Measurement of the Permanent Electric Dipole Moment of the Neutron

C. Abel, S. Afach, N. J. Ayres, C. A. Baker, G. Ban, G. Bison, K. Bodek, V. Bondar, M. Burghoff, E. Chanel, Z. Chowdhuri, P. J. Chiu, B. Clement, C. B. Crawford, M. Daum, S. Emmenegger, L. Ferraris-Bouchez, M. Fertl, P. Flaux, B. FrankeA. Fratangelo, P. Geltenbort, K. Green, W. C. Griffith, M. Van Der Grinten, Z. D. Grujić, P. G. Harris, L. Hayen, W. Heil, R. Henneck, V. Hélaine, N. Hild, Z. Hodge, M. Horras, P. Iaydjiev, S. N. Ivanov, M. Kasprzak, Y. Kermaidic, K. Kirch, A. Knecht, P. Knowles, H. C. Koch, P. A. Koss, S. Komposch, A. Kozela, A. Kraft, J. Krempel, M. Kuźniak, B. Lauss, T. Lefort, Y. Lemière, A. Leredde, P. Mohanmurthy, A. Mtchedlishvili, M. Musgrave, O. Naviliat-Cuncic, D. Pais, F. M. Piegsa, E. Pierre, G. Pignol, C. Plonka-Spehr, P. N. Prashanth, G. Quéméner, M. Rawlik, D. Rebreyend, I. Rienäcker, D. Ries, S. Roccia, G. Rogel, D. Rozpedzik, A. Schnabel, P. Schmidt-Wellenburg, N. Severijns, D. Shiers, R. Tavakoli Dinani, J. A. Thorne, R. Virot, J. Voigt, A. Weis, E. Wursten, G. Wyszynski, J. Zejma, J. Zenner, G. Zsigmond

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221 Citations (SciVal)


We present the result of an experiment to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute using Ramsey's method of separated oscillating magnetic fields with ultracold neutrons. Our measurement stands in the long history of EDM experiments probing physics violating time-reversal invariance. The salient features of this experiment were the use of a Hg199 comagnetometer and an array of optically pumped cesium vapor magnetometers to cancel and correct for magnetic-field changes. The statistical analysis was performed on blinded datasets by two separate groups, while the estimation of systematic effects profited from an unprecedented knowledge of the magnetic field. The measured value of the neutron EDM is dn=(0.0±1.1stat±0.2sys)×10-26

Original languageEnglish
Article number081803
JournalPhysical Review Letters
Issue number8
StatePublished - Feb 28 2020

Bibliographical note

Funding Information:
We are profoundly grateful for the fundamental contributions to the field, in general, and to this project, in particular, of J. M. Pendlebury and to K. F. Smith and others also involved with the original development of the nEDM spectrometer with Hg comagnetometer. We acknowledge the excellent support provided by the PSI technical groups and by various services of the collaborating universities and research laboratories. In particular, we acknowledge with gratitude the long-term outstanding technical support by F. Burri and M. Meier. We thank the UCN source operation group BSQ for their support. We acknowledge financial support from the Swiss National Science Foundation through Projects No. 117696, No. 137664, No. 144473, No. 157079, No. 172626, No. 126562, No. 169596 (all PSI), No. 181996 (Bern), No. 162574 (ETH), No. 172639 (ETH), and No. 140421 (Fribourg). University of Bern acknowledges the support via the European Research Council under the ERC Grant Agreement No. 715031-BEAM-EDM. Contributions of the Sussex group have been made possible via STFC Grants No. ST/M003426/1, No. ST/N504452/1, and No. ST/N000307/1. LPC Caen and LPSC Grenoble acknowledge the support of the French Agence Nationale de la Recherche (ANR) under Reference No. ANR-09-BLAN-0046 and the ERC Project No. 716651-NEDM. The Polish collaborators acknowledge support from the National Science Center, Poland, under Grants No. 2015/18/M/ST2/00056, No. 2016/23/D/ST2/00715, and No. 2018/30/M/ST2/00319. P. M. acknowledges State Secretariat for Education, Research and Innovation (SERI) Grant No. SERI-FCS 2015.0594. This work was also partly supported by the Fund for Scientific Research Flanders (FWO) and Project No. GOA/2010/10 of the KU Leuven. We acknowledge the support from the DFG (DE) specifically Projects No. BI 1424/2-1 and No. BI 1424/3-1. In addition, we are grateful for access granted to the computing grid PL-Grid infrastructure.

Publisher Copyright:
© 2020 authors. Published by the American Physical Society.

ASJC Scopus subject areas

  • Physics and Astronomy (all)


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