E36 experiment is being carried out at J-PARC to provide a precision test of lepton universality in the $K_{e2}/K_{\mu2}$ ratio to search for new physics beyond the Standard Model. Simultaneously it will be sensitive to light U(1) gauge bosons and sterile neutrinos below 300 MeV/$c^2$, which could be associated with dark matter or explain established muon-related anomalies such as the muon $g-2$ and the proton radius puzzle. The experiment has been set up at the J-PARC K1.1BR kaon beamline since fall 2014, it has been fully commissioned in spring 2015, and is now ready to accumulate production data anticipated in fall 2015. It uses a scintillating fiber target to stop a beam of up to 1.2 Million $K^+$ per spill. The kaon decay products are detected with a large-acceptance toroidal spectrometer capable of tracking charged particles with high resolution, combined with a photon calorimeter with large solid angle and particle identification systems. The status and recent progress of the experiment will be presented. [Preview Abstract] |
Thursday, October 29, 2015 8:54AM - 9:06AM |
CJ.00003: Charge Symmetry Breaking Electromagnetic Nucleon Form Factors in Elastic Parity-Violating Electron-Nucleus Scattering Gerald A. Miller The effects of charge symmetry breaking in nucleon electromagnetic form factors on parity- violating elastic electron-12C scattering is studied, and found to be much smaller than other known effects. The analysis of a planned experiment is discussed. [Preview Abstract] |
Thursday, October 29, 2015 9:06AM - 9:18AM |
CJ.00004: Neutron Spin Rotation Measurement Churamani Paudel The neutron spin rotation (NSR) collaboration used Parity-violating spin rotation of transversely polarized neutrons Transmitted through a 0.5 m liquid helium target to constrain weak coupling constants between nucleons. While consistent with theoretical expectation, the upper limit set by this measurement on the rotation angle, d$\phi$/dz = [+1.7 $\pm$ 9.1(stat.) $\pm$1.4(sys.)]$\times 10^{-7}$ rad/m, is limited by statistical uncertainties. The NSR collaboration is preparing a new measurement to improve this statistically limited result by about an order of magnitude. In addition to using the new high-flux NG-C beam at the National Institute of Standards and Technology (NIST) Center for Neutron Research, the apparatus is being upgraded to take advantage of the Larger-area and more divergent NG-C beam. In addition, significant improvements have been made to the cryogenic design and the He-3 ion chamber. Details of these improvements and readiness of the upgraded apparatus will be discussed. [Preview Abstract] |
Thursday, October 29, 2015 9:18AM - 9:30AM |
CJ.00005: Simulations of Neutron Spin Rotation Measurements by the NSR Collaboration Bret Crawford The Neutron Spin Rotation (NSR) collaboration has developed an apparatus capable of measuring the rotation of transversely polarized neutrons to the level of a few times $10^{-7}$ rad/m to place limits on coupling constants of the hadronic weak interaction (HWI) and long-range exotic fifth forces [RSI 86, 055101 (2015)]. The NSR measurement of $d\phi/dz = \left[ +1.7 \pm 9.1 (stat.)\pm1.4(sys.)\right] \times 10^{-7}$ rad/m [PRC 83, 022501(R) (2011)] for neutrons in liquid-He constrains both HWI coupling constants and the strength of possible exotic parity-odd long-range interactions [PRL 110, 082003 (2013)]. Given the dependence of possible systematic effects on the neutron phase space, neutron transport, and interactions with the target, a Monte-Carlo transport code was developed to examine the size of possible false rotations and their dependence on beam/apparatus characteristics. In addition, the code has been adapted to determine the sensitivity of measurements with a new target designed to measure a parity-conserving rotation due to possible long-range interactions. Simulation results and a status of the current experiment to place limits on the axial-axial coupling of such a long-range interaction and efforts to improve the HWI limits in liquid helium will be presented. [Preview Abstract] |
Thursday, October 29, 2015 9:30AM - 9:42AM |
CJ.00006: Energy dependence of the parity-violating asymmetry of circularly polarized photons in $d\vec{\gamma} \to np$ in pionless effective field theory Jared Vanasse, Matthias Schindler At low energies parity-violating interactions between nucleons are described by five low energy constants. The aim of hadronic parity-violation is to cleanly obtain these from experiment, for which few-body systems and pionless effective field theory are ideally suited. In this talk I will discuss the calculation of the parity violating asymmetry in the cross sections for circularly polarized photons on an unpolarized deuteron target in $d\vec{\gamma} \to np$ using pionless effective field theory. Using this calculation with estimates for the parity-violating low energy constants I will show the ideal energy at which such an experiment should be performed. This experiment is of particular interest as it is a possible future experiment at an upgraded High Intensity Gamma-Ray Source at the Triangle Universities Nuclear Laboratory. [Preview Abstract] |
Thursday, October 29, 2015 9:42AM - 9:54AM |
CJ.00007: A Study of Hadronic Weak Interaction - The n$^{3}$He Experiment at SNS Latiful Kabir While parity violation (PV) is well-understood at the quark and lepton level, it is much more elusive in hadronic systems, being dominated by several orders of magnitude by the strong interaction. However, studies of PV in hadronic systems offer a unique probe of nucleon structure, complementary to other probes of low-energy non-perturbative QCD. The n$^{3}$He experiment at the spallation neutron source at ORNL is motivated to probe the Hadronic Weak Interaction (HWI) by measuring the parity violating spin asymmetry of the recoil proton in the reaction n$+$ $^{3}$He $\to $ p $+$T$+$765 KeV. This is sensitive to $\Delta $I $=$ 0 and 1 components of the HWI, and is expected to be extremely small (of the order of 10$^{-7}$). The experiment aims to determine this PV asymmetry with the statistical sensitivity of the order of 10$^{-8}$. The experiment is now in the data taking phase and will continue until the end of the year. I will describe the experiment and give its current status. [Preview Abstract] |
Thursday, October 29, 2015 9:54AM - 10:06AM |
CJ.00008: Status on the search for new currents in the beta decay of ultracold neutrons Kevin Hickerson There is growing interest in the search for new charged flavor changing currents not predicted by the Standard Model. The beta decay of neutrons is sensitive to tensor currents, for example, that are not ruled out by other systems without the need for nuclear correction calculations. These tensor currents alter beta-decay correlation coefficients, where, in particular, the Fierz interference term, $b$, becomes non-zero. We report on the status of understanding the systematic errors that dominated previous limits of the Fierz interference term for the free neutron, $b_n$, using ultracold neutrons (UCN), as measured using the UCNA experiment at the Los Alamos Neutron Science Center. UCNA was designed to measure the energy dependence of the electron beta decay asymmetry, $A(E)$, for different neutron polarizations, but $b_n$ can skew the peak of the beta spectrum and modify the energy dependence of the asymmetry, both measured by UCNA, so investigation of $b_n$ is possible. We will present how analysis of UCNA data collected from 2011-2013, paying close attention to systematic errors associated with energy calibration and linearity, may help improve present limits on $b_n$. We will also discuss other possible experimental approaches that may improve those limits further still. [Preview Abstract] |
Thursday, October 29, 2015 10:06AM - 10:18AM |
CJ.00009: UCNB and Nab Detector Development Bryan Zeck The UCNB and Nab experiments, designed to measure correlations in neutron beta decay, will detect the charged decay particles with segmented, large area, thick silicon detectors with thin dead layers. Development of the detector mount and the associated preamplifier and data acquisition system has been ongoing at Los Alamos National Laboratory using the LANSCE Ultracold Neutron facility. A 24 channel prototype preamplifier and data acquisition system has been demonstrated to meet performance specifications, including a 10 keV trigger threshold (required to detect the decay protons), a 3 keV FWHM particle kinetic energy resolution (required to measure the decay electron energy spectrum to sufficient accuracy), and a 40 ns pulse rise time (required to identify the direction of travel of decay electrons). Results of timing and coincidence studies, a report on progress to a fully instrumented detection system, and a final design for the detector mount compatible with the Nab experimental setup will be presented. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700