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CLEO PAC 28/September/01 M. Selen, University of Illinois
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The CLEO-c event environment
Subsystem Plans Tracking Calorimetry Particle ID Muon Detector Trigger DAQ
Conclusions
CLEO-c Detector IssuesCLEO-c Detector Issues
Mats SelenUniversity of Illinois
CLEO PAC 28/September/01 M. Selen, University of Illinois
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The CLEO-III DetectorThe CLEO-III Detector
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Event EnvironmentEvent 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.
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Tracking SystemTracking 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 PT for a given curvature down
by the same factor.
The silicon detector presents two problems.
It represents a lot of material 1.6% X0 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.
CLEO PAC 28/September/01 M. Selen, University of Illinois
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ZD Upgrade PlanZD 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 (10.3o – 15.4o).
CLEO PAC 28/September/01 M. Selen, University of Illinois
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ZD Upgrade PlanZD Upgrade Plan
Low mass is optimally distributed.1.2% X0, of which only 0.1% X0 is in the
active tracking volume.With DR3, this will provide better
momentum resolution than silicon.P (GeV/c) 0.25 0.49 0.97 1.91 3.76
p/p (Si now) 0.32 0.32 0.35 0.43 0.67
p/p (Si no r-) 0.34 0.34 0.39 0.53 0.89
p/p (ZD) 0.32 0.32 0.35 0.45 0.71
CLEO PAC 28/September/01 M. Selen, University of Illinois
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ZD Upgrade PlanZD 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).
CLEO PAC 28/September/01 M. Selen, University of Illinois
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CalorimeterCalorimeter
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.
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Particle-IDParticle-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
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Muon DetectorMuon Detector
Works as in CLEO-III. No changes needed.
CLEO PAC 28/September/01 M. Selen, University of Illinois
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TriggerTrigger
Tracking TriggerFor B = 1.5 T, the combined axial and stereo
trigger hardware is ~100% efficient for tracks having PT > 200 MeV/c.
When B = 1.0 T, we expect to have ~100% efficiency for tracks having PT > 133 MeV/c.
not real
Tracking Trigger Efficiency versus 1/P(GeV) for electrons
200
MeV
200
MeV
Tracking Trigger Efficiency versus 1/P(GeV) for hadrons
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Trigger…Trigger…
Calorimeter TriggerDuring 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.
Sim
ula
ted
E
ffic
ien
cy
Containedshower
Threshold = 500 MeV
Shared mode
CLEO-II mode
CLEO PAC 28/September/01 M. Selen, University of Illinois
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TILE Board Fixes to improve “Sharing Mode”:TILE Board Fixes to improve “Sharing Mode”:
Added a coupleof capacitors to back of each board
pin number: 8 7 6 5 4 3 2 1
39 pF
15 pF
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Trigger…Trigger…
Global Level-1Flexible enough to design almost any needed
trigger lines.Rate is not an issue (trigger processing is
effectively dead-time-less).
Spares & MaintenanceThe 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.
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Data Acquisition SystemData Acquisition System
Achieved PerformanceReadout Rate 150 Hz (prior test)
300 Hz (expected now)
500 Hz (random trigger)
Average Event Size 25 kBytesData Transfer Rate 6 Mbytes/sec
Low dead-time:
Trigger Rate ~ 100 Hz
CLEO PAC 28/September/01 M. Selen, University of Illinois
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Data Acquisition System…Data Acquisition System…
The biggest challenge will be running on the J/ resonance where the effective cross-section is ~ 1b.Physics Rate ~ 100-200 Hz
if L = 1-2x1032 cm-2s-1 and Ebeam = 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.
CLEO PAC 28/September/01 M. Selen, University of Illinois
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ConclusionsConclusions
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.