the cleo-c event environment subsystem plans tracking calorimetry particle id muon detector

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


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The CLEO-III DetectorThe CLEO-III Detector


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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.


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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.


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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).


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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


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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).


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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.


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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


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Muon DetectorMuon Detector

Works as in CLEO-III. No changes needed.


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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


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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


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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


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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.


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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


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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.


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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.

the cleo-c event environment subsystem plans tracking calorimetry particle id muon detector

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