Patent · US Expired

Method of measuring pore diameters by positronium decay

US4897549A · kind A · utility

9Cited by

7References

4Claims

0Family size

Inventors

Tadeusz W. Zerda · Fort Worth, US
Bruce E. Miller · Waltham, US
C. A. Quarles · Fort Worth, US

Key dates

Filing date	Dec 19, 1988
Grant date	Jan 30, 1990
Priority date	—
Expiry date	Dec 19, 2008

Classification

Technology area (CPC G)Physics
CPC primaryG01N2223/649
WIPO fieldMeasurement
WIPO sectorInstruments

Abstract

A method is shown for measuring naturally occurring pores in a specimen material. A positron is emitted from a radioactive source and enters a material to pick up an electron to form positronium. The positronium decays very rapidly into two gamma rays. The lifetime of the positronium depends on the size of the pore it is trapped within. The larger the pore, the longer the positronium will last. By measuring the decay rate of positrons over an extended time scale in the range from 30 to 500 nsec., a near relation can be developed between positronium lifetime and pore diameter.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.