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The search for the neutron electric dipole moment at PSI

by Guillaume Pignol, Philipp Schmidt-Wellenburg

This is not the current version.

Submission summary

As Contributors: Philipp Schmidt-Wellenburg
Preprint link: scipost_202102_00004v1
Date submitted: 2021-02-02 07:52
Submitted by: Schmidt-Wellenburg, Philipp
Submitted to: SciPost Physics Proceedings
Proceedings issue: PSI Particle Physics
Academic field: Physics
  • High-Energy Physics - Experiment
Approach: Experimental


The existence of a nonzero permanent electric dipole moment (EDM) of the neutron would reveal a new source of CP violation and shed light on the origin of the matter--antimatter asymmetry of the Universe. The sensitivity of current experiments using stored ultracold neutrons (UCN) probes new physics beyond the TeV scale. Using the UCN source at the Paul Scherrer Institut, the nEDM collaboration has performed the most sensitive measurement of the neutron EDM to date, still compatible with zero ($|d_n|<1.8\times 10^{-26} \, e {\rm cm}$). A new experiment designed to improve the sensitivity by an order of magnitude, n2EDM, is currently in construction.

Current status:
Has been resubmitted

Submission & Refereeing History

Resubmission 2103.01898v1 on 3 March 2021

Reports on this Submission

Anonymous Report 2 on 2021-2-22 (Invited Report)


This is a nice, concise report on the effort at PSI to search for the
neutron electric dipole moment. It should be accepted for publication.

I have the following minor comments, which the authors may wish to address.

1) line 9: The confidence level corresponding to the quoted limit should
be indicated.

2) line 49: I would add "In many nEDM search experiments", as not all
nEDM experiments use Ramsey's method.

3) lines 60-61: alpha is the product of the neutron polarization and
the analyzing power of the spin analyzer

4) line 69: this paragraph is about the PSI effort, where as the
previous paragraph is a general remark. To make this clear, I would
add "at PSI" after "In the single chamber apparatus", so that the
beginning of line 69 would read "In the single chamber apparatus at

5) Figures 27.3 and 27.4: latex error in reference citation in the figure

6) line 289: fix typesetting of Gilles Quemener's name. ("e" with accent aigu is
not properly typeset)

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Report 1 by Adrian Signer on 2021-2-9 (Invited Report)


We (the editors Cy Hoffman, Klaus Kirch, Adrian Signer) had the
opportunity to review an earlier draft of the article and were in
communication with the authors before the submission. All our comments
and suggestions have been taken into account. Hence, we think the
paper can now be published in the current form.

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