Resonant ultrasound spectroscopy of free vibrating oscillators for massive particles detection

The half-inch diameter quartz oscillators are set for free vibrations. The crystal admittance (Y) versus frequency of ultrasound (F) is measured near fundamental harmonic of 9-10 MHz. The quartz crystallographic axes X, Y, interplain and rotated are oriented in space toward the sky locations of the Sun, center of the Milky Way galaxy or another star. It is demonstrated that Y(F) spectra are sensitive to an alignment of the crystallographic axes with space direction toward the stars. The two general results include: (1) changing Y(F) from a few to tens of percents under aligning crystallographic axes toward the stars and (2) occurring periodic minima in Y(F)-dependencies taken during some seconds with a tracking generator synchronized with a spectrum analyzer. The deepest minima in Y(F) appear when the azimuths of crystal axes coincide with those of the stars. These changes may be explained by electrically neutral massive particles (mp) emitted from a star and interacting with the crystals. The mass of a single mp-particle is estimated around ∼5 × 10−21 kg. RUS measurements correlate with the data from a crystal pendulum having a quartz bob and starts swinging when mp-particle hits it. RUS of free vibrating oscillators is perspective for detecting stellar massive particles.