Bulletin of the American Physical Society
2010 Fall Meeting of the APS Division of Nuclear Physics
Volume 55, Number 14
Tuesday–Saturday, November 2–6, 2010; Santa Fe, New Mexico
Session 2WA: Neutrinos and Fundamental Symmetries II |
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Chair: Takeyasu Ito, Los Alamos National Laboratory Room: Sweeny A |
Wednesday, November 3, 2010 9:00AM - 9:30AM |
2WA.00001: Nuclear Electric Dipole Moment Calculations Invited Speaker: One of the most important constraints on CP violation in the nucleon and NN interaction is provided by electric dipole moment (EDM) limits for neutral diamagnetic atoms, particularly 199Hg. To extract CP-violating couplings from experiment, one must relate the atomic EDM to the underlying nuclear CP-odd moments, a task complicated by the atomic response, which largely shields the nucleus from the applied external electric field. The residual response -- the Schiff moment -- depends on corrections such as the finite size of the nucleus. Conventional Schiff-moment calculations have largely ignored one consequence of the screening: the cancellation between direct and polarization diagrams, which yields an answer that is suppressed by two powers of RN/RA, where RN and RA are the nuclear and atomic sizes, requires one to identify all other terms that contribute to the same order in the RN/RA power counting. We show that such terms arise from nuclear excitations associated with the dipole charge and transverse electric multipole operators, and discuss the consequences. We also describe higher T-odd moments that contribute up to the same order in the counting, and point out interesting nuclear structure and experimental consequences. [Preview Abstract] |
Wednesday, November 3, 2010 9:30AM - 10:00AM |
2WA.00002: Search for a permanent electric dipole moment of mercury atoms Invited Speaker: Experimental searches for permanent electric dipole moments (EDMs) provide extremely sensitive probes for physics beyond the standard model. The three main classes of EDM searches are: measurements on bare neutrons; measurements on paramagnetic atoms or molecules, mainly sensitive to the electron EDM; and measurements on diamagnetic atoms, mainly sensitive to CP-violating interactions between nucleons. The most sensitive diamagnetic experiment is performed on Hg-199 atoms at the University of Washington in Seattle. A four vapor-cell measurement of the Hg EDM was recently completed, resulting in an upper bound $\vert$ d(Hg) $\vert <$ 3.1x10$^{-29}$ e cm, a factor of seven improvement on the previous limit. Details on the experimental technique and results will be given, along with theoretical implications of the new limit, and prospects for improvement. [Preview Abstract] |
Wednesday, November 3, 2010 10:00AM - 10:30AM |
2WA.00003: Muons and Fundamental Symmetries Invited Speaker: A sophisticated series of high-precision experiments involving muons is ongoing worldwide and many efforts have already produced exciting results. The physics addressed is broad, but here we will mainly focus on experiments related to fundamental symmetries. They include establishing parameters: Fermi constant, weak-nucleon pseudoscalar coupling, Michel parameters; searching for physics beyond the standard model: g-2, charged lepton flavor violation; and---we will allow this thematic deviation---determination of the proton charged radius as probed by the muonic Lamb shift. I will report on these projects as well as others, which are in progress. [Preview Abstract] |
Wednesday, November 3, 2010 10:30AM - 11:00AM |
2WA.00004: COFFEE BREAK
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Wednesday, November 3, 2010 11:00AM - 11:30AM |
2WA.00005: Muons and Fundamental Symmetries Invited Speaker: In this talk, I provide a general overview of muon physics and the role it can play in uncovering the Physics that lies beyond the Standard Model of Particle Physics. I concentrate on precision measurements of the muon anomalous magnetic moments and searches for charged lepton-flavor violation, emphasizing relations to the Physics uncovered by neutrino oscillation experiments and to searches for new degrees of freedom at high energy colliders. [Preview Abstract] |
Wednesday, November 3, 2010 11:30AM - 12:00PM |
2WA.00006: MuLan, a part-per-million measurement of the positive muon lifetime Invited Speaker: We report the results from a part-per-million measurement of the positive muon lifetime $\tau_{\mu}$, and a commensurate determination of the Fermi constant G$_F$, by the MuLan Collaboration. The Fermi constant governs the rates of all weak interaction processes and, together with the fine structure constant $\alpha$ and the Z-boson mass M$_Z$, fixes the electroweak sector of the Standard Model. Additionally, precise knowledge of the free muon lifetime $\tau_{\mu}$ is necessary for interpreting the results from ongoing lifetime measurements of muonic hydrogen and deuterium atoms. The MuLan experiment was conducted at the Paul Scherrer Institute in Villigen, Switzerland using a pulsed surface muon beam, in-vacuum muon-stopping targets, and a large acceptance, finely segmented, fast timing, scintillator array. The scintillator pulses were recorded by 500~MHz, 8-bit waveform digitizers and stored by a high-speed data acquisition system. A total of $\sim$10$^{12}$ decay positrons from muon stops in both a magnetized iron alloy target and a crystal quartz target were recorded. Thorough studies were conducted of systematic effects from positron pulse pileup, muon spin rotation, and other sources. The measured lifetimes from the two different targets are in excellent agreement and together yield a measurement of $\tau_{\mu}$ to better than 1.3~ppm and a determination of G$_F$ to better than 0.8~ppm. [Preview Abstract] |
Wednesday, November 3, 2010 12:00PM - 12:30PM |
2WA.00007: Cooperative Monitoring of Reactors with Antineutrino Detectors Invited Speaker: The current state-of-the-art in antineutrino detection is such that it is now possible to monitor the operational status, power levels and fissile content of nuclear reactors in real-time at standoff distances of a few tens of meters, well outside of the reactor containment. This has been demonstrated at civilian power reactors in both Russia and the United States. In the last few years, the International Atomic Energy Agency has begun to consider the potential of this technology for its reactor safeguards regime. In this talk, I describe the state of the art for this application, and emphasize the natural overlap with ongoing efforts in fundamental physics to measure the oscillations of antineutrinos using reactor sources. [Preview Abstract] |
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