Vacuum properties of high quality value tuning fork in high magnetic field up to 8 Tesla and at mK temperatures

Tuning forks are very popular experimental tools widely applied in low and ultra low temperature physics as mechanical resonators and cantilevers in the study of quantum liquids, STM and AFM techniques, etc. As an added benefit, these forks being cooled, have very high Q-value, typically $10^6$ and their properties seems to be magnetic field independent. We present preliminary vacuum measurements of a commercial tuning fork oscillating at frequency 32~kHz conducted in magnetic fields up to 8~T and at temperature $\sim 10$~mK. We found an additional weak damping of the tuning fork motion depending on magnetic field magnitude and we discuss physical nature of the observed phenomena.