Welcome to the home page of the TAS software package

• Introduction
• References
• Copyright
• Technical notes
• Downloading

PkFit [1,2] - a user friendly software for MacOS classic, OpenVMS and UNIX computers - is intended for the data processing of neutron Three-Axis Spectrometers (TAS). Inelastic, quasi-elastic or elastic spectra are fitted by a linear background plus a series of peak functions. The program offers several build-in peak functions but the user may add its own peak shapes through plug-in routines. The model can include the Bose factor, the kf or ki correction, the neutron absorption and the convolution of the signal with a one-dimensional or a four-dimensional resolution function. The later is calculated from the configuration parameters of the spectrometer through the help of the Cooper-Nathans method [3] or the Popovici method [4]. Fast 4D integration is performed by means of new methods, one based on a Monte-Carlo integration technique and the other based on a Gaussian approximation.

Filing - a user friendly software for MacOS classic, OpenVMS and UNIX computers - is intended for the data file handling of neutron Three-Axis Spectrometers (TAS). It makes it possible:

• to combine (i.e. add or subtract with optional weights) equivalent data files (i.e. files with compatible scan variables and resolution parameters)
• to group scan points
• to change the resolution parameters and save them to a file in the ILL TAS format,
• to concatenate a free format data file and a parameter file into a single file in the ILL TAS format,
• to plot several data files on the same graph,
• etc.

RESTRAX [2] - a user friendly software for OpenVMS and UNIX computers - is intended for the calculation of resolution functions, phonon-scan profiles and Bragg widths for neutron three-axis spectrometers (TAS). It combines the "front end" of the older program RESCAL with the much more recent TRAX code [4] and with newly developed Monte Carlo simulation routines.

Using the efficient transfer matrix formalism [4], TRAX is free of the rather simplifying assumptions of the classical Cooper & Nathans formalism [3] and permits to take into account focusing monochromators and analyzers as well as spatial beam collimation. The Monte Carlo simulation provides even more precise description of the resolution function and allows to calculate scan profiles considering general phonon dispersion branches. Thus, the simulated scan profiles can approach the experimental data almost perfectly and be used in data fitting, e.g. PkFit.

1. A.Bouvet and A.Filhol, User's manual of PkFit, ILL report 95BO21T, (1995).
   A.Bouvet, A.Filhol and J.Kulda, Nuclear Instr. and Meth. in Phys. Res. A (1997) in press.
2. J.Saroun and J.Kulda, User's manual of <code>RESTRAX,</code> ILL report 96SA08T, (1996).
3. M.J.Cooper, R.Nathans, Acta Cryst. A23, 357 (1967).
4. M.Popovici, Acta Cryst. A31, 507 (1975).
   M.Popovici, A.D.Stoica and I.Ionita, J.Appl.Cryst. 20 (1987) 90.
   M.Popovici et al., Nuclear Instr. and Meth. in Phys. Res., A338 (1994) 99.
5. The present version is inspired by routines from:
   PKFIT by P. Hullah, P. Frings, M. Alba, A. Bouvet, an ILL software for VAX-VMS computers.
   RESCAL by M. Hargreave, P. Hullah and P. Frings, an ILL software for VAX-VMS computers.
   RESCAM by J. Kulda, an ILL software for VAX-VMS computers.
   RESTRAX by J. Saroun and J. Kulda, an ILL software for OpenVMS and UNIX workstations.
   TRAX by M. Popovici, A.D. Stoica and I. Ionita, described in detailed in reference 3.

The TAS software package has been developed at the ILL (Institut Laue Langevin, Grenoble, France) by A.Bouvet, A.Filhol, J.Kulda and J.Saroun. They are freely available for non-commercial use. They are copyrighted by the Institut Laue Langevin. This software package is provided "as is" with no warranty.

PkFit is based on the original code of P.Hullah [4]. The authors substantially improved it and introduced new features (1D/4D resolution calculation, user defined peak functions, etc.). The old sources have been converted to FORTRAN 77 and re-organized with the help of the MPW environment so as to be more easily adaptable to different computers.

The Macintosh version is compiled with the Language Systems FORTRAN, uses the Apple's toolbox for a convivial interactivity and the TSiGraphics library for graphics. PkFit can be used on any Macintosh computer running MacOS 7.0 or higher. However the use of powerful hardware (a PowerPC processor or, at least, a MC680x0 processor plus a floating point unit) is advisable if the 4D resolution has to be used. For example fitting a delta peak (Monte-Carlo integration) on a 12 point scan takes approximately 5 minutes on a PowerBook 540 (processor 68040, no floating point unit) while on a PowerMac 7200/90 (PowerPC processor) it takes only a few seconds.

The OpenVMS version and the UNIX version are based on the freeware library PGPLOT for graphics and dialogues and have been compiled and linked on:

• Dec-alpha Open-VMS
• HP9000 series 700 - UNIX
• Silicon Graphic on IRIX 5.3

Installation guides

The installation guides of the TAS software-package are available online for the Macintosh versions and for the VMS/UNIX versions and in the form of the text files installmac.txt and install.txt respectively, on the anonymous ftp server ftp.ill.fr/pub/tas/pkfit/appl.

Software-packages and sources

The TAS software-package for different platforms and different operating systems is available

Tutorials and Manuals

The installation guide and the tutorials of the TAS software package can be:

• obtained from the ILL library (Internal report 97BO04T and 97BO05T for respectively the MacOS and the UNIX/VMS)
• read online within your browser.

The manual of PkFit v2.3 for the Macintosh can be:

• obtained from the ILL library (Internal report 97BO03T)
• downloaded at the anonymous ftp serveur "ftp.ill.fr/pub/tas/pkfit/doc/" in the form of a 1254 kb binhexed PDF file, the contents of which can be viewed with the help of Adobe Acrobat Reader v2.0 or higher.
• read directly the PDF file within your browser.

The manual of RESTRAX v4.1 for the VMS/UNIX can be:

• obtained from the ILL library (Internal report 96SA08T)
• downloaded at the anonymous ftp serveur "ftp.ill.fr/pub/tas/pkfit/doc/" in the form of a 526 kb binhexed PDF file, the contents of which can be viewed with the help of Adobe Acrobat Reader v2.0 or higher.
• read directly the PDF file within your browser.

Note that the RESTRAX program is available separately on the anonymous ftp server ftp.ill.fr/pub/tas/restrax41

Created by
Alain Bouvet and Alain Filhol