1. BESIII Collaboration Meeting Summary
Fred Harris
June 6, 2002
IHEP, Beijing 1

2. 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.

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

4. 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

5. 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.

6. 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

7. For much more physics motivation see talks by:
1.) Li Weiguo
2.) Wang Yifan
3.) Zhao Zhengguo
But forget about discovery of ’ c

8. Progress since last workshop
Machine:
Machine parameters decided.
Preliminary design is nearly finished.
R&D 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
R&D of key systems in progress: SC magnet …

9. Major Upgrades in BESIII
Superconducting magnet
Calorimeter: Cs I with E/E ~ 3 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

10. BESIII Detector

11. MDC structure design.

12. TOF Radius 81cm: 1.0GeV/c K/ time difference is only ~280ps
Two layers, two independent times
Two options:
TOF+TOF
TOF+CCT
Our radius ..
To get so high time resolution, the barrel TOF will be made up of two layers and each layer can give a independent time measurement.
Here two options are considered: one is double TOF, the other is one layer of TOF and one layer of CCT(Cherenkov Correlated Timing Detector). .

13. Comparison of K/ sep. TOF+TOF TOF+CCT
Fig. K / separation for Double TOF
Fig. K / separation for TOF+CCT
This is the comparison of K/pi separation for Double TOF or TOF plus CCT.
If one layer of TOF time resolution is 100ps and one lyer of CCT time resolution is 120ps,
Double TOF’s K/pi separation is to 1.0 GeV.
While for the TOF plus CCT detector, the limit is over 1.1GeV.

14. Figure 5 Configuration of the electromagnetic calorimeter
3. Structure of EMC
Figure 5 Configuration of the electromagnetic calorimeter

15. Figure 1. Effect of electronics noise on the energy resolution from Monte Carlo simulation.γrays 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.

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

17. 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

18. 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

19. The Expected Performance (2)
Muon separation efficiency and contamination from pion versus momentum

20. 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.

21. Important to compare BESIII with CLEOc and B Factories
See talk by Zhengguo
Should add in proposal
We will be asked anyway

22. The detector of BESIII and CLEOc
1.0 tesla option 1
0.4 tesla option 2
magnet
----
layers
m counter
Rich
T (ps) = 80 ps
Double
TOF
2.0%
0.3 cm / E
 E/E(0/0) = 3 %(1 GeV)
z(cm) = 0.3cm/ E
EMC 6%
dE/dx (0/0) = 7 %
0.5 %
P/P (0/0) = 0.5 %(1
1.25 %(1 GeV) @0.4T
MDC
90 m
XY (m) = 130
CLEOc
BES III
Sub-detector

23. Why CLEOC in B Factory Era
Some important measurements at B’s are limited by systematical uncertainty
CLEOC enjoys threshold production, large production cross section, low multiplicity, low BG, high S/B. But limited by statistics

25. Why BESIII in CLEOC Era? BESIII BEPCII CESRC
CLEOC: 2003: y(3770) -- 3 fb-1; 30 M
2004: fb-1; 1.5M DsDs
2005: y(3100) -- 1 fb-1; 1 Billion J/y
BESIII

26. 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 it’s properties.

27. Is BESIII Worth Doing? YES
if L~1033 cm-2s-1 and BESIII is competitive to CLEC, and the commissioning is not too late
Otherwise NOT really

28. Interesting Schedule of CLEOC/BESIII
CLEOC phys. run ?
BESII
BESIII
Construction
Engineer & phys. run
MARKIII
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.

29. Typical Peak Luminosity of CESR-C, BEPC and BEPCII
(1/1030 cm-2s-1)
L(BEPCII)  3 L(CESR-C)  50L(BEPC)

30. 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

31. 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, lists, tech. notes, video conferencing.

32. 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

33. 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.

34. 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 let’s go.
Thanks