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 HJ: Mini-Symposium on Parity Violation and Fundamental Symmetries III |
Hide Abstracts |
Chair: Roger Carlini, Thomas Jefferson National Accelerator Facility Room: Coronado |
Friday, October 30, 2015 8:30AM - 9:06AM |
HJ.00001: Status and Prospects of Electric Dipole Moment Measurements Invited Speaker: Vince Cianciolo Precision electric dipole moment (EDM) measurements are extremely sensitive to non-Standard Model sources of charge/parity violation required for generation of the observed matter/anti-matter asymmetry in the universe. Many experiments in many systems are underway. In a half-hour talk it is difficult to do more than scratch the surface, but I will attempt to give a high-level overview on the various ongoing efforts. [Preview Abstract] |
Friday, October 30, 2015 9:06AM - 9:18AM |
HJ.00002: Nuclear Spin Dependent Parity Violation in Diatomic Molecules Sidney Cahn, Emine Altuntas, Jeffrey Ammon, David DeMille Nuclear spin-dependent parity violation (NSD-PV) effects arise from the exchange of the $Z^{0}$ boson between electrons and the nucleus and from the interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The anapole moment grows~as $A^{2/3~}$of the nucleus,while the $Z^{0}$ coupling is independent of $A$. We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. Using a Stark-interference technique, we measure the NSD-PV interaction matrix element. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system~$^{\mathrm{138}}$Ba$^{\mathrm{19}}$F. We also discuss improvements on investigations of systematics due to non-reversing stray $E$-fields, $E_{nr}$~together with~$B$-field inhomogeneities, and short-term prospects for measuring the nuclear anapole moment of $^{\mathrm{137}}$Ba. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei. [Preview Abstract] |
Friday, October 30, 2015 9:18AM - 9:30AM |
HJ.00003: Model Sensitivities in the Extraction of Q$_w$(p) from PVES Data Gregory Smith As the Q$_{\rm weak}$ collaboration prepares to unblind our final result, studies have been performed to quantify the sensitivities of the fit used to extract the proton's weak charge Q$_{\rm w}$(p) from the body of existing parity-violating electron scattering (PVES) data. The results of these sensitivity studies will be used to freeze choices associated with the fitting procedure before unblinding. Under study are the effects of including PVES data on D2 and He targets in the fit, and restrictions on the angular and Q$^2$ range of the data in the fit. The impact of different electromagnetic form factor (EM FF) fits, and the separate impact of the uncertainties associated with the EM FF fits themselves on the fit used to extract Q$_{\rm w}$(p) from the body of (mostly) $\vec{e}$p data have been studied. The impact of recent lattice QCD calculations of charge symmetry effects on our fit result will be assessed. A comparison will be made using recent lattice calculations of $\rho_s$ and $\mu_s$ in our Q$_{\rm w}$(p) determination, or floating these parameters in our fit. The dipole mass sensitivity in the strange and axial FFs will be assessed. The impact of floating the isoscalar and/or isovector axial FFs to theory or floating them freely in the fit will also be studied. [Preview Abstract] |
Friday, October 30, 2015 9:30AM - 9:42AM |
HJ.00004: The MOLLER Experiment - Parity-Violating M{\o}ller Scattering at Jefferson Lab Krishna Kumar The MOLLER experiment at Jefferson Lab will measure the parity-violating asymmetry $A_{PV}$ in polarized electron-electron (M{\o}ller) scattering. An 11 GeV, 90\% longitudinally polarized electron beam with a current of 60 ${\mu}$A will be incident on a 1.5 m liquid hydrogen target. A novel two-toroid spectrometer will focus small angle scattered electrons onto an array of 224 quartz {\^C}erenkov detectors 28 m downstream of the target center. The expected $A_{PV}$ is 33 parts per billion (ppb) with an overall precision goal of 0.7 ppb. This corresponds to $\sim 0.1\%$ precision on the weak mixing angle, matching the precision of the single best collider determinations and yielding the most precise measurement at low or high energy anticipated over the next decade. This result is sensitive to the interference of the electromagnetic amplitude with new neutral current amplitudes as weak as $10^{-3} G_F$. The resulting new physics discovery reach is unmatched by any proposed experiment measuring a flavor-, CP-conserving process over the next decade and yields a unique window to new physics at MeV and multi-TeV scales, complementary to direct searches at high energy colliders. A brief overview of the physics potential and design status of the experiment will be presented. [Preview Abstract] |
Friday, October 30, 2015 9:42AM - 9:54AM |
HJ.00005: Characterization of Systematic Effects in a Measurement of the Free Neutron Lifetime Using the UCN$\tau$ Magneto-Gravitational Trap A.T. Holley Measurement of the free neutron lifetime with a precision on the order of 1~s (0.1\%) has been demonstrated to be experimentally feasible, but the current uncertainty in our knowledge of the neutron lifetime is significantly poorer, dominated by a nearly 8~s ($4\sigma$) discrepancy between two complementary measurement techniques: the slow-neutron ``beam'' approach and the ``bottle'' method, which measures the number of surviving ultracold neutrons (UCN) following storage in a suitable trapping potential. The UCN$\tau$ collaboration has constructed a large-volume magneto-gravitational trap expected to reduce systematic effects associated with previous bottle measurements, which utilized material traps and external UCN detectors. Our strategy eliminates material interactions during UCN storage using permanent NdFeB magnets in a bowl-shaped Halbach configuration to trap UCN from the sides and below, and the earth's gravitational field to trap them from above. Surviving UCN are counted using an \textit{in situ} integrating activation detector that rapidly absorbs UCN in the trap. Ongoing efforts to investigate the residual systematic effects associated with our experimental configuration will be discussed. [Preview Abstract] |
Friday, October 30, 2015 9:54AM - 10:06AM |
HJ.00006: Determination of $Q_{\mathrm{EC}}$ values of $T=1/2$ mirror nuclei at LEBIT Martin Eibach, Georg Bollen, Maxime Brodeur, Kortney Cooper, Kerim Gulyuz, Chris Izzo, David Morrissey, Matthew Redshaw, Ryan Ringle, Rachel Sandler, Stefan Schwarz, Chandana Sumithrarachchi, Adrian Valverde, Antonio Villari The ongoing search for evidence of physics beyond the standard model is one of the driving forces in fundamental physics research. Particularly crucial for testing the validity of the electroweak model is the unitarity of the Cabibbo-Kobayashi-Maskawa matrix. The most stringent test is the verification of the first row condition $V^2_{ud}+V^2_{us}+V^2_{ub}=1$. Therefore, the dominating element, $V_{ud}$, has to be determined with high precision. Complementary methods are measurements of the free neutron lifetime, pion decay rates, superallowed decay properties of $T=1$ nuclei and the newer approach of decay property measurements of $T=1/2$ isospin doublets. In the latter two approaches $V_{ud}$ is determined via $\mathcal{F}$t values to which the transition energy $Q_{\mathrm{EC}}$ contributes in the fifth power. We report the first high-precision measurement of $Q_{\mathrm{EC}}$ of the mixed Fermi-Gamow-Teller decays of the three T=1/2 nuclei $^{11}$C, $^{21}$Na and $^{29}$P. The uncertainties of all values were reduced significantly and their contribution to $V_{ud}$ thereby reduced the same order as the theoretical uncertainties. [Preview Abstract] |
Friday, October 30, 2015 10:06AM - 10:18AM |
HJ.00007: Search for new physics in a precise $^{20}$F beta spectrum shape measurement Elizabeth George, Paul Voytas, Thomas Chuna, Oscar Naviliat-Cuncic, Alexandra Gade, Max Hughes, Xueying Huyan, Sean Liddick, Kei Minamisono, Stanley Paulauskas, Dirk Weisshaar, Gilles Ban, Xavier Flechard, Etienne Lienard We are carrying out a measurement of the shape of the energy spectrum of $\beta$ particles from $^{20}$F decay. We aim to achieve a relative precision below 3\%, representing an order of magnitude improvement compared to previous experiments. This level of precision will enable a test of the so-called strong form of the conserved vector current (CVC) hypothesis, and should also enable us to place competitive limits on the contributions of exotic tensor couplings in beta decay. In order to control systematic effects, we are using a technique that takes advantage of high energy radioactive beams at the NSCL to implant the decaying nuclei in a scintillation detector deep enough that the emitted beta particles cannot escape. The $\beta$-particle energy is measured with the implantation detector after switching off the beam implantation. Ancillary detectors are used to tag the 1.633-MeV $\gamma$-rays following the $\beta$ decay for coincidence measurements in order to reduce backgrounds. We will give an overview and report on the status of the experiment. [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