1. 1 CLEO PAC 28/September/01 M. Selen, University of Illinois The CLEO-c event environment Subsystem Plans  Tracking  Calorimetry  Particle ID  Muon Detector  Trigger  DAQ Conclusions CLEO-c Detector Issues Mats Selen University of Illinois

2. 2 CLEO PAC 28/September/01 M. Selen, University of Illinois The CLEO-III Detector

3. 3 CLEO PAC 28/September/01 M. Selen, University of Illinois Event Environment Details depend on energy, although generally speaking:  Multiplicities will be lower (about half).  Tracks & showers will be softer.  Physics cross-sections will be higher. ~ 500 nb at the  ” (includes Bhabhas) ~ 1000 nb at the J/  (just resonance)  Relative backgrounds rates will be lower.

4. 4 CLEO PAC 28/September/01 M. Selen, University of Illinois Tracking System CLEO-III drift chamber (DR3) is very well suited to running at lower energies.  We will probably lower the detector solenoid field from 1.5 T to 1.0 T.  This will shift the P T for a given curvature down by the same factor. The silicon detector presents two problems.  It represents a lot of material  1.6% X 0 in several scattering layers.  CLEO-c momentum resolution as already multiple-scattering dominated (crossover momentum is ~1.5 GeV/c).  It seems to be dying from radiation damage.  Performance is degrading fast.

5. 5 CLEO PAC 28/September/01 M. Selen, University of Illinois ZD Upgrade Plan Replace the 4-layers of silicon with an inner drift chamber (dubbed the “ZD”).  Six layers.  10mm cells  300 sense wires.  All stereo (10.3 o – 15.4 o ).

6. 6 CLEO PAC 28/September/01 M. Selen, University of Illinois ZD Upgrade Plan Low mass is optimally distributed.  1.2% X 0, of which only 0.1% X 0 is in the active tracking volume.  With DR3, this will provide better momentum resolution than silicon. P (GeV/c)0.250.490.971.913.76  p/p (Si now) 0.32 0.350.430.67  p/p (Si no r-  ) 0.34 0.390.530.89  p/p (ZD) 0.32 0.350.450.71

7. 7 CLEO PAC 28/September/01 M. Selen, University of Illinois ZD Upgrade Plan Low cost & quick assembly.  Use same (left over) bushings, pins & wire as DR3.  Won’t have to hire stringers (only 300 cells).  Fabrication will be complete by late summer 2002. Will use existing readout electronics.  Preamps build from existing parts & PCBs.  Eight 48-channel data-boards from slightly modified existing spares.  TDC’s from spare pool and from muon system. Ten cell prototype has proven that design in sound (both mechanically and electrically).

8. 8 CLEO PAC 28/September/01 M. Selen, University of Illinois Calorimeter Very well suited for CLEO-c operation.  Barrel calorimeter functioning as well as ever.  New DR3 endplates have improved the calorimeter end-cap significantly (now basically as good as the barrel). The “good” coverage now extends to ~93% of 4 .  Large acceptance key for partial wave analyses and radiative decays studies. No changes needed.

9. 9 CLEO PAC 28/September/01 M. Selen, University of Illinois Particle-ID RICH dE/dx RICH works beautifully!  Complemented by excellent dE/dx. Will provide virtually perfect K-  separation over entire CLEO-c momentum range. No changes needed. K  p

10. 10 CLEO PAC 28/September/01 M. Selen, University of Illinois Muon Detector Works as in CLEO-III. No changes needed.

11. 11 CLEO PAC 28/September/01 M. Selen, University of Illinois Trigger Tracking Trigger  For B = 1.5 T, the combined axial and stereo trigger hardware is ~100% efficient for tracks having P T > 200 MeV/c.  When B = 1.0 T, we expect to have ~100% efficiency for tracks having P T > 133 MeV/c. not real Tracking Trigger Efficiency versus 1/P(GeV) for electrons 200 MeV Tracking Trigger Efficiency versus 1/P(GeV) for hadrons

12. 12 CLEO PAC 28/September/01 M. Selen, University of Illinois Trigger… Calorimeter Trigger  During CLEO-III running the mode of combining analog signals was the same as that used in CLEO- II.  The trigger was designed to operate in a more efficient “shared” mode, but this was not implemented due to relative timing uncertainties between shared signals.  This problem was addressed during the shutdown, and “shared mode” running will hopefully be implemented soon after turning back on. Simulated Efficiency Contained shower Threshold = 500 MeV Shared mode CLEO-II mode

13. 13 CLEO PAC 28/September/01 M. Selen, University of Illinois TILE Board Fixes to improve “Sharing Mode”: Added a couple of capacitors to back of each board

14. 14 CLEO PAC 28/September/01 M. Selen, University of Illinois Trigger… Global Level-1  Flexible enough to design almost any needed trigger lines.  Rate is not an issue (trigger processing is effectively dead-time-less). Spares & Maintenance  The spare situation is not ideal  Only a few spares of each kind  In particular, our 6 TPRO boards seem to be quite fragile and we only have 2 spares.  The Hard metric connectors on most of our boards require a very “trained” hand to swap a board without bending pins.  Hard metric connector technology has improved since we designed the trigger, and we are considering the task of rebuilding several back- planes and retrofitting many of the boards to avoid a serious problem as trigger experts leave.

15. 15 CLEO PAC 28/September/01 M. Selen, University of Illinois Data Acquisition System Achieved Performance  Readout Rate150 Hz (prior test) 300 Hz (expected now) 500 Hz (random trigger)  Average Event Size25 kBytes  Data Transfer Rate6 Mbytes/sec Low dead-time: Trigger Rate ~ 100 Hz

16. 16 CLEO PAC 28/September/01 M. Selen, University of Illinois Data Acquisition System… The biggest challenge will be running on the J/  resonance where the effective cross-section is ~ 1  b.  Physics Rate ~ 100-200 Hz if L = 1-2x10 32 cm -2 s -1 and  E beam = 1 MeV.  We can handle 300 Hz.  With ZD replacing Silicon, the event size could be reduced significantly.  Under almost any assumption, average throughput to tape will be < 6 Mbyte/s, which is compatible with current online system. Although not anticipated, if necessary there are several straight-forward incremental upgrade paths.  Gigabit switch (already bought).  Faster online computer. One potential vulnerability is the shortage of spare readout components (TDC’s, for example).  Hope to augment this prior to running.

17. 17 CLEO PAC 28/September/01 M. Selen, University of Illinois Conclusions The CLEO-III detector is a beautiful instrument for running at energies around 10 GeV.  It’s performance speaks for itself. CLEO-c is a small perturbation of CLEO-III.  Apart from machining the end-plates, the whole ZD upgrade will be done in house using existing parts.  All other detector components are OK “as is”. We are convinced that CLEO-c will be a beautiful instrument for studying charm and resonance physics in the 3-5 GeV regime.  Excellent tracking covers 93% of 4 .  Excellent calorimeter covers 93% of 4 .  RICH provides superb particle ID for 80% of 4 .  Fully capable trigger & DAQ.  Best device to ever accumulate data in this energy range.