Robert, I've put together two "simple" packages that find jets. One from MCParticles, selecing final state particles and excluding neutrinos ~ronan/jas/AnlJets.java and, one which runs my development version of the Java LCD Fast Monte Carlo (package name hep.lcd.mc.yfast) with neutral clusters simulated for an IDEAL detector with PERFECT calorimeter pattern recognition ~ronan/jas/AnlMCFast.java FMCResolutionChecker.java and ~ronan/jas/yfast/release/*.java I'll try to put up some documentation and output results on the web in the next few days (try looking in http://www.lbl.gov/~ronan/analysis/jets.html later this week or next). Mike P.S. If you show interest the documentation will appear sooner.