Deconvoluted Doppler broadened positron annihilation spectroscopy: characterization of defects in aluminium

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5499061

Schaffer, J P

Positron Annihilation Spectroscopy (PAS) has become a useful tool for the nondestructive investigation of the defect structure of materials. Of the existing PAS measurement techniques Doppler broadening appears to offer several practical advantages. In an attempt to overcome the difficulties associated with the use of Doppler broadened PAS the Fast Fourier Transform/Power Spectrum (FFT/PS) deconvolution algorithm has been developed in this work. This algorithm is computationally efficient, noniterative, and requires minimal a priori information. The utility of the FFT/PS deconvolution algorithm is demonstrated for high purity aluminum samples containing known concentrations of vacancies or prismatic dislocation loops. It is shown that the FFT/PS procedure is capable of automatically correcting for accidental and/or intentional changes in the instrument resolution function. In addition, based on the limited data analyzed in this work, it appears that both the sensitivity and the accuracy of the energy distribution lineshape parameters are improved by deconvolution. Finally, it is demonstrated that if the filtering error introduced by the FFT/PS procedure is controlled, then it is possible to distinguish between samples containing predominately vacancy type defects and those with prismatic dislocation loops as the dominant defect type.

• Research Organization: Duke Univ., Durham, NC (USA)
• OSTI ID: 5499061
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
36 MATERIALS SCIENCE
ALUMINIUM
CRYSTAL DEFECTS
SPECTROSCOPY
SPECTRA UNFOLDING
ALGORITHMS
ANNIHILATION
DOPPLER BROADENING
POSITRONS
RESOLUTION
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
CRYSTAL STRUCTURE
DATA PROCESSING
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
INTERACTIONS
LEPTONS
LINE BROADENING
MATHEMATICAL LOGIC
METALS
PROCESSING
440300* - Miscellaneous Instruments- (-1989)
360102 - Metals & Alloys- Structure & Phase Studies