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HK: Fachverband Physik der Hadronen und Kerne

HK 9: Fundamentale Symmetrien

HK 9.2: Gruppenbericht

Montag, 17. März 2014, 17:00–17:30, HZ 3

New limit on Lorentz and CPT violating neutron spin interactions using a free precession ³He-¹²⁹Xe co-magnetometer — •Fabian Allmendinger¹, Ulrich Schmidt¹, Werner Heil², Sergei Karpuk², Anja Scharth², Yuri Sobolev², Kathlynne Tullney², and Stefan Zimmer² for the He-Xe-comagnetometer collaboration — ¹Physikalisches Institut, Ruprecht-Karls-Universität, 69120 Heidelberg, Germany — ²Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany

We performed a search for a CPT and Lorentz invariance violating coupling of the ³He and ¹²⁹Xe nuclear spins (each largely determined by a valence neutron) to background tensor fields which permeate the universe. Our experimental approach is to measure the free precession of nuclear spin polarized ³He and ¹²⁹Xe atoms in a homogeneous magnetic guiding field of about 400 nT using LT_C SQUIDs as low-noise magnetic flux detectors. As the laboratory reference frame rotates with respect to distant stars, we look for a sidereal modulation of the Larmor frequencies of the co-located spin samples. As a result we obtain an upper limit on the equatorial component of the background field interacting with the spin of the bound neutron b_⊥ⁿ < 6.7 · 10⁻³⁴ GeV (68%  C.L.). Our result improves our previous limit (data measured in 2009) by a factor of 30 and the world’s best limit by a factor of 5. In the talk we will give an overview of the principle of measurement and current results.