First Measurement of the Permanent Electric Dipole Moment of Radium-225

ORAL

Abstract

Electric dipole moments (EDMs) are signatures of time-reversal ($T$), parity ($P$),\& charge-parity ($CP$) violation. $CP$-violation beyond the Standard Model is generally believed to be required to explain the observed prevalence of matter over antimatter in the universe. Radium-225 ($\tau_{1/2} = 14.7$ d, $I = 1/2$) is mostly sensitive to $T$- and $P$-violating interactions originating within the nucleus. The best limits on these types of exotic interactions are derived from the atomic EDM limit for Mercury-199. Because of its unusual nuclear structure (octupole deformation), Ra-225 is expected to have a physics sensitivity that is a few hundred to a few thousand times higher than Hg-199. Laser cooling \& trapping techniques are performed to collect \& transport the cold Ra atoms into the measurement region. An EDM measurement is then performed by searching for a linear electric field dependent shift in the nuclear spin precession frequency of Ra-225. We will report on the first measurement of the atomic EDM of Ra-225 as well as plans for future improvements.

Authors

  • Jaideep Singh

    Michigan State University, NSCL/MSU, Michigan State University and NSCL

  • K.G. Bailey

    Argonne National Lab

  • M.N. Bishof

    Argonne National Lab

  • M.R. Dietrich

    Northwestern University, Argonne National Lab

  • J.P. Greene

    Argonne National Laboratory, Argonne National Lab

  • R.J. Holt

    Argonne National Lab

  • M.R. Kalita

    University of Kentucky

  • W. Korsch

    University of Kentucky

  • N.D. Lemke

    Argonne National Lab

  • Z.-T. Lu

    Argonne National Laboratory, Argonne National Lab, University of Chicago

  • P. Mueller

    Argonne National Lab

  • T.P. O'Connor

    Argonne National Lab

  • R.H. Parker

    University of Chicago, Argonne National Lab