Hello again, Apropos my previous request for help with JetFinder... {One of the advantages of being 9 hours ahead... I can answer some (only some) of my own questions before you all wake up.} By explicitIy using hep.physics.jets.AbstractJetFinder etc. I can get JetFinder to work with fastMC tracks Enumeration fastMCe = event.getTrackList().getTracks(); jetFinder.setEvent(fastMCe); (I still have some problems using the Predicate.. though explicitly casting the Object to a Track then get the associated MCParticle it seems to work - is this the right approach?) How do I do jet finding with both charged and neutral "tracks" since LCDEvent seems only to provide these separately? If I try the same thing with MCParticles directly such as (mimicking the example): ParticleVector pv2 = event.getMCParticles(); jetFinder2.setEvent(pv2.particles()); histogram("Njets2").fill(jetFinder2.njets()); It no longer complains about not passing IHep3Vectors but it gives the error: java.lang.ArrayStoreException: at java.util.Vector.copyInto(Vector.java) at hep.physics.jets.AbstractJetFinder.doFindJets(AbstractJetFinder.java:168) at hep.physics.jets.AbstractJetFinder.njets(AbstractJetFinder.java:51) at MCCheck.process(FastMC_anal01.java:269) As usual, any help or suggestions will be gratefully received. Bob -- Robert J. Wilson Professor of Physics Department of Physics Colorado State University Fort Collins, CO 80523 Phone: (970) 491 5033 Fax: (970) 491 7947 Email: [log in to unmask] August 2000 - July 2001: ======================== Institut de Fisica d'Altes Energies Universitat Autonoma de Barcelona E-08193 Bellaterra (Barcelona) SPAIN Phone: (011 34) 93 581.28.32 Email: [log in to unmask] ========================