1. Jet-Met November-7-2002 G. Bernardi LPNHE - Paris Zero-Suppression & Missing E T Compare Data Quality with: - May data = Pre-Shutdown Data, 154k-155k, P10.15 - June-July = Post-Shutdown Data, 157k - 160k, P11.09 + change of 0-suppression 2.5  1.5 sigma after run 158062 -August-October = Post-Mixing Data, 162k - 167k, P11.1x p11.11/12 Data, mid-August to end October

2. Jet-Met November-7-2002 G. Bernardi LPNHE - Paris OLD: June-July vs April-May Data Major change of average missing E T when going from 2.5 to 1.5 sigma zero- suppression cut: From 6-7 GeV to 14-18 GeV, with a wider scattering from run to run. One entry per root-tuple, data from 19 th june till 9 th of July. P11.09 works fine with 2.5 sigma Comparison with April-May Data, p10.15

3. Jet-Met November-7-2002 G. Bernardi LPNHE - Paris OLD: June-July: MET Mean&RMS Major change of average missing E T when going from 2.5 to 1.5 sigma zero- suppression cut: From 6-7 GeV to 14-18 GeV, with a wider scattering from run to run. BUNCH MIXING? Also true for RMS(MET) One entry per root-tuple, data from 19 th june till 9 th of July.

4. Jet-Met November-7-2002 G. Bernardi LPNHE - Paris Conclusions…(from 17 th JULY) Presently difficult to extract useful information from the cells at low energies, due to these warm zones. MET is affected by the lowering of zero-suppression: the analyses will have to recompute MET from cells and tune the cuts to have a similar resolution as before, until the warm zones are corrected in hardware. It seems that a very high cut is now needed to achieve it (> 500 MeV) Probably wiser to go back to a higher threshold (2 or 2.5 sigma), at least until the problem is fixed. Extrapolating from our experience of the comissionning, It is most important to keep cells in the thumbnail for at least a year, so this should be kept in mind when deciding which zero suppression level to use. We favor 2 sigmas, to increase slightly the signal and to avoid a too large increase of the overall noise.

5. Jet-Met November-7-2002 G. Bernardi LPNHE - Paris We start after the fix of Calo bunch mixing. Run 161972, and go up to October 31 st : Run 167191 i.e. about 15000 Files (root-tuples) 77 Million Evnts Corresponding to a delivered LUMI: 39.6 pb -1 recorded 30.0 pb -1 Live fraction 76.0% Presently processed over 40%,  finished this w.e. Info presented on 214 runs: 33.3 Mevts / 12.3 pb -1 p11.11/12 Data, mid-August to end October