Introduction
PALSfit3 is a computer program for the analysis of positron lifetime spectra (measured by positron annihilation lifetime spectroscopy, PALS). PALSfit3 is based on the previous PATFIT and PALSfit programs, which have been used extensively by the positron annihilation community. PALSfit3 is the most recent update of PALSfit with improved graphics output.

PALSfit3 is composed of two modules for fitting of positron lifetime spectra, PositronFit and ResolutionFit. In both fitting modules a model function will be fitted to a measured lifetime spectrum. This model function consists of a function representing the physics of the positron decay convoluted with the experimental time resolution function, plus a constant background. The 'physics function' consists of a sum of decaying exponentials each of which may be broadened by convolution with a log-normal distribution. The time resolution function is described by a sum of Gaussians which may be displaced with respect to each other. Various types of constraints may be imposed on the fitting parameters.

In the PositronFit module, the fitting parameters to be extracted from a measured spectrum are for each lifetime component its mean lifetime and its broadening as well as its intensity. A correction for positrons annihilating outside the sample ("source correction") can be made as part of the analysis.

In the ResolutionFit module, parameters determining the shape of the time resolution function can be fitted. The extracted resolution function may then be used in PositronFit.

The main results will be displayed in a text window. In addition graphics displays are provided to ease the selection of some of the input parameters and to display results of spectrum analyses.

PALSfit3 is verified on Windows 7, 8, 10. and 11

 
Documentation

The user interface of PALSfit3 is to a large extent selfexplanatory.
The official PALSfit3 report is found here:	PALSfit3_report
Previous reports related to PALSfit:	List of older reports
References related to PALSfit:	List of publications related to PALSfit (by the PALSfit-team)
Description of spectrum files	PALSfit spectrum files
List of types of files	File types used by PALSfit

 
How to acquire PALSfit3
The full version of PALSfit3, including test data, can be installed here (PALSfit3 version 3.251).

To be able to run the PALSfit3 program, a license key is required.

If you have previously obtained a license key, you may use it for PALSfit3.

To obtain a license key for the first time, please print the standard PALSfit License Agreement, fill it out, sign it and send a scanned copy as e-mail to:

Morten Eldrup
Department of Energy Conversion and Storage
Technical University of Denmark

phone: +45 6014 8304
e-mail:PALSfit@risoe.dtu.dk

You will then receive the license key by e-mail.

 
Price
From 15. november 2022, the PALSfit license is free of charge.

The PALSfit license admits at any time installation and execution of all new updates of PALSfit3.

 
Demo version
A demo version of PALSfit3 can be installed and may be used without any license key.
The demo serves to demonstrate the main features of the program but has limited functionality (for example, only the PositronFit part is available, the number of channels and lifetimes are limited etc.).
Data for testing the program are included in the package.

Install Demo Version (PALSfit3_demo version 3.251)

 
Auxiliary programs
Free programs related to PALSfit are available here.

 
Authors
Jens V. Olsen, Peter Kirkegaard and Morten Eldrup
Technical University of Denmark

e-mail: PALSfit@risoe.dtu.dk