The CLEO-c Detector

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The CLEO-c Detector

• Steve Gray
• Cornell University
• BESIII Workshop
• January 13, 2004

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New Era -gt New Needs

• Need
• Quality Tracking
• AND
• Precision EM Calorimetery
• Large 93 DW
• Nearly hermetic
• Full-range Particle ID
• Simulate Alternatives
• Coordinate with
• Storage Ring

• Expect
• High Luminosity
• High Statistics
• Systematics Dominate
• Rare Decays
• Backgrounds Matter
• Fakes
• Feed-down
• Combinatorics

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CLEO III -gt CLEO-c
83 of 4p 87 Kaon ID with 0.2 p fake _at_0.9GeV
1.5 T now,... 1.0T later
93 of 4p sp/p 0.35 _at_1GeV dE/dx 5.7 p _at_minI
93 of 4p sE/E 2 _at_1GeV 4 _at_100MeV
Trigger Tracks Showers Pipelined Latency
2.5ms
Data Acquisition Event size 25kB Thruput lt
6MB/s
85 of 4p For pgt1 GeV
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• CLEO III
• U(4S)
• Typical
• Hadronic
• Event
• 10 tracks
• 10 showers

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Drift Chamber

• Coordinated with IR
• 9796 sense wires
• 14 mm square cell
• 16 inner axial layers
• 31 stereo layers
• Outer cathode
• segmentation
• Dz1 cm Df2p/8
• Thin Inner Tube
• 0.12 X0
• 6040 Helium-Propane

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Drift Chamber Performance

• Avg. residual 85 mm
• Best 65 mm
• MC agreement
• Momentum Resolution
• dp/p0.7 at 5 GeV/c
• dp/p0.3 at 1 GeV/c
• MS limited lt 1.5 GeV/c
• dE/dx resolution
• 5.7 at min Ionizing
• Kp sep. at low p

DR3 All Layers
150
Residual (mm)
100
50
0
4
-4
8
-8
Drift Distance (mm)
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ZD Inner Drift Chamber

• Charm -gt lower momentum spectrum
• Multiple scattering limited dp/p
• No vertexing needed
• Replace silicon with low-mass Z tracker
• Similar mass resolution
• More layers - better track recognition

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ZD Inner Drift Chamber

• 6 stereo layers
• r5.3 cm 10.5 cm
• 12-15o stereo angle
• cos q lt 0.93
• 300, 10 mm cells
• 1 X0, .8mm Al inner tube
• 6040 Helium-Propane
• 20 mm Au-W sense wires
• 110 mm Au-Al field wires
• Outer Al-mylar skin

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ZD Drawing
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Tracking with ZD
P (GeV/c) 0.25 0.49 0.97 1.36 1.91 2.68
Z0 (?) 806 702 684 680 672 667
?p/p () 0.32 0.32 0.35 0.39 0.45 0.56

• ZD Calibration Underway
• Residuals now lt 200 m
• Expect to outperform
• CLEO-c/CESR Project Description

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Cosmic Ray in ZD
June 7, 2003
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CLEO-c Event in ZD
June 7, 2003
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RICH Detector

• LiF Radiators
• Flat and sawtooth
• UV photons (135-160 nm)
• N2 expansion volume
• MWPC photo-detectors
• TEA CH4

LiF radiator
g
K/p
g
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RICH Detector
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Resolution Performance
CLEO III data D-gtKp without with RICH cuts. 80
eff, 81 bkg suppression
K-p Separation (Chisq Difference)
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RICH Performance

• Designed for B decay
• Excellent for D decay
• K p separation
• Measured in data
• D?D0p D0? K-p
• High efficiency
• Low p fake rates
• Combine with dE/dx

Kaon eff 0.8 Kaon eff 0.85 Kaon eff 0.9
B physics
CLEO-c
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CsI Calorimeter

• Projective Barrel
• Endcaps
• 4 photodiode readout
• Triple range ADCs
• Excellent
• Photon finding
• Electron ID
• p0 h reconstruction

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CLEO CsI at a Glance

• 7800 CsI(Tl) crystals 5?5?30 cm3 (16X0)
• 4 photodiode readout w/local preamps
• 229 crystals have 1 turned off (too noisy)
• 10 crystals have 2 turned off (6 in endcap)
• 0 have 3 or 4 turned off.
• 7 dead crystals in CLEO III (all in endcaps, 5
  near inner or outer radii)
• External summation/pulse shaping TDC
• Total noise per crystal is 0.5 MeV incoherent
  0.2 MeV coherent
• Light output losses calibrate away

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CLEO II -gt CLEO III
Barrel unchanged
TF removed, RICH inserted
DR lengthened narrowed Endplate material
thinned
Endcap repackaged Pushed back 7 cm
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CsI for CLEO III CLEO-c

• Barrel unchanged from CLEO II
• But DR/Particle ID changes increase minimally
  obstructed barrel from 70 to 80 of 4?
• Good Barrel is 14 bigger than CLEO IIs
• Endcaps repackaged for new I.R. superconducting
  quadrupoles
• Thinner DR Endplate better support design make
  less material in front than CLEO II
• Only 40X0 , about 30 of CLEO II material
• Good Endcap coverage cos? 0.85 to 0.93
• Quality solid angle 25 gt than CLEO II
• New digitizing electronics

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CsI Performance
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Lessons from the Calorimeter

• Endcaps reconfigured for CLEO III
• Many crystals had lost signal with age
• Glue joint had opened up
• Endcap crystals reglued
• Unable to fix barrel glue joints
• Material matters
• Much improved Endcap performance

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CLEO-c Muon System
y ? y X, y ? mm-
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Trigger

• Programmable (FPGA), Pipelined
• Track and CsI cluster primitives
• Tracks (ptgt150 MeV/c)
• Low, Med, High shower clusters
• Combine to define triggers, e.g.
• gt2 tracks low shower
• e gt99 for hadronic events
• For CLEO-c
• Reduce med high thresholds
• Add new neutral-only triggers
• Implemented Tile Sharing

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Data Acquisition

• VME FastBus front ends
• Designed for 1 kHz 4 MB/sec
• Achieved 500 Hz 6 MB/sec
• Several upgrades completed
• A few remain for Spring 2004

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Summary

• New era of high luminosity makes new demands on
  the detector.
• The CLEO-c Detector is state of the art,
  understood at a precision level, now taking data
  in the charm region.

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Credits

• Calorimetry - Brian Heltsley
• DAQ - Tim Wilkson
• Tracking - Karl Ecklund, Dan Peterson
• Trigger - Topher Caulfield

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y ? y pp- y ? ee-
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CLEO-c Event Picture D ? K pp-
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CLEO-c Event Picture D0 ? Kp
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CLEO History

• CLEO I (1979-89)
• CLEO II (1989-95)
• CsI calorimeter
• CLEO II.V (1995-99)
• Silicon Vertex Detector
• CLEO III (2000-03)
• RICH Particle ID
• New IR tracking Silicon, Drift Chamber
• CLEO-c (2003-??)
• Silicon replaced by ZD inner drift chamber

Size of CLEO 120220 Collaborators
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CESR at Cornell
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CLEO III Running for CLEO-c