Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session JG: Mini-symposium on Electric Dipole MomentsMini-Symposium
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Chair: Takeyasu Ito, Los Alamos National Laboratory Room: Pavilion Ballroom B |
Saturday, October 15, 2016 10:30AM - 11:06AM |
JG.00001: Search for Electric Dipole Moments Invited Speaker: Shinsuke Kawasaki Existence of a non-zero electric dipole moment (EDM) violates both parity (P) and time reversal (T). Assuming CPT invariance, T-violation means CP-violation. Within the standard model of physics, EDM is predicted to be much smaller value of current experiment sensitivity. Relatively large EDM value implies beyond standard model physics. Many experiments have been trying to measure EDM of fundamental particles such as electron, neutron and other. Although non- zero EDM value has not been found yet, upper limit of it set constraint on new physics theory. In this talk, current status of EDM search experiments will be discussed. [Preview Abstract] |
Saturday, October 15, 2016 11:06AM - 11:18AM |
JG.00002: Beyond Schiff Moment: Atomic EDMs from Two-Photon Exchange Satoru Inoue, Michael Ramsey-Musolf Interpretation of atomic EDM searches requires careful consideration of the Schiff theorem, which states that a neutral system of non-relativistic point charges interacting only electrostatically has zero net EDM. Atomic EDMs arise from breakdowns in the assumptions to the Schiff theorem. Conventionally, the leading contributions to EDMs of diamagnetic atoms are thought to be nuclear Schiff moments, which arise due to finite sizes of nuclei. We revisit the argument to derive the Schiff moment contribution to atomic EDMs and find that atomic EDMs can be generated from non-electrostatic interactions, namely 2 successive electron-nucleus interactions involving transverse electric multipoles. We estimate that this contribution can be comparable to the Schiff moment effect. [Preview Abstract] |
Saturday, October 15, 2016 11:18AM - 11:30AM |
JG.00003: Exotic physics by-products of neutron edm searches Beatrice Franke The search for the neutron electric dipole moment (edm) is a highly sensitive precision measurement. There are several efforts world-wide in order to search for this elusive quantity: predictions by the standard model of particle physics are $\sim$$10^{-32}\,e$cm. However, beyond standard model theories (BSM) predict much larger neutron edms, resulting from additional CP violating processes necessary to better understand the strong CP problem and in particular the baryon asymmetry observed in our universe. Some predictions are very close to the current upper limit of $3\cdot10^{-26}\,e$cm [1], and within "arm's reach" of ongoing experimental efforts. The involved highly sensitive setups also give access to investigate other intriguing beyond standard model predictions, as has been shown previously for mirror neutron oscillations [2], Lorentz violation [3], and axion-like particle searches [4], among others. A brief overview shall be given of what has been achieved so far in different experiments, as well as show which of those investigations could be of interest for upcoming neutron edm spectrometers. [1] Pendlebury et al. Phys Rev D 92 (2015) 092003 [2] Altarev et al. Phys Rev D 80 (2009) 032003 [3] Altarev et al. EPL 92 (2010) 51001 [4] Afach et al. PLB 745 (2015) 58 [Preview Abstract] |
Saturday, October 15, 2016 11:30AM - 11:42AM |
JG.00004: Upgrades for an improved measurement of the EDM of $^{\mathrm{\mathbf{225}}}$Ra. Tenzin Rabga, Kevin Bailey, Matthew R. Dietrich, John P. Greene, Roy J. Holt, Wolfgang Korsch, Zheng-Tian Lu, Peter Mueller, Tom P. O'Connor, Steven Fromm, Roy Ready, Jaideep T. Singh Electric Dipole Moment (EDM) searches provide a sensitive way for probing time-reversal symmetry (T) violation in the Universe that might explain the abundance of matter over anti-matter. The $^{\mathrm{225}}$Ra atom (t$_{\mathrm{1/2}} \quad =$ 15 days, I $=$ 1/2) is a particularly attractive candidate for an EDM experiment in diamagnetic atoms due to its octupole deformation, nearly degenerate parity doublet ground state, and large mass, that make it sensitive to T-violating interactions in the nuclear sector. Since our first measurement in 2015, we have improved the sensitivity of our apparatus by more than an order of magnitude to 1.4x10$^{\mathrm{-23}}$ e-cm (95{\%} C.L), due to improvements in the atom lifetime. Further experimental upgrades are being implemented including an electric field upgrade to enhance the EDM sensitivity and STIRAP for an improved spin precession detection scheme. With these upgrades in place our EDM sensitivity should increase by nearly two orders of magnitude and allow us to substantially improve constraints on certain T-violating processes within the nucleus.~ [Preview Abstract] |
Saturday, October 15, 2016 11:42AM - 11:54AM |
JG.00005: Status of the nEDM Experiment at PSI Matthew Musgrave The search for the neutron electric dipole moment (nEDM) is one of the most sensitive probes for new sources of T and CP violation, which could provide insight into important unanswered questions in the Standard Model including the baryon asymmetry of the universe and the strong CP problem. The current limit of the nEDM is dn $<$ 3.0E-26 ecm (90\% CL) [J. M. Pendlebury et al. PRD 92 092003 (2015)]. At the Paul Scherrer Institut (PSI) in Switzerland an international collaboration of 14 institutions intends to either discover an nEDM or improve this limit using a new solid deuterium ultracold neutron (UCN) source and an upgraded version of the RAL/Sussex/ILL apparatus. The experiment is currently in operation and has implemented a data blinding algorithm for future analysis. Additional milestones include a new technique to determine the UCN energy spectra using spin-echo, measurement of the ratio of the neutron and 199Hg gyromagnetic ratios to within 0.8 ppm, and improved limits on the axion phase-space by searching for an oscillating nEDM. The current status of the experiment and future plans will be discussed. [Preview Abstract] |
Saturday, October 15, 2016 11:54AM - 12:06PM |
JG.00006: A Plan for a Ten-fold Improvement of the Neutron Electric Dipole Moment with the LANL UCN Source Chen-Yu Liu, Steve Clayton, Scott Currie, Takeyasu Ito, Mark Makela, Chris Morris, Robert Pattie, John Ramsey, Andy Saunders, Zhaowen Tang, Josh Long, Mike Snow, Brad Plaster, S.K. Lamoreaux, E Sharapov The Electric Dipole Moment of the neutron is a probe for the violations in the combined Charge-conjugate and Parity-reversal symmetry. Many theories beyond the Standard Model, which aim to unify the fundamental forces and solve the problem of Baryon Asymmetry of the Universe, also predict sizable EDM just lurking around the corner for discovery. However, the low density of UCN limits the worldwide progress of current nEDM experiments; existing facilities have not been able to deliver significantly higher UCN flux. An opportunity exists in the LANL UCN facility: With an order of magnitude increase in the LANL UCN source intensity, one could realize a nEDM search at the 10$^{-27}$e-cm level of sensitivity soon. An upgrade to the LANL UCN facility is now underway; it will provide the UCN flux needed to meet the demand of this experiment. We will apply the Ramsey's separated oscillatory field method to measure the precession frequency of the neutron under a small, precisely controlled, static magnetic field. We will report the status and plan of the LANL nEDM experiment. [Preview Abstract] |
Saturday, October 15, 2016 12:06PM - 12:18PM |
JG.00007: ABSTRACT WITHDRAWN |
Saturday, October 15, 2016 12:18PM - 12:30PM |
JG.00008: Critical Spin Dressing Reza Tavakoli Dinani, Michael Hayden Magnetometry is critical to many experiments that test fundamental symmetries. It has long been proposed [1] that spin dressing [2] could be employed to realize a highly effective helium-3 nuclear precession co-magnetometer for a neutron electric dipole moment search. This would involve applying an intense, continuous, and far off-resonant oscillating magnetic field in such a way that the apparent Larmor precession frequency of both species is modified. Under appropriate conditions a desirable situation known as critical dressing is anticipated: the neutron and the helium-3 nucleus (or more generally, any two spin species) are expected to behave as if they had the same gyromagnetic ratio and hence should precess at the same rate in a static magnetic field. Spin dressing has been studied in the context of the neutron [3], helium-3 [4], and other systems [5]. Critical dressing, however, has not previously been demonstrated. We will present results from recent experiments in which simultaneous dressing of two spin species is studied, and in which critical dressing is observed. [1] Phys Rep {\bf 237}, 1 (1994) [2] J Phys (France) {\bf 30}, 153 (1969) [3] Phys Rev Lett {\bf 58}, 2047 (1987) [4] Phys Rev A {\bf 85}, 3 (2012) [5] Nature 471, {\bf 83} (2011); Nature {\bf 476}, 185 (2011) [Preview Abstract] |
Saturday, October 15, 2016 12:30PM - 12:42PM |
JG.00009: ABSTRACT WITHDRAWN |
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