This directory contains an updated component library for McStas 2.3, including a September 2016 version of the
ESS "butterfly" source component and updated MCPL event list support.

Please install the relevant version for your platform "on top" of your existing McStas installation.

The component is a new development with an easier-to-use geometry, centred on the so-called "moderator focal points".

The component DOES NOT implement historical brilliance formulations, it only realises a model of the so-called BF1 design.

For more information, including extended usage instructions and benchmark datasets, please consult this website:
http://ess_butterfly.mcstas.org

The website also contain (currently draft) documents written with Ken Andersen and Luca Zanini, explaining the reasoning
behind changing from the BF2 design to the BF1 design, neutronical calculations and benchmarks. Please note that these are
still in DRAFT status, are expected to be in their final shape around 2016-09-22.


Peter Willendrup
2016-09-15