The magnetic field can be generated with a superconducting magnet filled with liquid helium. The more traditional iron magnets are not preferred due to their large mass and limited geometrical acceptance for the produced particles. The target polarization during the experiment is determined with the nuclear magnetic resonance method. The integrated enhanced NMR-signals are compared to the signals taken in superfluid helium-4 bath at well known calibration temperatures around 1 K, where the spin magnetization follows the Curie law and the nuclear polarization can be calculated from the temperature by using the Brillouin function. During the polarization build up a microwave generator is used to pump the paramagnetic centers in the target material close to the electron spin resonance frequency (about 70 GHz in 2.5 T field).