The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to determine the mass of the electron antineutrino with a sensitivity of 0.2 eV/c² (90% C.L.) in a model-independent approach. The integral β-spectrum is measured in an energy region close to 18.6 keV with an electromagnetic spectrometer (MAC-E filter) at the heart of a 70 m long setup.
The energy resolution of the spectrometer is largely defined by the magnetic field in the analyzing plane. This important operational parameter can be optimized in order to reduce the spectrometer-related background while still providing an excellent energy resolution of 1-2 eV for signal electrons. A good understanding of external magnetic fields e.g. from magnetized materials is essential. We present recent experimental studies of the magnetic field and its stability using magnetometer arrays and dedicated calibration devices. The results are employed to optimize the experiment's sensitivity.
We present studies of the magnetic field at the KATRIN main spectrometer during neutrino-mass runs.