Technique for position lifetime spectra unfolding

Technique for unfolding the spectra of positron annihilation in metals enabling to improve sufficiently the confidence of positron lifetime determination is suggested. It is shown that the problem of lifitime determination is limited by the accuracy of determination of analyzer channel width Δ with following determination of the resolution parameter σ at which the best convergence for the program of computerized spectrum unfolding is achieved. Therefore the following procedure of spectrum unfolding is recommended. At least two spectra of investigated samples characterized by different proton lifetime are recorded during equipment operation without switching-off. Two values of the channel multiplying factor differing by 2-3% are assigned for computerized processing σ values presenting the best convergence at each of chosen values of channel multiplying factor are determined for all spectra obtained during one period of operation. The common point of convergence lines, that is the real Δ0 and σ0 values are determined graphically or analytically. All obtained spectra are unfolded using these values. Results reproducibility with application of the described technique equals +-1ns