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

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

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• 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

June 17th, 2025: McStas and McXtrace 3.5.32 released

What's Changed

Common changes to McStas and McXtrace

• Deployment, platforms and CI
  • [Bugfixes] to Windows conda script and related README by @willend in#1976#1978, #1984, #1985, #1986
  • [CI] Let "autobuild" CI scripts create arm64 debs for mccode.org by @willend in #1981
• Tools:
  • [Feature] mcgui/mxgui: show current instrument name in dialogues by @farhi in #1989
  • [Feature] VSCode McStas/McXtrace grammar extension
    • Update vs code extension by @Lomholy in #1975
    • Small updates to editor, as well as updated installation information by @Lomholy in #1977
  • [Feature] LaTeX math (formulae etc) for mcdoc %Description headers by @willend in #2054
• Code generator/Grammar:
  • [Feature] Unified McStas/McXtrace, c and .py code generators defined from common set of files in mccode/src
    • Unify grammar take2 by @willend in #2008
    • Unify instr y c py: unify our code generators for C and Python by @farhi in #2009
  • [Feature] NEW INHERIT keyword in the component grammar: Allows to mix and match component sections from multiple components to achieve new functionality.
    For an example use see
    • Grammar multiple comp copy extend by @farhi in #2012 (-> INHERIT)
    • FluoPowder in McXtrace
    • https://github.com/mccode-dev/McCode/blob/main/doc/GRAMMAR/ADR-records/ADR_20250612_INHERIT_COMP.md
    • Edits by @farhi and @willend in #2062
  • [Feature] Add ADR (Architectural Design Record) for grammar changes
    • Add doc folder for proposed, accepted, rejected, deprecated, superseded changes of McCode GRAMMAR by @willend in #2064
    • Put in place folder for grammar documentation by @willend in #2070
  • [Feature] The McStas/McXtrace code generators have a new commandline switch --version-num to print the version number only.
  • [Feature] New CLI default for mcstas / mcxtrace: --trace is on (This allows any compiled instrument to run with --trace=0 by @willend in #2010 and #2023)
• Libs and runtime (various minor changes)
  • Add Open_File in header (used from e.g. PowderN) by @willend in #2014
  • Wrap cabs in OpenACC settings by @willend in #2016
  • Swap default trace behaviour to 'enabled' by @willend in #2023
  • cif2hkl: update to solve F^2 for Xrays using latest CrysFML by @farhi in #2021
  • Openacc minor rectifications by @willend in #2027
• MCPL Components
  • [Feature] Update MCPL components for MCPL 2.2.0 features (including stat:sum). by @tkittel in #2046
  • [Feature] Sync MCPL components McStas <-> McXtrace for MCPL 2.2.0 support by @willend in #2019
  • [Feature] Please consult the GitHub discussion on MCPL > 2.0 support in McStas / McXtrace

McStas specific:

• [Bugfix] Source_custom
  • Fixed minor typo in docs by @pablogila in #1980
  • Fixed pulse normalisation for all values of n by @pablogila in #2024
  • Simplified redundant code for the peak integral calculation by @pablogila in #2025
• [Bugfix and feature] Resolution sample/monitor
  • Reso: Updates by @tweber-ill in #1992
  • Add infrastructure to save calculated resolution/covariance matrices by @willend in #1993
  • Sync Res_monitor <-> TOFRes_monitor by @willend in #1995
• [Bugfix] Add mcresplot to debian metapackage by @willend in #2022
• [Bugfix] Monitor_nD pixel id and buffer fix by @mads-bertelsen in #2002
• [Bugfix] Add exit attenuation to Incoherent.comp for finite order scattering by @Lomholy in #2042
• [Bugfix] Updates to Monochromator_bent from @Lomholy by @willend in #2059 and #2058

McXtrace specific:

• [Features and bugfixes] McXtrace fluorescence:
  • McXtrace: fix header doc in fluo sample (powder and SX) by @farhi in #1974
  • McXtrace fluo fix pow 0 by @farhi in #1979
  • McXtrace fluo fix 2 by @farhi in #1988
  • McXtrace fluo fix : fix in powder select - use gaussian line shape by @farhi in #1994
  • McXtrace: samples: fluo: add M-lines via XrayLib Kissel CSb calls by @farhi in #2004
  • McXtrace: samples: fluo: fix again the Fluo share by @farhi in #2005
  • McXtrace add fluo mcdisplay by @farhi in #2015
  • McXtrace fluo add detector 0 by @farhi in #2029
• [Bugfix] Fix compilation of McXtrace Test_PowderN instr by @willend in #2000
• [Bugfixes] McXtrace various example instrument updates by @farhi in
  • #2033, #2034, #2045, #2048, #2051, #2056, #2057
• [Bugfix] cif2hkl: update to solve F^2 for Xrays using latest CrysFML by @farhi in #2021
• [Feature]McXtrace: add SWING BL at SOLEIL by @farhi in #2036

Full Changelog: https://github.com/mccode-dev/McCode/compare/v3.5.27...v3.5.32

April 29th, 2025: McStas and McXtrace 3.5.27 released

Dear all,
McStas and McXtrace release 3.5.27 is now available.
McXtrace installation instructions are found on GitHub .

What's Changed - common McStas/McXtrace highlights:

• [Feature] McStas and McXtrace are now fully on conda-forge also for Windows, since MCPL 2.0 arrived.
  This means that we now recommend to install via this mechanism on Windows. See the instructions for details.
• [Feature] mcrun/mxrun have a new -y switch which runs a given instrument using its default parameters.
• [BUGFIX] mcplot/mxplot should now deal better with negative / very small numbers in 'log' mode plotting.
• [Feature] mcgui/mxgui improved tooltips on the run dialogue.
• [Feature] rootmccode works with newer versions of ROOT
• [BUGFIX] The KISS random number generator was earlier running with systematically different random numbers (and a shorter period) on Windows.
  Identical instruments now run with identical random numbers across platforms, when using identical seed.
• [CI, packaging, platform support] Lots of work behind the scenes for portability, packaging, and improved CI of the code on GitHub.
  Better standard solutions and easier possibility of spotting when/if we make errors!

What's Changed - McXtrace specific highlights:

• [Feature] New components for Fluorescence + Single_crystal and Fluoresence + Powder.
  Come with corresponding new test instruments.

What's Changed - McStas specific highlights:

• [BUGFIX] As reported on mcstas-users, reflective/transmissive polarisers/analysers could sometimes lead to |P|>1.
  This is now fixed by ellimination of "non-up-down" polarisation components when measuring an "up-down" polarisation.
• [Feature] Contributed component Source_custom by @pablogila, useful features for simulatiung e.g. CANS and other pulsed sources.
  Comes with corresponding new test instrument.

April 6th, 2025: Component doc pages back online

We are now in the air with new server hardware.

Among other things this means that component mxdoc pages are back online - by popular demand!

April 5th, 2025: Ongoing webserver upgrade

We are in the process of upgrading the webserver for McStas, McXtrace and other sites. Please bear with us if you experience service interruptions. :-)

February 19th, 2025: McStas and McXtrace 3.5.24 released

Dear all,
McStas and McXtrace release 3.5.24 is now available - McXtrace installation instructons on GitHub .

What's Changed

Important note

• McStas and McXtrace will soon change organisation-name on GitHub - from McStasMcXtrace -> mccode-dev

User interfaces and tools

• [Feature] mcgui/mxgui Let configuration dialogue spawn your EDITOR to edit your local mccode_config.json by @willend in https://github.com/mccode-dev/McCode/pull/1838 (available also by --edit-user-config from mcrun/mxrun)
• [Feature] mcrun/mxrun: New switch --cogen to allow on-demand switch to non-standard code generator. See also interoperability with mccode-antlr below by @willend in https://github.com/mccode-dev/McCode/pull/1851
• [Feature] mcrun/mxrun Solution for picking up code generator from PATH if not found where expected by @willend in https://github.com/mccode-dev/McCode/pull/1840
• [Feature] pygen minor revision: Build importable make() function and call from generic notebook by @willend in https://github.com/mccode-dev/McCode/pull/1827
• [Fix] Support Scintilla editor on Debian with Qt6 by @willend in https://github.com/mccode-dev/McCode/pull/1813
• [Fix] Drop hard-coded check for PyQt5 by @willend in https://github.com/mccode-dev/McCode/pull/1814
• [Fix] No more hidden Perl dependencies! (perl -> python 1-liner readlinkf()) by @willend in https://github.com/mccode-dev/McCode/pull/1824
• [Fix] too-restrictive mcdisplay/mxdisplay instrument line parsing by @g5t in https://github.com/mccode-dev/McCode/pull/1834
• [Fix] Patches for mcdisplay/mxdisplay in Windows from @LelandWH https://github.com/mccode-dev/McCode/issues/1853

Components and instruments

• [Fix] McStas Vertical_bender: Add max iteration criterion for while loop (default 1000). by @willend in https://github.com/mccode-dev/McCode/pull/1815
• [Fix] McStas NCrystal_sample: Remove possible out-of-bounds memory access by @g5t in https://github.com/mccode-dev/McCode/pull/1821
• [Fix] McStas Elliptic_guide_gravity and Pol_mirror: Minor comp revisions, suppresses compilation warnings from clang by @willend in https://github.com/mccode-dev/McCode/pull/1826
• [Fix] McStas SNS_ARCS.instr edits by @willend in https://github.com/mccode-dev/McCode/pull/1838
• [Fix] McStas ISIS_IMAT.instr DEPENDENCY " @NEXUSFLAGS@ " added by @willend in https://github.com/mccode-dev/McCode/pull/1839
• [Fix] McStas Union_master Adjustment of default parameter by @willend in https://github.com/mccode-dev/McCode/pull/1840
• [Fix] McStas Union-related fixes and imports from DMSC school by @willend in https://github.com/mccode-dev/McCode/pull/1841
• [Fix] McStas Elliptical_guide_gravity did not work in GROUPS as it always SCATTERS by @mads-bertelsen in https://github.com/mccode-dev/McCode/pull/1843
• [Fix] Monitor_nD on GPU: Adjustments for coherence between CPU and GPU particle lists by @willend in https://github.com/mccode-dev/McCode/pull/1816

Core simulation toolkit

• [Feature] NeXus: sort comp instances by index and include comp parameter information by @willend in https://github.com/mccode-dev/McCode/pull/1828
• [Fix] Increased stability in NeXus x wide MPI by @willend in https://github.com/mccode-dev/McCode/pull/1811
• [Fix] Portability, Windows + cl.exe: Remove variable length array allocations for issue #1817 by @g5t in https://github.com/mccode-dev/McCode/pull/1819 and https://github.com/mccode-dev/McCode/issues/1818 by @willend in https://github.com/mccode-dev/McCode/pull/1822

Interfaces and interoperability with other codes

NCrystal

• Thanks to @tkittel for ping-pong on this :)
• [Feature] McStas 3.5.24 and later now depends on NCrystal 4.0.0 and later. NCrystal is now available also on Windows! by @willend in https://github.com/mccode-dev/McCode/pull/1848 and https://github.com/mccode-dev/McCode/pull/1855

mccode-antlr

• Thanks to @g5t for ping-pong on this :)
• [Feature] mccode-antlr is an alternative code-generator for McStas and McXtrace - a new development by @g5t and based on ANTLR instead of lex/yacc. The new tool is mainly written in python and thus has a lower barrier for changes in language syntax and code generation. The tool implementations mcstas-antlr and mcxtrace-antlr are thus a candidate implementations to potentially replace the classic mcstas and mcxtrace code generators in the future. Current status is that
  • McStas: mcstas-antlr is fully feature complete wrt. mcstas for CPU simulations and close to complete for GPU simulations
  • McXtrace: Not all instruments will compile using mcxtrace-antlr but basic functionality is in place
  • To try:
    1. Install mccode-antlr from conda-forge or via pip
    2. Adapt your configuration to use e.g. mcstas-antlr by
       • Setting the new --cogen=mcstas-antlr option in mcrun
       • Enable or edit the MCCOGEN field of mccode_config.json using the new Save/Edit configuration in mcgui
       • (The antlr tools default to download comps etc. to an internal cache: Add e.g. -I${MCSTAS} to prefer ingredients fromyour local library)
    3. Use the mcrun-antlr/mxrun-antlr tools provided directly by mccode-antlr

Platform support

• Debian/Ubuntu
  • [Fix] Make hidden numpy dependency explicit also on Debian by @willend in https://github.com/mccode-dev/McCode/pull/1825
  • [Fix] McXtrace meta-pkgs for Debian add libgsl-dev as dependency by @farhi in https://github.com/mccode-dev/McCode/pull/185
• Windows
  • [Feature] NCrystal is now available with McStas on Windows
  • [Info] Windows via cross-compiled .exeinstaller from mccode.org: Please place the MCPL-related .bat files from the extras folder in e.g. c:\mcstas-3.5.24\bin to enable MCPL (May require giving your user 'full access' permissions to the bin folder)
  • [Info] Windows via conda-forge: MCPL is not yet available but expected during the spring

Full Changelog: https://github.com/mccode-dev/McCode/compare/v3.5.16...v3.5.24