This directory contains packages for McStas 2.3 on Linux and Unix systems. We provide Debian packages, RedHat packages, and tar.gz's of binary and source. NOTE!!! The preferred way of installing on Debian or RedHat type systems is by adding our repository!!! Please consult NOTE!!! The rpm's available in our RPM repos are those built on Scientific Linux 6.1 http://www.mcstas.org/download/install_linux/ UPDATE 20160915: This directory further 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. (Get a package from the relevant subfolder of from your rpm/deb repos!) 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