  The research on the longitudinal ultrasound absorption in an intermediate
state of the high pure Gallium single crystal at the frequency of 50-190MHz at
the temperatures of 0,37-0,75 K, using the impulse method, is conducted. The
new effects in the absorption of ultrasound in an intermediate state of the
high pure type I superconductor are discovered. The big oscillations in the
dependence of the ultrasound absorption on the magnetic field in an
intermediate state of the high pure Gallium single crystal are experimentally
observed at the magnitudes of magnetic field below the critical magnetic field.
The maximum of the monotonic absorption of longitudinal ultrasound in an
intermediate state of the high pure type I superconductor is also obtained. The
possible original theoretical mechanisms to explain the nature of big
oscillations in the dependence of the ultrasound absorption on the magnetic
field in an intermediate state of the high pure type I superconductor are
proposed.
