December 16th, 2016: Aiming at releasing McStas 2.4 in January

Dear all,

This is just to let you have a sneak preview of what we expect to include in McStas 2.4, which we are planning to release in January 2017:

As always, let us know if you have nice things in your desktop drawers that you would like to contribute! :-)

All the best and seasons greetings,
Peter Willendrup

November 18th, 2016: Video presentation about Mads Bertelsen (NBI) about the new "Union" feature of McStas

Yesterday afternoon at the ESS DMSC, Mads Bertelsen from the Niels Bohr Institute gave an interesting talk about his new "Union" concept for McStas - flyer visible below. The presentation was recorded, and is now available for viewing online at

October 6th, 2016: Use Microsofts "Windows subsystem for Linux" for running McStas under Windows 10!

Partnering with Ubuntu Linux, Microsoft has released the (experimental) feature "Windows subsystem for Linux" (WSL), also known as "Bash on Ubuntu on Windows". Read more here and here.

It turns out that it is relatively straightforward to get McStas running under this new feature - thereby overcoming some of the annoyances of McStas on the Windows platform.

To try it out, please follow the below steps

  1. Install a copy of Windows 10 64 bit
  2. Update it beyond "Windows 10 Version 1607" - aka the "anniversary build"
  3. Enable "developer mode" in settings
  4. Use "turn features on or off" to enable "Bash in windows"
  5. Start bash via the start icon / cmd+esc
  6. Install McStas as usual on a Debian systems. Also remember that you can easily install openmpi etc.
  7. Install and start the Xming X-server
  8. Turn back to your bash and execute

As the feature is considered experimental, you might still find some rough edges, but so far it seems functional and looks very promising!

A few extra tips:

September 21st, 2016: McStas 2.3 on macOS Sierra

If you want to install McStas on the new macOS Sierra, here is a recipe:

  1. Install xcode commandline tools by issuing the command xcode-select --install in a terminal
  2. Install Xquartz from
  3. In your System Preferences, Security & Privacy tab, select to allow installation from Mac App Store and identified developers
  4. Download McStas 2.3 labled for use on El Capitan from and unpack. Open the resulting McStas-2.3-10.11_El_Capitan folder.
  5. Right-click/Ctrl-click McStas-2.3-10.11_El_Capitan.pkg packge and choose Open. (Allow installation when prompted to install package form unidentified developer.)
  6. If you want to use our Python tools
If you upgraded from an earlier Mac OS X release, your installed McStas 2.3 is expected to "survive" that upgrade.

Please report any issue you may find to

September 15th, 2016: Updated component library for McStas 2.3 released, including ESS_butterfly.comp

A updated component library has been pushed to the deb and rpm repositories, plus to the relevant platform folders at If you are on Windows or Mac OS, please simply locate the

folder in the download site, find the relevant mcstas-comps-2.3 package and install it on top of your existing McStas 2.3.

Highlights are

Development is also moving fast on our tools, so we are further planning to release a McStas 2.4 within forseeable future.

Enjoy! :)
Peter Willendrup

April 6th, 2016: McStas 2.3 released!

Here it is: McStas 2.3 is released and ready for download via

Selected, important highligts from the release are listed below. The full list of changes is also available HERE.

IMPORTANT: Please ensure to use our "migration scripts" for McStas 2.0 and 1.12c if you want these to co-exist with 2.3. See

March 7th, 2016: Most mcstas-2.2a instruments available at

If you take a look at this page, you will see that it resembles the examples part of a McDoc documentation page - with one exception: The Run simulation links on the right side of the table points to virtual instruments that may be run through the new McStas web frontend.

As usual, you must have an account at to execute these simulations.

March 3rd, 2016: Announcement of, e-learning platform for neutron scattering

Dear all,

We are happy to officially announce the availability of An e-learning platform for neutron scattering.

The platform was developed with support from NMI3-II (EU-FP7) and features an introductory course in neutron scattering and muon spin spectroscopy. The courses contain a varied selection of interactive learning material using three main technologies

  1. A "WIKIbook" built on Mediawiki with various extensions, e.g. for producing mathematical expressions. It is used as the main source of textbook-material
  2. A Learning Management System (LMS) built on Moodle which , provides exercises, quizzes and evaluation
  3. A web simulator for the McStas neutron instrument simulation program, allowing users to perform virtual neutron scattering experiments on predefined instruments
The platform will be further developed and the learning material expanded in connection with SINE2020 (EU-H2020).

To access the e-learning portal, go to, choose "Get an account" and fill in your personal information.

We hope that you will enjoy this new resource and encourage you to try it out!

On behalf of the team,

Peter Willendrup

For background information on the platform, the teaching material and didactical considerations, please read the related article from Neutron News Volume 24, Issue 1, 2013 - DOI:10.1080/10448632.2013.751795.

- - - - - - -


The main funding for the project is provided by the European Union's 7th Framework Programme for research, technological development and demonstration under the NMI3-II Grant number 283883 and from the European Union's Horizon 2020 research and innovation programme under grant agreement No 654000.

We are also grateful for the financial support recieved from the University of Copenhagen via the "Good Education" and "Education 2016" programmes and from Interreg IV via the OMIC programme.


The people behind the infrastructure are

Project leader: Linda Udby, Associate Professor, Niels Bohr Institute, University of Copenhagen

Platform development leader: Peter Willendrup, Senior Research Engineer, Technical University of Denmark

Course content and didactical developers: Julie Hougaard, PhD student, Niels Bohr Institute, University of Copenhagen & Jesper Bruun, Assistant Professor, Department of Science Education, University of Copenhagen

Content management and development: Pia J. Ray, PhD student & Linda Udby, Associate Professor, Niels Bohr Institute, University of Copenhagen

Software engineer: Jakob Garde, Software developer, Technical University of Denmark

Running server administrator: Jörg Pulz, Technical University of Munich

Learning material:

Contents was contributed by

University of Copenhagen: Kim Lefmann, Linda Udby, Pia Jensen Ray, Julie Hougaard, Lise Arleth, Kell Mortensen, Bente Lebech, Jesper Bruun

Institut Laue-Langevin, ILL: Andrew Wildes, Alain Filhol, Helmut Schober

Technische Universität München: Jörg Pulz, Jürgen Neuhaus

European Spallation Source, ESS: Markus Strobl

February 16th, 2016: Patch for Tk::wrap errors from mcgui

If you ever encounter an error like
Tk::Error###: This shouldn't happen at /usr/share/perl/5.18/Text/ line 84.
 Tk callback for .toplevel
 Text::Wrap::wrap at /usr/share/perl/5.18/Text/ line 84
 main::run_dialog_create at /usr/local/bin/mcgui line 752
 main::run_dialog at /usr/local/bin/mcgui line 824
 main::my_system at /usr/local/bin/mcgui line 985
 main::menu_run_simulation at /usr/local/bin/mcgui line 1320
 main::__ANON__ at /usr/local/bin/mcgui line 1752
 Tk callback for .frame1.button
 Tk::__ANON__ at /usr/lib/perl5/ line 251
 Tk::Button::butUp at /usr/lib/perl5/Tk/ line 175
 (command bound to event)
- then the fix is to replace run_dialog_create in your local mcgui by follwing the instructions described here.

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