McXtrace - Monte Carlo Xray Tracing, is a joint venture by

Our code is based on technology from

Code repository (shared with 'McStas') is located at github.com/mccode-dev

For information on our progress, please subscribe to our user mailinglist..

To download the latest release: download area
For installation instructions :

McXtrace 3.x installation

For a quick list of the available commands: commands

Recent McXtrace News

Migrating from McXtrace 1.x to 3.x? - Use the wiki-based guides

April 13th, 2026: McXtrace and McStas 3.6.14 released

Installation instructions

For McXtrace go to The McXtrace install page on GitHub
For McStas go to The McStas install page on GitHub

What's Changed
(Selected items, please consult the GitHub changelog for full set)

New comps/instruments

Adding the ILL SANS instrument 'SAM' by @nmgm in #2388

New tool feature: NeXus scans become entries in one common HDF file

Prototype solution to allow 'append' mode for datasets by @willend in #2376

Various updates to instruments/components/data files

Fix Union mcdisplay bugs by @Lomholy in #2294
Fix to MPI-mode use of Brilliance Transfer calculation. by @willend in #2300
Minor instrument and comp updates, McStas by @willend in #2332
More %Example tests for McStas instruments by @willend in #2333
More additions of McStas %Example lines by @willend in #2337
Update of McXtrace Incoherent_process comp from EBK branch by @willend in #2338
Add more %Example lines to McStas instruments by @willend in #2341
Add Test instrument for Be-filter models by @willend in #2349
Re-enable a few tests on the nightlies by @willend in #2364
ESS_butterfly: Wrap all printf / fprintf in MPI_MASTER( ); by @willend in #2372
Updated Rubredoxin lau file from @aaronfinke by @willend in #2384
Updated Example values following updated Rubredoxin.lau by @willend in #2386
Adapt Guide_m interface -> style of Guide_gravity parameters by @willend in #2389
McStas Monitor_nD “nexusbins” only in listmode by @willend in #2387
Mono bent complex string parsing by @Lomholy in #2395

Various tool improvements

mctest / timeout system - ensure to kill underlying processes by @willend in #2363
Add timers for maximal compile / runtime in mctest by @willend in #2356
Add hints for alternative mcdisplay visualisation in Jupyter... by @willend in #2353
mcrun -L list was broken, fixed here by (re-)calculating number of elements … by @willend in #2377
Changed (hard-coded) mcgui 3D visualiser to be webgl-classic by @willend in #2381
On Windows use psutil for probing number of available cores in MPI by @willend in #2367

Other changes

Please consult the GitHub changelog

Fixes to various bugs
LaTeX in doc headers
Clang-format formatting of component syntax
Various updates to project infrastructure: PR template, CI etc.
Various GPU related fixes

New Contributors

@nmgm made their first contribution in #2388

Full Changelog: v3.6.5...v3.6.14

March 31st: First circular: PHOTONS AND NEUTRONS REALISTIC ARTIFICIAL INTELLIGENCE DATASETS (PaNRAID)

Dear Colleagues,

In collaboration with the French DIADEM Academy, we invite interested participants to attend the following course in September:

PHOTONS AND NEUTRONS REALISTIC ARTIFICIAL INTELLIGENCE DATASETS (PaNRAID)

Dates: 21-25 September
Location: Île d’Oléron, France

Objective

The course will develop an integrated approach for generating synthetic data for supervised learning. This approach combines multi-scale materials simulations (DFT, MD, XAS spectroscopy) with comprehensive digital twins of experimental X‑ray and neutron facilities, explicitly accounting for instrumental effects and experimental artefacts.

Intended audience

Doctoral students
Postdoctoral researchers
Faculty and teaching-research staff
Researchers and research engineers

Further information and pre-registration: https://formation.pepr-diadem.fr/formation-panraid

Attached are PDF flyers in French and English.

Best regards,
Peter Willendrup

March 28th, 2026: McXtrace 1.x and McStas 2.x formally out of support

Dear all,

We have decided to formally declare that we no longer support McXtrace 1.x and McStas 2.x, so user issues with these released will from now on always prompt us to request that you upgrade.

If you are still running such an old release, please upgrade and port your comps/instruments using the information in the use the wiki-based porting-guides

We are of course at your service if you have issues porting your existing code, please create a GitHub issue .

January 7th, 2026: McStas and McXtrace 3.6.5 released

McStas and McXtrace release 3.6.5 is now available.
McXtrace installation instructions are found on GitHub .

What's Changed - Main Changes:

Bugfixes, new features, all common to McStas and McXtrace:

macOS bundles in 3.6.1 did not actually install that version but something earlier. Fixed by pinning in yml file, @willend in #2285
PDF manuals had wrong version numbers, @willend in #2285
Allow mcrun / mcdisplay to run / visualize without access to .c/.instr by @willend in #2281
mcgui/mxgui editable font colors, handle long filenames without extreme window resizing by @willend in #2275
Fix cross-platform sort-order issue in PowderN by @willend in #2272
Platform-independent reflection list sort in Single_crystal by @willend in #2273
mcrun/mxrun: feature addition - scan by seed by @willend in #2276
Add mcplot toggle to "plot 1D-curves from 0-value" in linear mode by @willend in #2278
Add commentstring to vim editor by @Lomholy in #2284