Measuring smallest magnetic field gradients using hyperpolarized 129Xenon

Explaining the observed baryon asymmetry in our universe is one of the unsolved problems in physics. Solving it with the well-known Standard Model is not possible, due to missing sources of CP violation. Therefore, a more general model is needed in which the Standard Model is embedded. Using the 3 He/ 129 Xe comagnetometer, it is possible to measure the permanent electric dipole moment (EDM) of 129 Xe atoms which may provide an experimentally accessible signal for additional sources of CP violation. To be able to perform such measurements, homogeneous magnetic fields with gradients at the level of pT/cm are required. Therefore, an MSR (magnetically shielded room) was constructed in the year 2021 at the Physikalisches Institut in Heidelberg. In the scope of this thesis, this new MSR was characterized and a novel degaussing routine could be motivated and tested yielding to a measured residual magnetic field of (1.2 ± 0.2) nT at the center. Furthermore, an existing setup producing HP (hyperpolarized) 129 Xe was commissioned and optimized. A dedicated calibration of the NMR signal of HP xenon revealed an absolute polarization of up to (37 ± 3) % in flow mode and (18.8 ± 0.5) % after accumulation which could be reproducibly achieved. HP xenon gas could be successfully transferred into the MSR in order to perform first systematic tests. Storage times of up to T1 = (8521 ± 254) s and a coherent precession time of T2∗ = (4137 ± 17) s could be reached. These characteristics allowed for precise measurements of magnetic field gradients within the MSR with a sensitivity below 1 pT/cm. Thus, this work laid an important foundation for future 129 Xe-EDM measurements.