A two-detector spectrometer for measurements of Doppler broadened positron annihilation spectra

A two-detector spectrometer for measurements of Doppler broadened positron annihilation spectra has been constructed and tested. The energy difference of the annihilation quanta is measured in the analogue, not in the digital manner. The peak to background ratio in the measured spectra is of the order of 106, the FWHM representing the energy resolution, equals to 1.1 keV, thus enabling the very subtle physical effects to be revealed. nformation on electronic structure of the investigated 3-d metals (Ti, V, Cr, Fe, Ni, Cu and Zn) has been determined using this spectrometer. It has been shown that the apparatus permits to detect the impurity-vacancy pairs in dilute nickel alloys containing 1% of Zr admixture.