New effects in absorption of ultrasound in intermediate state of high   pure type I superconductor
  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. 
Anatoly G. Shepelev, Oleg P. Ledenyov and Genady D. Filimonov
cond-mat.supr-con cond-mat.mtrl-sci physics.ins-det