CLEO-c Detector Issues Mats Selen University of Illinois

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

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

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

Tracking System l CLEO-III drift chamber (DR 3) is very well suited to running at lower energies. ðWe will probably lower the detector solenoid field from 1. 5 T to 1. 0 T. ðThis will shift the PT for a given curvature down by the same factor. l The silicon detector presents two problems. ðIt represents a lot of material Ä 1. 6% X 0 in several scattering layers. Ä CLEO-c momentum resolution as already multiple-scattering dominated (crossover momentum is ~1. 5 Ge. V/c). ðIt seems to be dying from radiation damage. Ä Performance is degrading fast. CLEO PAC 28/September/01 M. Selen, University of Illinois 4

ZD Upgrade Plan Replace the 4 -layers of silicon with an inner drift chamber (dubbed the “ZD”). ð Six layers. ð 10 mm cells ð 300 sense wires. ð All stereo (10. 3 o – 15. 4 o). CLEO PAC 28/September/01 M. Selen, University of Illinois 5

ZD Upgrade Plan l Low mass is optimally distributed. ð 1. 2% X 0, of which only 0. 1% X 0 is in the active tracking volume. ðWith DR 3, this will provide better momentum resolution than silicon. P (Ge. V/c) sp/p (Si now) sp/p (Si no r-f) sp/p (ZD) 0. 25 0. 32 0. 34 0. 32 0. 49 0. 32 0. 34 0. 32 0. 97 0. 35 0. 39 0. 35 1. 91 0. 43 0. 53 0. 45 CLEO PAC 28/September/01 M. Selen, University of Illinois 3. 76 0. 67 0. 89 0. 71 6

ZD Upgrade Plan l Low cost & quick assembly. ðUse same (left over) bushings, pins & wire as DR 3. ðWon’t have to hire stringers (only 300 cells). ðFabrication will be complete by late summer 2002. l Will use existing readout electronics. ðPreamps build from existing parts & PCBs. ðEight 48 -channel data-boards from slightly modified existing spares. ðTDC’s from spare pool and from muon system. l Ten cell prototype has proven that design in sound (both mechanically and electrically). CLEO PAC 28/September/01 M. Selen, University of Illinois 7

Calorimeter l l l Very well suited for CLEO-c operation. ðBarrel calorimeter functioning as well as ever. ðNew DR 3 endplates have improved the calorimeter end-cap significantly (now basically as good as the barrel). The “good” coverage now extends to ~93% of 4 p. ðLarge acceptance key for partial wave analyses and radiative decays studies. No changes needed. CLEO PAC 28/September/01 M. Selen, University of Illinois 8

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

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

Trigger l Tracking Trigger ðFor B = 1. 5 T, the combined axial and stereo trigger hardware is ~100% efficient for tracks having PT > 200 Me. V/c. ðWhen B = 1. 0 T, we expect to have ~100% efficiency for tracks having PT > 133 Me. V/c. 200 Me. V not real Tracking Trigger Efficiency versus 1/P(Ge. V) for electrons Tracking Trigger Efficiency versus 1/P(Ge. V) for hadrons CLEO PAC 28/September/01 M. Selen, University of Illinois 11

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

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

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

Data Acquisition System l Achieved Performance ðReadout Rate 150 Hz (prior test) 300 Hz (expected now) 500 Hz (random trigger) ðAverage Event Size 25 k. Bytes ðData Transfer Rate 6 Mbytes/sec l Low dead-time: Trigger Rate ~ 100 Hz CLEO PAC 28/September/01 M. Selen, University of Illinois 15

Data Acquisition System… l The biggest challenge will be running on the J/ resonance where the effective cross-section is ~ 1 mb. ðPhysics Rate ~ 100 -200 Hz if L = 1 -2 x 1032 cm-2 s-1 and DEbeam = 1 Me. V. Ä We can handle 300 Hz. ðWith ZD replacing Silicon, the event size could be reduced significantly. ðUnder almost any assumption, average throughput to tape will be < 6 Mbyte/s, which is compatible with current online system. l Although not anticipated, if necessary there are several straight-forward incremental upgrade paths. ðGigabit switch (already bought). ðFaster online computer. l One potential vulnerability is the shortage of spare readout components (TDC’s, for example). ðHope to augment this prior to running. CLEO PAC 28/September/01 M. Selen, University of Illinois 16

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