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The CLEO-c event environment

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CLEO-III drift chamber (DR3) is very well suited to running at lower energies. ... TILE Board Fixes to improve 'Sharing Mode': Added a couple. of capacitors. to ... – PowerPoint PPT presentation

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Title: The CLEO-c event environment


1
CLEO-c Detector Issues
Mats SelenUniversity of Illinois
  • The CLEO-c event environment
  • Subsystem Plans
  • Tracking
  • Calorimetry
  • Particle ID
  • Muon Detector
  • Trigger
  • DAQ
  • Conclusions

2
The CLEO-III Detector
3
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
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 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.

5
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 (10.3o 15.4o).

6
ZD 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
sp/p (Si now) 0.32 0.32 0.35 0.43 0.67
sp/p (Si no r-f) 0.34 0.34 0.39 0.53 0.89
sp/p (ZD) 0.32 0.32 0.35 0.45 0.71
7
ZD Upgrade Plan
  • Low cost quick assembly.
  • Use same (left over) bushings, pins wire as
    DR3.
  • Wont 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.
  • TDCs from spare pool and from muon system.
  • Ten cell prototype has proven that design in
    sound (both mechanically and electrically).

8
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 4p.
  • Large acceptance key for partial wave analyses
    and radiative decays studies.
  • No changes needed.

9
Particle-ID
  • RICH works beautifully!
  • Complemented by excellent dE/dx.
  • Will provide virtually perfect K-p separation
    over entire CLEO-c momentum range.
  • No changes needed.

RICH
dE/dx
p
p
K
10
Muon Detector
  • Works as in CLEO-III.
  • No changes needed.

11
Trigger
  • Tracking Trigger
  • For B 1.5 T, the combined axial and stereo
    trigger hardware is 100 efficient for tracks
    having PT gt 200 MeV/c.
  • When B 1.0 T, we expect to have 100
    efficiency for tracks having PT gt 133 MeV/c.

not real
200 MeV
200 MeV
Tracking Trigger Efficiency versus 1/P(GeV) for
hadrons
Tracking Trigger Efficiency versus 1/P(GeV) for
electrons
12
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.

13
TILE Board Fixes to improve Sharing Mode
Added a coupleof capacitors to back of each
board
14
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
Data Acquisition System
  • Achieved Performance
  • Readout Rate 150 Hz (prior test) 300 Hz
    (expected now) 500 Hz (random trigger)
  • Average Event Size 25 kBytes
  • Data Transfer Rate 6 Mbytes/sec
  • Low dead-time

Trigger Rate 100 Hz
16
Data Acquisition System
  • The biggest challenge will be running on the J/?
    resonance where the effective cross-section is
    1mb.
  • Physics Rate 100-200 Hz if L 1-2x1032
    cm-2s-1 and DEbeam 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 lt 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 (TDCs, for example).
  • Hope to augment this prior to running.

17
Conclusions
  • The CLEO-III detector is a beautiful instrument
    for running at energies around 10 GeV.
  • Its 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 4p.
  • Excellent calorimeter covers 93 of 4p.
  • RICH provides superb particle ID for 80 of 4p.
  • Fully capable trigger DAQ.
  • Best device to ever accumulate data in this
    energy range.
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