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The neutron electric dipole moment experiment at the Spallation Neutron Source...

Publication Type
Conference Paper
Journal Name
EPJ Web of Conferences
Publication Date
Page Number
Conference Name
International Workshop on Particle Physics at Neutron Sources (PPNS 2018)
Conference Location
Grenoble, France
Conference Sponsor
Institut Laue-Langevin (ILL), the Laboratoire de Physique Subatomique et de Cosmologie (LPSC), the ENIGMASS project, and SwissNeutronics
Conference Date

Novel experimental techniques are required to make the next big leap in neutron electric dipole moment experimental sensitivity, both in terms of statistics and systematic error control. The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) will implement the scheme of Golub & Lamoreaux [Phys. Rep., 237, 1 (1994)]. The unique properties of combining polarized ultracold neutrons, polarized 3He, and superfluid 4He will be exploited to provide a sensitivity to ∼ 10−28 e · cm. Our cryogenic apparatus will deploy two small (3 L) measurement cells with a high density of ultracold neutrons produced and spin analyzed in situ. The electric field strength, precession time, magnetic shielding, and detected UCN number will all be enhanced compared to previous room temperature Ramsey measurements. Our 3He co-magnetometer offers unique control of systematic effects, in particular the Bloch-Siegert induced false EDM. Furthermore, there will be two distinct measurement modes: free precession and dressed spin. This will provide an important self-check of our results. Following five years of “critical component demonstration,” our collaboration transitioned to a “large scale integration” phase in 2018. An overview of our measurement techniques, experimental design, and brief updates are described in these proceedings.