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Introduction to McStas, Berlin MC school 2013

Introduction to McStas

Peter Willendrup1,5, Emmanuel Farhi2, Erik Knudsen1,5, Emmanouela Rantsiou3,6, Kim Lefmann4,5

1Physics Department, Technical University of Denmark, Denmark2Calcul Scientifique, Institut Laue-Langevin, France3Laboratory for Developments and Methods, Paul Scherrer Institute, Switzerland4Niels Bohr Institute, University of Copenhagen, Denmark5ESS design update programme, Denmark6ESS design update programme, Switzerland

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Agenda

•An introduction to McStas

•Instruments, components, the neutron ray

•Quick overview of example instruments

•A quick demo

3Introduction to McStas, Berlin MC school 2013

McStas Introduction

GNU GPL license

Open Source

mcstas-users@mcstas.org mailinglistProject website athttp://www.mcstas.org

4Introduction to McStas, Berlin MC school 2013

McStas Introduction•Flexible, general simulation utility for neutron scattering experiments.

•Original design for Monte carlo Simulation of triple axis spectrometers

•Developed at RISØ DTU, KU and ILL, Grenoble.

•V. 1.0 by K Nielsen & K Lefmann (1998)

•Currently 2.5+1 people full time plus students

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GNU GPL licenseOpen Source

neutron-mc@risoe.dk mailinglistProject website athttp://www.mcstas.org

McXtrace - since jan 2009 similar in X-rays

• Synergy, knowledge transfer, shared infrastructure

5Introduction to McStas, Berlin MC school 2013

McStas Introduction

GNU GPL license

Open Source

mcstas-users@mcstas.org mailinglistProject website athttp://www.mcstas.org

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•InstrumentationVirtual experimentsData analysisTeaching

Introduction to McStas, Berlin MC school 2013

What is McStas used for?

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(KU, DTU, schools & workshops)

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Reliability - cross comparisons

P. Willendrup et al., Physica B, 386, (2006), 1032.E. Farhi, P. Willendrup et al., in preparation

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McStas: key concepts

Time (t)

9Introduction to McStas, Berlin MC school 2013

McStas: key concepts

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Introduction to McStas, Berlin MC school 2013

McStas: key concepts

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Introduction to McStas, Berlin MC school 2013

McStas: key concepts Local, internal coordinate system!

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Introduction to McStas, Berlin MC school 2013

McStas: key concepts

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Introduction to McStas, Berlin MC school 2013

McStas overview

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Introduction to McStas, Berlin MC school 2013

Under-the-hood / inner workings

Code generation

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Introduction to McStas, Berlin MC school 2013

Implementation

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Introduction to McStas, Berlin MC school 2013

Instrument file

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Introduction to McStas, Berlin MC school 2013

Component file

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Introduction to McStas, Berlin MC school 2013

Generated c-code

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Introduction to McStas, Berlin MC school 2013

Writing new comps or understanding existing is not that complex...

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Introduction to McStas, Berlin MC school 2013

Example suite: 86 instruments

Introduction to McStas, Berlin MC school 2013

Including user contribs•Well-developed community support

•30-40% of existing and new additions are from users

•No direct refereeing of the code, but these requirements:

•At least one test-instrument

•Meaningful documentation headers (in-code docs)

•Contributions go in dedicated contrib/ section of library

•Natural life-cycle of contrib’s

•Bug-fixes are applied both by contributor and developers

•If contributor becomes unavailable either:

•Many users of comp: Promote to official components, e.g. in optics/

•Few/no users of comp: Move to obsolete/ until next major release

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Introduction to McStas, Berlin MC school 2013

Documentation•Basic use info is available inside comp & instr codes, extracted by perl to html

•100+ page manuals documenting•Metalanguage•What is “under the hood”•Examples of practical use plus advanced features•Assumptions and algorithms applied in the components

•More than 70 example instruments

•Various tutorial and teach yourself solutions are available

Introduction to McStas, Berlin MC school 2013

Enough Talk!Let’s see McStas run?

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Introduction to McStas, Berlin MC school 2013

People

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Introduction to McStas, Berlin MC school 2013

Demo time?