1. T. Burnett C&A 31 July 06 Study of the G4 stepping cut value Toby Burnett and Anthony Nardozza (senior physics student) Are the results at all sensitive to the value(s)? Can we optimize to save CPU time? There has only been one study, by Richard, a long time ago – I have no idea where to find it 

2. T. Burnett C&A 31 July 06 Reference It is described in the Physics Reference Manual, http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/PhysicsReferen ceManual/print/PhysicsReferenceManual71.pdf http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/PhysicsReferen ceManual/print/PhysicsReferenceManual71.pdf Default is 1 mm

3. T. Burnett C&A 31 July 06 Details All-gamma (18MeV- 180 GeV) source GlastRelease v9r7 UW physics Condor farm 200 runs of 5000 incident (1M) for each setting

4. T. Burnett C&A 31 July 06 CPU, accepted difference nominal

5. T. Burnett C&A 31 July 06 Cut=0.01 mm Cut=1.4 mm Representative PSF fits Selection: DC2 classA front Cut=0.1, 0.7 mm PS: I have 16 M v9r9, with new CTB values: same cuts give worse PSF

6. T. Burnett C&A 31 July 06 Summary CPU time: no gain to be achieved by relaxing cut Small (1%) effect on accepted rate needs to be understood, compared with beam test perhaps. No apparent effect on PSF Need to study effective area