Simultaneous positron lifetime and momentum measurements of the vacancy formation enthalpy in aluminium

Positron annihilation spectroscopy (PAS) has enjoyed rapid growth as a new technique for the determination of the vacancy formation enthalpy, Esub(v)sup(F) in metals. The present experiments were undertaken to compare the two fundamental types of PAS techniques, momentum-distribution and lifetime measurements, as they are applied to the determination of Esub(v)sup(F). Although previous positron annihilation measurements of Esub(v)sup(F) have been carried out on aluminum, in the present work Doppler-broadening and lifetime experiments were performed simultaneously on Al over the temperature range 20-4350C in order to determine if the momentum and lifetime techniques, each with their own inherent experimental and analysis problems, could in fact result in the same quantitative determination of the vacancy formation enthalpy. (Auth.)