Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session 1WDA: Fundamental Physics at Low Energy I |
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Chair: Yasuhiro Sakemi, CNS, University of Tokyo Room: Hilton Kohala 3 |
Tuesday, October 23, 2018 9:00AM - 9:30AM |
1WDA.00001: Nuclear Structure and Atomic Electric Dipole Moments Invited Speaker: Jonathan H Engel To connect values of or limits on atomic EDMs in diamagnetic atoms, one must know the "Schiff moment" of the corresponding nucleus. At present these moments are known but not with much precision. Here I review the ways in which Schiff moments are calculated, discuss nuclear-structure information that is needed to improve their precision, and look at the theory and experiment needed to obtain that information. |
Tuesday, October 23, 2018 9:30AM - 10:00AM |
1WDA.00002: The Electric Dipole Moment of Radium Invited Speaker: Matthew R Dietrich The apparent excess of matter over anti-matter throughout the universe is one of the most pressing challenges in all of physics. This is because nature appears to respect the symmetry known as CP (charge conjugation-parity) almost perfectly, which implies matter and anti-matter should have been produced with precisely the same abundance during the Big Bang. Thus, new undiscovered sources of CP-violation are needed to explain the baryon asymmetry of the universe, and these sources feature prominantly in new theories that extend the standard model of particle physics, such as supersymmetry. Electric dipole moments (EDMs) are signatures of time-reversal, parity, and charge parity (CP) violation, which make them a sensitive probe of such physics. Due to its large nuclear octupole deformation and high atomic mass, the radioactive Ra-225 isotope is a favorable EDM case; it is particularly sensitive to CP-violating interactions in the nuclear medium. To measure this rare isotope, we have developed an approach to measuring EDMs by using lasers to cool those atoms to 40 micro-Kelvins, and trapping them in a optical dipole trap. Using this method, we have found the EDM of radium to be less than 1.4e-23 e-cm (95% C.L). Recent improvements to the apparatus that will dramatically improve its sensitivity in the near term will be discussed. |
Tuesday, October 23, 2018 10:00AM - 10:30AM |
1WDA.00003: Co-existing Xe-129 and Xe-131 masers with active feedback scheme for Xe atomic EDM search Invited Speaker: Tomoya Sato A permanent electric dipole moment (EDM) of a particle will be induced due to the violation of time reversal invariance, or equivalently the CP-symmetry. A finite EDM would indicate the CP-violation due to new physics beyond the Standard Model (BSM), which is essential in explaining the observed matter excess in the Universe. Improvements in the upper limits on EDMs for diamagnetic atoms should be important in the study of BSM, especially in the hadron sector1. In order to improve the current experimental upper limit on Xe atomic EDM, 4.1$\times$10-27 ecm2, we are developing a nuclear spin maser with an active feedback scheme, which enables us to observe spin motion avoiding the decay of precession3. We are developing co-existing Xe-129 and Xe-131 spin masers4 in order to eliminate the systematic instability in the maser frequency due to the drifts in the magnetic field and in the effective field caused by the Fermi-contact interaction between Xe and polarized Rb. Our recent study suggested that the motion of the Rb spin, which is used to observe the Xe spin precession, is affected by the feedback field for masing. In order to eliminate systematic errors arising from this effect, we developed a time-separated feedback (TSFB) scheme. In this scheme, the observation and the feedback for masing are separated in time. In addition, several efforts are made to improve the signal-to-noise ratio of the measurement which determines the final frequency precision. In this presentation, recent developments and progress of the co-existing Xe-129 and Xe-131 masers with TSFB scheme will be reported. |
Tuesday, October 23, 2018 10:30AM - 11:00AM |
1WDA.00004: COFFEE BREAK
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