Darmstadt 2016 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 30: Instrumentation VIII

HK 30.2: Vortrag

Dienstag, 15. März 2016, 17:00–17:15, S1/01 A3

Precise measurements and shimming of magnetic field gradients in the low field regime — •Fabian Allmendinger¹, Olivier Grasdijk³, Werner Heil², Klaus Jungmann³, Sergei Karpuk², Hans-Joachim Krause⁴, Andreas Offenhäuser⁴, Maricel Repetto², Ulrich Schmidt¹, Yuri Sobolev², Lorenz Willmann³, and Stefan Zimmer² for the MIXed collaboration — ¹Physikalisches Institut , Universität Heidelberg — ²Institut für Physik, Universität Mainz — ³University of Groningen — ⁴Peter Grünberg Institut, Forschungszentrum Jülich

For many experiments at the precision frontier of fundamental physics, the accurate measurement and knowledge of magnetic field gradients in particular in the low field regime (<µT) is a necessity: On the one hand, in the search for an Electric Dipole Moment (EDM) of free neutrons or atoms, field gradients contribute to geometric-phase-induced false EDM signals for particles in traps. On the other hand, clock comparison experiments like the ³He/¹²⁹Xe spin clock experiment suffer from gradients, since the coherent T₂^*-time of free spin precession, and thus the measurement sensitivity, scales ∝ |∇B^→|⁻². Here we report on a new and very effective method, to shim and to measure tiny magnetic field gradients in the range of pT/cm by using effective T₂^*-measurement sequences in varying the currents of trim coils of known geometry.