https://doi.org/10.1140/epjc/s10052-025-14295-7
Regular Article - Experimental Physics
A compact frozen-spin trap for the search for the electric dipole moment of the muon
1
ETH Zürich, 8093, Zurich, Switzerland
2
PSI Center for Scientific Computing, Theory, and Data, 5232, Villigen PSI, Switzerland
3
ASTeC, STFC Daresbury Laboratory, Sci-Tech Daresbury, WA4 4AD, Warrington, UK
4
Cockcroft Institute, Sci-Tech Daresbury, WA4 4AD, Warrington, UK
5
Lancaster University, Lancaster, UK
6
INFN Pisa, Pisa, Italy
7
Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
8
School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
9
PRISMA+ Cluster of Excellence and Institute of Nuclear Physics, Johannes Gutenberg University Mainz, Mainz, Germany
10
Physics Department Pisa, Pisa, Italy
11
PSI Center for Accelerator Science and Engineering, 5232, Villigen PSI, Switzerland
12
Physik-Institut, Universität Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
13
PSI Center for Neutron and Muon Sciences, 5232, Villigen PSI, Switzerland
14
Sapienza Università di Roma, Dip. di Fisica, P.le A. Moro 2, 00185, Rome, Italy
15
INFN, Sez. di Roma, P. le A. Moro 2, 00185, Rome, Italy
16
University of Liverpool, Liverpool, UK
17
University College London, London, UK
18
CERN, Beams Department, 1211, Geneva, Switzerland
19
Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
20
Department of Physics and Astronomy, University of Manchester, Manchester, UK
21
School of Natural Sciences, Technical University of Munich, Garching, Germany
22
Instituto de Ingeniería, Universidad Nacional Autónoma de México, Mexico, Mexico
23
Swiss Plasma Center, École Polytechnique Fédérale de Lausanne, Villigen, Switzerland
a
philipp.schmidt-wellenburg@psi.ch
Received:
4
February
2025
Accepted:
7
May
2025
Published online:
6
June
2025
Electric dipole moments (EDM) of fundamental particles inherently violate time-reversal (T) and the combined charge-conjugation and parity symmetry (CP). We aim to measure the EDM of the muon using the frozen-spin technique within a compact storage trap. This method exploits the high effective electric field, 
, experienced in the rest frame of the muon with a momentum of about 
when it passes through a solenoidal magnetic field of 
. In this paper, we outline the fundamental considerations for a muon EDM search and present a conceptual design for a demonstration experiment to be conducted at secondary muon beamlines of the Paul Scherrer Institute in Switzerland. In Phase I, with an anticipated data acquisition period of 200 days, the expected sensitivity to a muon EDM is 
. In a subsequent phase, Phase II, we propose to improve the sensitivity to 
using a dedicated instrument installed on a different beamline that produces muons of momentum 125 
.
© The Author(s) 2025
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Funded by SCOAP3.
