The CLEO-c Detector

Steve GrayCornell UniversityBESIII WorkshopJanuary 13, 2004

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New Era -> New Needs• Need

• Quality Tracking ANDPrecision EM Calorimetery

• Large 93% – 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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1.5 T now,... 1.0T later

93% of 4p/p = 0.35%

@1GeVdE/dx: 5.7%

@minI93% of 4

E/E = 2% @1GeV = 4% @100MeV

Trigger: Tracks & ShowersPipelinedLatency = 2.5s

Data Acquisition:Event size = 25kBThruput < 6MB/s

CLEO III -> CLEO-c83% of 4

% Kaon ID with 0.2% fake @0.9GeV

85% of 4For p>1 GeV

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CLEO III

(4S)Typical

HadronicEvent

• 10 tracks• 10 showers

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CsIElectromagnetic

Calorimeter(End Cap)

CsIElectromagnetic

Calorimeter

RICH

Drift ChamberOuter Endplate

Drift Chamber EndplateSmall Radius Section

cos = 0.93θ

Interaction Point

CESR

ZD Inner Drift Chamber

3560603-002

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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– z=1 cm; =2/8

• Thin Inner Tube– 0.12% X0

• 60:40 Helium-Propane

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Drift Chamber Performance• Avg. residual 85 m

– Best 65 m

• MC agreement• Momentum Resolution

– p/p=0.7% at 5 GeV/c– p/p=0.3% at 1 GeV/c– MS limited < 1.5 GeV/c

• dE/dx resolution– 5.7% at min Ionizing– K– sep. at low p

Drift Distance (mm)

Res

idua

l (m

)

0 4-4 8-850

100

150

DR3 All Layers

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ZD – Inner Drift Chamber• Charm -> lower

momentum spectrum• Multiple scattering

limited p/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:

– r=5.3 cm – 10.5 cm– 12-15o stereo angle– |cos θ < 0.93

• 300, 10 mm cells

• 1% X0, .8mm Al inner tube

• 60:40 Helium-Propane• 20 m Au-W sense wires• 110 m 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 < 200

• 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

K/

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RICH Detector

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Resolution & PerformanceCLEO III dataD->K without & with RICH cuts.80% eff, 8:1 bkg suppression

K- Separation (Chisq Difference)

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RICH Performance• Designed for B

decay• Excellent for D

decay• K – separation

• Measured in data• D*D0+; D0 K-+

• High efficiency• Low fake rates

• Combine with dE/dx

CLEO-c

B physics

Kaon eff = 0.8Kaon eff = 0.85Kaon eff = 0.9

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CsI Calorimeter• Projective Barrel• Endcaps• 4 photodiode readout• Triple range ADCs• Excellent

– Photon finding– Electron ID – 0 & reconstruction

CsIElectromagnetic

Calorimeter(End Cap)

CsIElectromagnetic

Calorimeter

RICH

Drift ChamberOuter Endplate

Drift Chamber EndplateSmall Radius Section

cos = 0.93θ

Interaction Point

CESR

ZD Inner Drift Chamber

3560603-002

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CLEO CsI at a Glance• ~7800 CsI(Tl) crystals ~5530 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 -> 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 II’s

• Endcaps repackaged for new I.R. superconducting quadrupoles– Thinner DR Endplate & better support design

make less material in front than CLEO II– Only ~40%X0 , about 30% of CLEO II material– “Good Endcap” coverage |cosθ| = 0.85 to 0.93

• Quality solid angle ~25% > 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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’ X, +-

CLEO-c Muon

System

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Trigger• Programmable (FPGA), Pipelined• Track and CsI cluster primitives:

– Tracks (pt>150 MeV/c) – Low, Med, High shower clusters

• Combine to define triggers, e.g.>2 tracks + low shower >99% 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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’ +-; e+e-

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CLEO-c Event Picture

D+ +-

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CLEO-c Event Picture

D0

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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 chamberSize of CLEO: 120–220 Collaborators

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CESR at Cornell

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CLEO III Running for CLEO-c