Accession Number : AD0721102

Title :   Femtovolt Measurements of the Superconducting Transition in Tin Whisker Crystals.

Descriptive Note : Technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS

Personal Author(s) : Newbower,Ronald S.

Report Date : JAN 1971

Pagination or Media Count : 224

Abstract : The onset of the resistive transition of one-dimensional superconductors has been studied with as much as 10 to the -15th power volt sensitivity, at currents as low as 0.000 000 1 ampere. The bahavior in this region is determined by thermodynamic fluctuations of the order parameter. Measurements at 0.000 0002A on pure tin, single-crystal whiskers approximately one-half micron in diameter, agree over five decades of resistance change with the explicit predictions of the McCumber-Halperin modification of the Langer-Ambegaokar theory. Extensive development of the technology of Josephson-junction superconducting voltmeters was undertaken in the course of this experiment. A detailed analysis of the practical and fundamental bandwidth and sensitivity limitations of these techniques is given. (Author)

Descriptors :   (*SUPERCONDUCTORS, TRANSITION TEMPERATURE), (*TIN, SUPERCONDUCTIVITY), (*ELECTRICAL RESISTANCE, MEASUREMENT), WHISKERS(CRYSTALS), SINGLE CRYSTALS, TUNNELING(ELECTRONICS), MAGNETOMETERS, GALVANOMETERS, VOLTMETERS, CRYOGENICS

Subject Categories : Test Facilities, Equipment and Methods
      Electricity and Magnetism
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE