1. June 29, 1999 ZEUS Report : 47. DESY PRC 1 ZEUS Status Report: June 1999  A Word on the Spring 1999 e - p Luminosity Run Performance u Physics Highlights From Recent Analyses  A(nother) Guided Tour Along Q2, including Photoproduction of jets and of charm Deep Inelastic Scattering (DIS) production of charm and dijets Inclusive Scattering at the Highest Q2 u Progress on Approved Tracking Upgrades  Straw Tube Tracker  Microvertex Detector u Bring on the Positrons ! Danny Krakauer Argonne National Laboratory

2. June 29, 1999 ZEUS Report : 47. DESY PRC 2 Summary of the 1999 e - p Run  Rapid ramp up to nominal efficiency (as per 1996/1997, w/ short Winter break)  Achieved  70 % efficiency relative to useful lumi.  Improved over 98, approaching 97 record. u Dealt with Coasting Protons problem at the trigger level u Two-Person shift crews Ldt = 11.4 pb -1

3. June 29, 1999 ZEUS Report : 47. DESY PRC 3 About to embark on tour of (quite) recent ZEUS results u A very broad and deep program, that’s also a lot of “fun”. u Some statistics to illustrate the activity:  From January - August, ZEUS physicists will give  105 invited or contributed conference presentations. x  Since last PRC meeting, 5 EPJC articles have been submitted/accepted, 4 more have passed collaboration “readings”, and x more are advanced to pre-reading stage. Many new results approved for public talks - including three or four in this summary.  Last week, an exciting collaboration week with over 30 physics presentations and extended discussions. Many new results approved for public talks - including three or four in this summary. u And now let’s embark on our

4. June 29, 1999 ZEUS Report : 47. DESY PRC 4 Kinematic Range of (x,Q 2 ) Explored at HERA

5. June 29, 1999 ZEUS Report : 47. DESY PRC 5 u Examples of LO processes LO direct x  = 1 LO resolved x  < 1 Additional Variables in Photoproduction

6. June 29, 1999 ZEUS Report : 47. DESY PRC 6 Subjets in photoproduced jets Quark and gluon jets are expected to be different due to different qg and gg couplings. Investigate structure of jets by looking for subjets.

7. June 29, 1999 ZEUS Report : 47. DESY PRC 7 Subjet Multiplicity Subjet analysis senses differences in multiplicity and width of jets:  N jet  quarks   N jet  gluons

8. June 29, 1999 ZEUS Report : 47. DESY PRC 8 Subjet Multiplicity  N jet  Ycut  as   Forward Jets more glue-like

9. June 29, 1999 ZEUS Report : 47. DESY PRC 9 Trijet Photoproduction (leading jet) (2nd jet) (3rd jet) u  3 : scattering angle of th Leading Jet in the 3J CM.  Angular distributions reflective of reaction dynamics (quark/gluon)  In three jet events, the 3rd jet allows identification of fwd/back direction of leading jet in the 3J CM

10. June 29, 1999 ZEUS Report : 47. DESY PRC 10 Low-W photoproduction of Charm Differential cross sections Data lie above NLO calculations Events are tagged by hits in the “44m” tagger - 80 GeV < W < 120 GeV

11. June 29, 1999 ZEUS Report : 47. DESY PRC 11 From D *  in DIS FINAL

12. June 29, 1999 ZEUS Report : 47. DESY PRC 12 From D *  in DIS F 2 C / F 2 x Contribution of charm in DIS grows with Fraction of charm increases with decreasing x.

13. June 29, 1999 ZEUS Report : 47. DESY PRC 13 Measurement of  s in dijet DIS Select dijet events with : Region of small experimental and theoretical uncertainties Compare measured dijet ratio to NLO calculations (DISENT) Measure  s from dijet cross section  2+1 and ratio:

14. June 29, 1999 ZEUS Report : 47. DESY PRC 14 Searches For New Physics in e-p Data in Good Agreement w/ SM Search for Isolated High P t Muons or Electrons in e - p Study of High (x,Q 2 ) e - p NC DIS First 8.6 pb - 1 of 1998/99 One Candidate in First 5.1 pb - 1 of e - p data before lepton cut Exp Bkg = 0.50 after Lepton ID 0.24  0.14 e 0.24  0.03  First 5.1 pb - 1 of 1998 data

15. June 29, 1999 ZEUS Report : 47. DESY PRC 15 High Q 2 Neutral Current DIS

16. June 29, 1999 ZEUS Report : 47. DESY PRC 16 High Q 2 Neutral Current DIS Direct Sensitivity to Z 0 - boson exchange

17. June 29, 1999 ZEUS Report : 47. DESY PRC 17 High Q 2 Charged Current DIS u Comparison of e + p to e - p at high Q 2

18. June 29, 1999 ZEUS Report : 47. DESY PRC 18 High Q 2 Charged Current DIS

19. June 29, 1999 ZEUS Report : 47. DESY PRC 19 Charged Current & high-x quarks u Differences due to quark density and helicity u Potentially, direct extraction of d:u quark ratio and estimates of high Q 2 sea quark distributions…. And… And… And… u Polarization (w/Lumi) will help ….

20. June 29, 1999 ZEUS Report : 47. DESY PRC 20 Looking Ahead to High Luminosity

21. June 29, 1999 ZEUS Report : 47. DESY PRC 21 Subcomponents newly operational in 1999 u Barrel Presampler:  Energy corrections for hadrons and electrons over full detector, with minimal use of MC  BPRE useful for  0 /  separation u Forward Neutron Tracker  Scintillator fingers at 1 0 inside FNC for precise reconstruction of impact point.  Improved P t resolution for t- dependent studies BPRE sampler Forward Neutron Tracker  e-e-

22. June 29, 1999 ZEUS Report : 47. DESY PRC 22 StrawTube Tracker (STT) u Beam-tests at DESY of prototype sector and prototype electronics:  Multiplexing Scheme for digital readout designed, final prototype being produced u STT Short sector production to begin next month, Long sector design complete.  Beamtest of STT, end-to-end, in September

23. June 29, 1999 ZEUS Report : 47. DESY PRC 23 Microvertex Detector (MVD) u Barrel MVD Si acceptance tests, Forward MVD Si prototyping u Cabling and Interconnects - orders soon u Bonding and module production underway at DESY (Halle 1) now. u Progress on readout and trigger… MVD will participate at the Second Level “Global Tracking” (CDT,STT,MVD) trigger.  Much progress on all aspects of project goals. FMVD first prototype, ready for test beam Bonding machine at DESY

24. June 29, 1999 ZEUS Report : 47. DESY PRC 24 End of Talk / Start of Next Run u ZEUS is enjoying a rich variety of Physics Investigations A quick tour through Q 2 with peaks at precision measurements of  s, growing program in heavy flavors, searches for Exotics and measurements of weak-effects in DIS, STILL leaves out the vast majority of an active and growing Physics environment. New results from ZEUS are coming all the time. u ZEUS is ready to maximize collection of ep data before the Upgrade. u Last chance for some detectors and some physics. u Progress on Lumi-Upgrade : Both new Trackers are meeting goals to be ready. The existing trigger and R/O components are ready NOW.