Project

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Passive magnetic shield for the new neutron electric dipole moment experiment n2EDM

Applicant Kirch Klaus
Number 139140
Funding scheme R'EQUIP
Research institution Labor für Teilchenphysik Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Particle Physics
Start/End 01.01.2013 - 31.12.2016
Approved amount 500'000.00
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Keywords (4)

neutron; EDM; Mu-metal; Shielding

Lay Summary (English)

Lead
Lay summary

Measurements of the neutron Electric Dipole Moment (nEDM) with sensitivities better than 10^-26 e.cm are considered to be of top priority by the particle physics community, since they may provide information on new sources of CP violation and thus give clues as to the presence of physics ‘Beyond the Standard Model’ (BSM). An improved nEDM measurement is timely and will complement results expected from other projects sensitive to BSM physics, e.g. concerning supersymmetry signatures, such as experiments at the Large Hadron Collider (CERN) or searches for forbidden lepton-flavour changing processes such as the MEG experiment at the Paul Scherrer Institut (PSI). A nEDM project is pursued by an international collaboration at PSI (nedm.web.psi.ch) in a staged approach using an existing apparatus and developing a next measurement system called n2EDM. The n2EDM project aims at unprecedented magnetic field control over a sensitive volume of more than 250 liters down to a level of a few 10 fT and an adequate suppression of external field fluctuations.

To fight against the external magnetic field distortions and fluctuations, the n2EDM experiment will use a passive multilayer (5-6) mu-metal shielding in combination with a surrounding active field compensation system. This R'Equip grant for the n2EDM project is a major contribution to the passive mu-metal shielding which will be purchased in 2012 together with contributions from the collaboration, especially from ETHZ and PSI, and set up and qualified at PSI.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Publications

Publication
Gravitational depolarization of ultracold neutrons: Comparison with data
Afach S., Ayres N. J., Baker C. A., Ban G., Bison G., Bodek K., Fertl M., Franke B., Geltenbort P., Green K., Griffith W. C., van der Grinten M., Grujic Z. D., Harris P. G., Heil W., Helaine V., Iaydjiev P., Ivanov S. N., Kasprzak M., Kermaidic Y., Kirch K., Koch H. -C., Komposch S., Kozela A., Krempel J. (2015), Gravitational depolarization of ultracold neutrons: Comparison with data, in PHYSICAL REVIEW D, 92(5), 000000.
Measurement of a false electric dipole moment signal from Hg-199 atoms exposed to an inhomogeneous magnetic field
Afach S., Baker C. A., Ban G., Bison G., Bodek K., Chowdhuri Z., Daum M., Fertl M., Franke B., Geltenbort P., Green K., van der Grinten M. G. D., Grujic Z., Harris P. G., Heil W., Helaine V., Henneck R., Horras M., Iaydjiev P., Ivanovf S. N., Kasprzak M., Kermaidic Y., Kirch K., Knowles P., Koch H. -C. (2015), Measurement of a false electric dipole moment signal from Hg-199 atoms exposed to an inhomogeneous magnetic field, in EUROPEAN PHYSICAL JOURNAL D, 69(10), 000000.
Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy
Afach S., Ayres N. J., Ban G., Bison G., Bodek K., Chowdhuri Z., Daum M., Fertl M., Franke B., Griffith W. C., Grujic Z. D., Harris P. G., Heil W., Helaine V., Kasprzak M., Kermaidic Y., Kirch K., Knowles P., Koch H. -C., Komposch S., Kozela A., Krempel J., Lauss B., Lefort T., Lemiere Y. (2015), Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy, in PHYSICAL REVIEW LETTERS, 115(16), 000000.
Revised experimental upper limit on the electric dipole moment of the neutron
Pendlebury J. M., Afach S., Ayres N. J., Baker C. A., Ban G., Bison G., Bodek K., Burghoff M., Geltenbort P., Green K., Griffith W. C., van der Grinten M., Grujic Z. D., Harris P. G., Helaine V., Iaydjiev P., Ivanov S. N., Kasprzak M., Kermaidic Y., Kirch K., Koch H. -C., Komposch S., Kozela A., Krempel J., Lauss B. (2015), Revised experimental upper limit on the electric dipole moment of the neutron, in PHYSICAL REVIEW D, 92(9), 000000.

Collaboration

Group / person Country
Types of collaboration
LPC, Laboratoire de Physique Corpusculaire - Caen France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
ETHZ, Eidgenössische Technische Hochschule - Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Paul Scherrer Institut Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
KUL, Katholieke Universiteit - Leuven Belgium (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
FRAP, Université de Fribourg - Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Jagellonian University - Cracow Poland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
LPSC, Laboratoire de Physique Subatomique et de Cosmologie - Grenoble France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
PTB Physikalisch Technische Bundesanstalt Berlin Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
GUM, Institut für Physik, Gutenberg Universität - Mainz Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
HNI, Henryk Niedwodniczanski Institute of Nuclear Physics PAN - Cracow Poland (Europe)
- Publication

Scientific events



Self-organised

Title Date Place

Associated projects

Number Title Start Funding scheme
188700 A new search for an electric dipole moment of the neutron with increased sensitivity and an improved UCN source. 01.09.2020 Project funding
162574 Measurement of the neutron electric dipole moment 01.11.2015 Project funding
138211 Measurement of the neutron electric dipole moment 01.11.2011 Project funding
137664 Pushing the high intensity frontier for ultracold neutrons 01.11.2011 Project funding
201473 n2EDM: The next measurement of the neutron electric dipole moment (II) 01.04.2021 FLARE
172626 Highly accurate vector gradiometers for a next-generation neutron EDM experiment 01.08.2017 Project funding
200441 Precision Physics with Muons and Ultracold Neutrons II 01.05.2021 Project funding
177008 Field Generation and Control System for the n2EDM spectrometer 01.12.2017 R'EQUIP
186179 n2EDM: The next measurement of the neutron electric dipole moment 01.04.2019 FLARE
149211 Measurement of the neutron electric dipole moment 01.11.2013 Project funding
172639 Precision Physics with Muons and Ultracold Neutrons 01.05.2017 Project funding
130480 Optical magnetometry for a new neutron EDM experiment 01.04.2010 Project funding
126562 Search for the neutron EDM at the high intensity ultracold neutron source at PSI with an upgraded high sensitivity spectrometer 01.10.2009 Project funding

Abstract

The search for electric dipole moments (EDM) of fundamental systems presents a very promising route for finding new physics beyond the Standard Model (SM) of particle physics. A permanent electric dipole moment violates parity and time reversal symmetries and, invoking the CPT theorem, also CP symmetry. New sources of CP violation are needed in order to understand the observed large baryon asymmetry of our universe (BAU) and most extensions of the SM provide new CP violating phases. Non-observations of finite EDM, of the neutron as well as of nuclei, e.g. with the 199Hg atom, and the electron, e.g. via the 205Tlatom, present the most stringent constraints on new physics models of CP violation. Many efforts world wide are underway to search for EDM in various systems like atoms, molecules, muons, light nuclei and neutrons (nEDM, d_n).The importance of nEDM searches has been recognized in various recent roadmaps, e.g., for Swiss Particle Physics initiated by the Swiss Institute for Particle Physics CHIPP and in the current NUPECC Nuclear Physics Long Range Plan initiated by the European Science Foundation. CERN Council has emphasized the importance of the precision measurements at low energies in its European Strategy for Particle Physics. Also outside of Europe, the nEDM priority is very high, as reflected e.g. in the US long range plan for nuclear physics and efforts in Canada and Japan.The ETH and PSI groups play a leading role in the nEDM effort at PSI, presently improving and running the existing experimental apparatus aiming at a factor 5 improvement over the present nEDM limit within 2 years. During the same period, we plan to finish the design and begin construction for the subsequent n2EDM phase. Our target sensitivity of d_n < 5 x 10^{-28} ecm (95% C.L.) represents a factor of 100 improvement over the present limit and requires high precision control of magneticfields on the sub ten femtotesla level. This is only possible within a magnetically highly shielded environment. Our approach to the magnetic shielding is based on the separation into a multi-layer outer mu-metal shielding, using a state-of-the-art shielded room in cubic form, which can be provided by industry with guaranteed shielding performance, and a cylindric innermost shielding layer supporting the required high magnetic field homogeneity (10^{-4} level) of a microtesla field created by an inner coil system.With the present proposal, we ask for support to acquire the multi-layer mu-metal shielding, the most expensive individual setup item for the n2EDM experiment at the Paul Scherrer Institute (PSI). This shield will constitute a facility providing a volume of more than 6 m^3 of unique magnetic environment. It will be devoted to n2EDM for the first years but can in the future also serve other fundamental physics experiments, e.g. an improved search for mirror neutrons as a dark matter candidate, or baryon number violating neutron to anti-neutron oscillations. It can also serve developments, e.g. of high precision magnetometry, useful for various physics to bio-medical applications. The cost of the commercial passive magnetic shield amounts to2.6MCHF. The Emil-Berthele-Fonds via ETH Zuerich has alreadygranted a contribution of 1.3MCHF. Therefore, we here apply forthe remaining 1.3MCHF. The Paul Scherrer Institut will balance aR'Equip contribution of the SNF and the PSI Laboratory for ParticlePhysics and the ETH start-up grant of the main applicant willaccount for a potentially remaining difference.
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