Development and study of magnetic shields for neutrino detector photomultiplier tubes under Neutrino-4M experiment on PIK and SM-3 reactors

A shielding system on the basis of MAP-1K rolled magnetic material was simulated and made, and is designed to protect photomultiplier tubes integrated in new neutrino detectors under NEUTRINE-4M experiment against Earth's magnetic field. Shielding coefficient was calculated for an individual cylindrical shield and assembly of 25 shields with the shielding structure axis directed along or across Earth's horizontal magnetic field. The obtained experimental data was compared with computer simulated data. Features of interaction between the shields in the system were examined. It was demonstrated that there is virtually no Earth's magnetic field effect on the detector performance when the detector is moved and rotated in the experiment with a new neutrino detector furnished with magnetic shields.