Acoustic Microscopy at Cryogenic Temperatures
Annual summary rept. 1 Jul 80-30 Jun 81
STANFORD UNIV CA EDWARD L GINZTON LAB OF PHYSICS
Pagination or Media Count:
This report summarizes our progress in a research program devoted to high resolution acoustic microscopy and cryogenic temperatures. During the past year we have studied the acoustic properties of two cryogenic fluids - liquid argon and liquid 4He below the temperature of 0.5 degrees K. In argon we have determined that nonlinear effects provide us with a dramatic increase in resolving power for focused acoustic beams. In liquid helium we have measured the attenuation versus temperature of sound at 1 GHz where the wavelength is less than 2500 A. The predicted behavior below 0.5 degrees K where the attenuation varies as the fourth power of temperature is confirmed for the first time at these small wavelengths. It gives us further confidence in our program to realize an instrument that will permit us to examine our specimens with an acoustic probe that is less than 1000 A in diameter.
- Test Facilities, Equipment and Methods