Microcomputer program for analysis of positron annihilation lifetime spectra

A user friendly program (LT) for analysis of the lifetime spectra has been designed for personal computers. The program is compared with other existing programs such as POSITRONFIT, CONTIN and MELT. LT enables one to analyse both discrete and continuous spectra as well as mixed-partially linear and partially continuous spectra. The searched parameters are found by using a fully automatic procedure and/or by a nonlinear optimising procedure, starting from a set of chosen parameters. The program is tested for series of simulated data as well as some chosen experimental ones, especially for the two polymers PTFE and hard polyethylene. The analysis of these polymer spectra is carried out on the basis of the log-normal distribution model and a new model of the lifetime spectrum developed by Dauwe et al., recently adapted to LT.