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

Thesis/Dissertation · Tue Jan 01 04:00:00 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
• Country of Publication: United States
• Language: English

Related Subjects

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