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Neutron Monte Carlo ray-trace simulation application

McStas lets you very precisely model a neutron scattering instrument described as a series of components, representing the physical elements of the instrument / Beamline. A source component samples the properties of each neutron ray randomly (Monte-Carlo is used to sample spectrum, direction and spatial origin etc.), and the particle is then propagated through the different instrument components. These later act on the neutron characteristics (position, speed, direction, spin, etc.). Further, one can install detectors along the neutron path to monitor the characteristics and flux of the neutron beam. McStas works on a principle of code-generation (LeX-Yacc based grammar), generating a fully portable ISO-C code to run on a variety of platforms and architectures.


User manual included and available in PDF format from; User tutorial available at



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Verified by

Janet Casey

Verified on

20 April 2004

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Software prerequisites

This entry (in part or in whole) was last reviewed on 1 March 2017.


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