Design and construction of an apparatus for the experimental search for the electric dipole moment (EDM) of 129xe

• Applicants: Professor Dr. Werner Heil; Professor Dr. Ulrich Schmidt
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2012 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 218861983

We propose to measure the permanent electric dipole moment (EDM) of the isotope 129Xe, which would imply a breakdown of both parity P and time-reversal symmetry T and, through the CPT theorem, a breakdown in CP, the combined symmetries of charge conjugation C and parity P. Our goal is to improve the present experimental limit (dXe < 3x10-27 e cm) by about four orders of magnitude. Historically, the non-observation of EDMs of particles and atoms has ruled out more speculative models (beyond the Standard Model) than any other single experimental approach in particle physics. The most precise EDM limit was measured in the diamagnetic atom 199Hg (dHg < 3.1x10-29 e cm). To get more stringent limits, we propose a 3He/129Xe clock comparison experiment with the detection of free spin precession of gaseous, nuclear polarized 3He or 129Xe samples with a SQUID as magnetic flux detector. The precession of co-located 3He/129Xe nuclear spins can be used as ultra-sensitive probe for non-magnetic spin interactions of type Δν ~ dXeE, since the magnetic dipole interaction (Zeeman-term) drops out in the frequency difference Δν of their Larmor frequencies. Compared to spin masers, the detection of free spin precession with spin coherence times T > 1 day doesn’t have the systematic limitations of a feedback loop necessary to sustain coherent spin precession.

• DFG Programme: Research Grants
• Major Instrumentation: SQUID gradiometer ; active and passive shielding
• Instrumentation Group: 0140 Magnetfeld- und -flußmeßgeräte (außer Geomagnetik 040) ; 2770 Störschutzgeräte und -anlagen, Faraday-Käfige