BESIII Collaboration

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BESIII Collaboration Meeting Summary Fred
Harris June 6, 2002 IHEP, Beijing
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Before I begin

• I want to thank all the speakers and organizers
  for their hard work and hospitality. I think
  this meeting has been very useful.

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Outline

• 1. Physics
• 2. Progress
• 3. Relationship to CLEOc
• 4. Issues
• 5. Summary

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Physics at BEPCII/BESIII

• Rich source of resonances, charmonium, and
  charmed mesons
• Transition between perturbative and
  non-perturbative QCD
• Charmonium radiative decays are the best lab to
  search for glueballs, hybrids, and exotic states

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Physics to be studied in ?-charm region

• Search for glueballs, quark-gluon hybrids and
  exotic states
• Charmonium Spectroscopy and decay properties
• Precision measurement of R
• Tau physics tau mass, tau-neutrino mass, decay
  properties, Lorenz structure of charged current,
  CP violation in tau decays
• Charm physics including decay properties of D
  and Ds, fD and fDs charmed baryons.

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• Light quark spectroscopy, mc
• Testing QCD, QCD technologies, CKM parameters
• New Physics rare decays, oscillations, CP
  violations in c- hadrons
• ..

• To answer these physics questions, need
  precision measurements with
• High statistics data samples
• Small systematic errors

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For much more physics motivation see talks by
1.) Li Weiguo 2.) Wang Yifan 3.) Zhao Zhengguo
But forget about discovery of ?
c
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Progress since last workshop

• Machine
• Machine parameters decided.
• Preliminary design is nearly finished.
• RD of key systems in progress.
• Passed SLAC review (May 13-15).
• Detector BESIII
• Decision on EM calorimeter CsI crystals
• Detector parameters decided
• Preliminary design in good progress
• RD of key systems in progress SC magnet

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Major Upgrades in BESIII

• Superconducting magnet
• Calorimeter Cs I with ?E/E 3 _at_ 1GeV
• MDC IV with small cells, Al wires, and He gas
• Time-of-flight ?T 80 ps
• Muon detector
• New trigger and DAQ system
• New readout electronics

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BESIII Detector
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MDC structure design.
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TOF

• Radius 81cm 1.0GeV/c K/? time difference is only
  280ps
• Two layers, two independent times
• Two options
• TOFTOF
• TOFCCT

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Comparison of K/? sep.

• TOFTOF

• TOFCCT

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• 3. Structure of EMC

Figure 5 Configuration of the electromagnetic
calorimeter

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• Figure 1. Effect of electronics noise on the
  energy resolution from Monte Carlo
  simulation.?rays pass through MDC and TOF. Energy
  is obtained by the sum of 3 x 3 CsI(Tl) crystals,
  and the sum of direct energy deposit in
  photodiodes with a factor of 40.

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MUON

• Outmost subsystem
• Main function Measure the muons of the end
  particles produced during reaction. Identify
  muons from hadrons (especially pions).

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The RPC Structure (4)

• The two layers of RPC and one layer of aluminum
  pickup strip between the two layers of absorbing
  iron constitute a superlayer

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Monte Carlo Simulation (5)

• The contamination of muon by pion will be
  increased, but to a very limited level.
• In the high momentum range, the contamination of
  muon by pion has no difference

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The Expected Performance (2)

• Muon separation efficiency and contamination from
  pion versus momentum

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Comments from Ian Shipsey

• Happy about our decision to use CsI.
• Worried about our PID.
• To improve on D mixing limits that CLEO-c will
  set will require K - ? misidentification at high
  momentum below the 10-3 level.
• Encourages us to pursue CCT - far simpler than
  RICH.
• We should continue to discuss ways to collaborate.

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Important to compare BESIII with CLEOc and B
Factories

• See talk by Zhengguo
• Should add in proposal
• We will be asked anyway

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The detector of BESIII and CLEOc
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Why CLEOC in B Factory Era

• Some important measurements at Bs are limited by
  systematical uncertainty
• CLEOC enjoys threshold production, large
  production cross section, low multiplicity, low
  BG, high S/B. But limited by statistics

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Why BESIII in CLEOC Era?
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Why BESIII in CLEOC Era?

• Three years CLEOC program does not cover all the
  interesting physics in ?c energy region
• - 2-3 GeV, 2-3 R scan in 2-5 GeV
• - physics of ? and ?(2S)
• - Charmed baryon X
• Need higher statistics for searches (glueball,
  exotica), rare decay, D0-D0bar mixing, CP and
  further improve the precision measurements.
• New discoveries need to be confirmed or
  continued. New type of matters, need high
  statistics to study its properties.

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Is BESIII Worth Doing?

• YES
• if L1033 cm-2s-1 and BESIII is competitive
  to CLEC, and the commissioning is not too late
• Otherwise NOT really

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Interesting Schedule of CLEOC/BESIII

• CLEOC/CESRC
• Wisely seizes the great opportunity perfectly
  fills the gap in the frontier of weak and strong
  interactions
• BESIII/BEPCII
• Natural extension. Will be a unique frontier of
  ?c physics for a decade after CLEOC.

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Typical Peak Luminosity of CESR-C, BEPC and
BEPCII

• L(BEPCII) ? 3?? L(CESR-C) ? 50?L(BEPC)

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BESIII Collaboration

• Beijing University
• Budker Institute of Nuclear Physics
• University of Hawaii
• IHEP
• Nanjing University
• National Central University (Taiwan)
• Shandong University
• University of Science and Technology
• University of Tokyo
• Tsinghua University
• University of Washington

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Important Tasks

• Check detector design.
• Make suggestions.
• Think about organizational structure
• Institutional Board
• Executive Board
• Subdetector groups
• Spokespersons
• Think about your contribution.
• How to meet? How often?
• Set up communication web, email lists, tech.
  notes, video conferencing.

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Issues

• Cs I crystal length
• Magnet choice
• TOF CCT?
• Do K longs in mu counter?
• Measure more than one coordinate in mu counter?
• Manpower
• Schedule
• Money

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• Concerns and Comments
• To achieve high precision, need excellent
  detector to reduce systematic errors.
• We must compare to CLEOc and B-factory
  experiments. Compare on key channels those
  where BESIII has an advantage over B - factories.
• Is the Pid good enough? Can do DCS decays
  cleanly?
• BESIII is comparable to the B-factory
  experiments is difficulty. We need to borrow as
  much technology, experience, software, etc. as
  possible from them and CLEOc.

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• Summary
• BEPC energy region is rich of physics, a lot of
  important physics results are expected to be
  produced from BESIII at BEPCII.
• Detector design has made much progress. Need to
  optimize!
• Prepare for review in Sept.
• Then lets go.

Thanks