I'm wondering if there are any free particle physics datasets out there, for use in teaching, demonstrations, developing analysis techniques etc.. I'm looking for data events e.g. as ROOT trees or in a similar format, together with a standard set of background events and postprocessing, or maybe even a simple framework with detector simulation to create my own events. I'm not looking for the very "raw" data, but something you could do a simple analysis on, like plot the dilepton mass and see resonances. The kind of experiment doesn't matter that much, as its for illustration purposes (can be e+e-, pp, medium or high energy).
Publishing raw data is common in other areas or fundamental (non-applied) research, especially in government-funded astronomy experiments. Imaging my astonishment when I started in this field that you couldn't just download "the data" from www.cern.ch as a torrent :-). For collaboration-political reasons, and because the data is considered too ununderstandable for laypersons, it is tightly controlled by the experiments. Yet, internally, especially on mature collaborations, you often have "the (processed) dataset", "the standard MC", "the standard corrections and uncertainties", and writing a simple analysis (for demonstration, not for publication) boils down to just writing custom code for event selection, so it should be entirely possible for a physics student or even an interested layperson to make a little sense of the data.
So, I believe that at least one of the now closed experiments (LEP, Tevatron, Hera, ...) might have published their framework and data, but I couldn't find anything on the net. Does anyone know of such a case?