ACME III: Progress Towards an Improved Electron EDM Measurement

ORAL

Abstract

The electron electric dipole moment is a sensitive probe of CP-violating physics beyond the Standard Model. Using a cryogenic beam of thorium monoxide molecules, the ACME collaboration seeks to measure the electron electric dipole moment (EDM) at the 10-31 e cm level, an order of magnitude improved sensitivity over the current best limit [1] and the previous limit set by ACME II [2]. We achieve this improved sensitivity via a new experimental apparatus that provides a 5x longer spin precession time [3], an electrostatic lens [4], photodetectors with higher quantum efficiency [5], improved fluorescence collection optics, and in-situ target changes [6]. We present on the progress towards identifying and suppressing all systematic errors below our target sensitivity, and provide an update on the final stages of the ACME III experiment.

[1] JILA Gen. II result: Science 381, 46-50(2023).

[2] ACME Collaboration. Nature 562, 355–360 (2018). 

[3] D. G. Ang et al, Phys. Rev. A 106, 022808 (2022).

[4] X. Wu et al, New J. Phys. 24 073043 (2022)

[5] A. Hiramoto et al, Nucl. Instrum. Methods Phys. Res., Sect. A, 1045 (2023)

[6] Z. Han et al, arXiv:2505.11647 (2025)

*This work was supported by the National Science Foundation, the Gordon and Betty Moore Foundation, the Alfred P. Sloan Foundation, JSPS Kakenhi, and Okayama University RECTOR program.

–

Presenters

  • Collin R Diver

    • Northwestern University

Authors

  • Collin R Diver

    • Northwestern University

  • David DeMille

    • University of Chicago
    • Johns Hopkins University
    • Johns Hopkins University, Argonne National Laboratory, University of Chicago

  • John M Doyle

    • Harvard University

  • Xing Fan

    • Harvard University

  • Gerald Gabrielse

    • Northwestern University

  • Zhen Han

    • University of Chicago

  • Ayami Hiramoto

    • Northwestern University, Okayama University
    • Northwestern University

  • Peiran Hu

    • University of Chicago

  • Nicholas R Hutzler

    • Caltech
    • California Institute of Technology

  • Zack Lasner

    • Harvard University

  • Takahiko Masuda

    • Okayama Univ

  • Cristian D Panda

    • University of Arizona
    • The University of Arizona

  • Satoshi Uetake

    • Okayama University
    • Okayma Univ

  • Maya M Watts

    • Northwestern University

  • Xing Wu

    • Michigan State University
    • National Superconducting Cyclotron Laboratory, MSU

  • Koji Yoshimura

    • Okayama University
    • Okayama Univ