BESIII Physics andBESIII Physics and

Detector OverviewDetector Overview

International BESIII Workshop

Weiguo Li

IHEP, Beijing, Oct. 13, 2001

• BES Detector and Physics Achievements

• Physics at BEPCII/BESIII

• BESIII Detector Overview

• Summary

BESII Detector and physics achieved

VC: xy = 100 m BTOF: T = 180 ps (>330 ps)MDC: xy = 250 m BSC: E/E= 20 % ,z= 3.0 cm dE/dx= 8.4 % counter: z = 5.0 cm

DAQ readout < 10 ms

Major parameters of the BES detector performance

Detector Major para. BESI BESII VC x,y (m) 200 100 MDC xy (m) 200-250 ~220 p/p (%) 1.78 (1+p2) 1.7 (1+p2) dE/dx(%) 7.9 8.4BTOF T (ps) 375 180 BSC E/E (%) 23.8 20.3 z (cm) 4.5 3.0Muon z (cm) 5.0 5.0DAQ dead time/event (ms) 20 <10

BESII from 1996

Data Collected with BESI and BESII Ecm

(GeV)Physics BES Data Other Lab.

Data

3.10 J/ 7.8106 8.6106

3.69 (2S) 3.9106 1.8106

4.03 1.0105 LEP

4.03 DS, D 22.3 pb-1 CLEO

3.55 m scan m 5 pb-1

2-5 R scan R value,

QED, (g-2)6+85 points 2, MarkI

Crystal BallPluto……

3.1 J/ 5107

World J/ and (2S) Sample (106)

J/ (2S)

05101520253035404550

MarkIII DM2 BESI BESII0

0.5

1

1.5

2

2.5

3

3.5

4

MARKI MarkII MarkIII CrystalBall

BESI

Korea (3)

Korea University Seoul National University

Chonbuk National University

Japan (4)

Nikow UniversityTokyo Institute of Technology

Miyazaki UniversityKEK

USA (4)

University of HawaiiUniversity of Texas at Dallas

Colorado State University Stanford Linear Accelerator

Center

UK (1)Queen Mary University

China (15)IHEP of CAS

Univ. of Sci. and Tech. of ChinaShandong Univ., Zhejiang Univ.

Huazhong Normal Univ. Shanghai Jiaotong Univ.

Peking Univ., CCAST Wuhan Univ., Nankai Univ.

Henan Normal Univ.Hunan Univ., Liaoning Univ.

Tsinghua Univ., Sichuan Univ.

BES Entries in PDG 2000BES Entries in PDG 2000

Citations of BES Citations of BES PapersPapers

Topics Citations

BES detector 42

τ 170

J/ψ 82

ψ’(хc) 146

D 、 DS 51

R 6

Total 492

•Precise τ mass measurement MeV/c2

•2-5 GeV R measurement, better prediction for Higgs mass, 61 90 GeV, upper limit 170 210 GeV

•J/ψ physics, hadron spectroscopy, search for glueball, hybrids and exotics

•ψ(2s) physics, new measurements of ψ(2s) and c decays, 15% rule, suppression

•DS 、 D physics, leptonic, semileptonic and absolute

Brs;

High Lights of BES Physics Results

200180160190961776 ..

...

Recent preliminary results:

• Study of the structure around 1.7 GeV mass region

in J/ K+K- , to be 0++ state

• Systematic study and PWA analysis of J/

+-, K+K- , +-, K+ K- , +-, K+K-

• Analyses the properties of from J/ +-

• Study of excited baryonic states (N*, *…)

- Pure isospin 1/2 -Large branching ratio ~10-3 More results are expected with 50M J/ events

First Measurement of B((2S)+-)(hep-ex/0010072))

• B((2S)+-) = 2.710.43 0.55 (BESI)

• Test of universality: Bee B B /0.3885 Bll

Bee B B /0.3885 8.8 1.3 10.3 3.5 7.0 1.1 1.4• Obtain tot

PDG: ee = 2.12 0.18 keV

tot = ee/Bll = 252 37 keV

Improve the parameters of (2S)

, B(h), B(+ -), B(+-J/)B(+-X)

Scan of (2S) peak 24 energy points between 3.67 and 3.71 GeV

Int. L = 760 nb-1-1

Running Plan before 2004

BEPC will take data with BESII at least until 2004

- 12 M (2S) events/year

- Precision measurement of R in 2-3 GeV

- (3770)?

Afterwards, a long shutdown will be scheduled for the installation of BEPC II.

Physics to be studied at -charm region

Search for glueball, quark-gluon hybrid and exotic states;

Charmonium Spectroscopy and decay properties;

Precision measurement on R value;

Tau physics: tau mass, tau-neutrino mass, decay pro

perty, Lorenz structure of charged current, CP violatio

n in tau decays …

Charm physics: including decay properties of D and

Ds, fD and fDs , D0 –D0 mixing and CP violation…

To answer these physics questions, key issue is precision measurements with

• High statistics data samples • Small systematic errors

Future development of BEPC/BES:• High luminosity machine

• High performance detector:– adapts to high event rate – provides small systematical errors

The Shortcomings of BES II Detector

• Poor energy resolution for electrons and photons;

• Marginal charged track momentum resolutions;

• TOF counters too wide, multiple hits in one counter;

• Information from endcap detector is not sufficient for

phys. analysis;

• Endcap not easily openable to fix detector problems;

• Muon coverage too small.

From BESII to BESIII

Upgrades Needed for BEPCII/BESIII

BEPCII with multi bunches and smaller beam size,

BES needs:

• Upgrade DAQ system with pipeline scheme, to accommodate a factor of more than 200 event rate;

• As the beam size (Z) reduced from 4-5 cm to 1-1.5 cm, there is room to further improve TOF time resolution.

Generally speaking, as the statistical errors become smaller

with larger samples at BEPCII, a better detector is needed

to improve the systematic errors, BESIII will be almost

completely a new detector.

Physics at BEPCII/BESIII

• Rich 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

Expected Event Rates/Year at BES III

Particle Energy Single Ring （1.2fb

-1 ）Double Ring (

4fb-1)

D0 ’’ 7.0106 2.3107

D+ ’’ 5.0106 1.7107

DS4.14GeV 2.0106 0.72107

+- 3.57GeV3.67GeV

0.6106

2.91060.2107

0.96107

J/    1.6109 6109

’    0.6109 2109

J/ψ Physics

1. Glueball search

criteria for glueballs:

• no place in nonet

• enhanced production in gluon rich processes

• decay patters incompatible with states

• reduced couplings

• masses, quantum numbers consist with lattice QCD

qq

Candidates for glueballs:

f0(1500), fj(1710), (2230) , etc.,

qq

Red ordinary

Green interesting

non- states

Black other states not fi

tting in

qq

qq

qq

Lattice QCD Numerical Calculation of Glueball Masses

0++

IBM 1740 71 MeV (1994) 1632 49 MeV (1998)

UKQCD 1568 89 MeV (1993) 1611 30 160 MeV (1998)

improved 1600 100 MeV (1997) 1730 50 80 MeV (1999)

IHEP(Wu) 1757 100 86 MeV (2001)

2++

Meachel 2332 88 MeV (1989)

UKQCD 2270 100 MeV (1993)

IBM 2359 128 MeV (1994)

Morningstar 2140 45 MeV (1997)

Morningstar 2400 25 120 MeV (1999)

IHEP(Wu) 2417 84 117 MeV (2001)

2. Hunting for hybrids

Searching for states with exotic quantum numbers,

0+-, 0--, 1-+, 2+-, 3-+,……

J/ψ x, x or 5, or 0, or 3J/ψ x, x (1300) or a1(1260) or KK1(1400)with (1300) and a1(1260) decay to

3. Other interesting topicsNature of f0(980)

Searching for glueballs and hybrids throughψ(2s) c

producing J/ψ x, x 0,

X are mixing of f0(980), a2(1320), (1390), (2300), here (1390) is 1-+

state

Searching for 1-+ state

ψ(2S) Physics

BESII may collect 1.6 107ψ(2S) events.

and BESIII 2 109 ψ(2S) events/year.

• Hadronic decays, systematic study of decays with better BR measurements, 15% rule, VP, VT and other modes

BR uncertainty 10-30% a few %

• Radiative decays, search for glueballs, etc

• c decays, systematically measure BR

BR uncertainty 10-30% a few %

Upper limits will be improved by two orders

• search

Assuming the Br is the same for and c

with 3 109ψ(2s), fast simulation shows, using 3 2P in

--------------

about 600 signal events can be selected, and there are about

12 background events from corresponding c decays.

• 1P1 search

From ψ(2s) 0 1P1 c 4K

with 3 109ψ(2s), fast simulation shows,

about 250 signal events can be detected, with about 8 background events.

c

c

cS )(2 ,KK0

Signal for (598) background(12)

With 3 109 ψ(2s) produced

c

Signal for 1P1 (248) background(8)

With 3 109 ψ(2s) produced

Charmed Meson Physics

Low background, simple events, using D, Ds tagging,

can have lower systematic errors to study

• Pure leptonic decays. fD , fDs

• Semileptonic decays ,

• Non-leptonic decays

One year run at (3770) or 4.03 GeV, a few percents statistically

• mixing through ( ) ( )Lower statistics compared with B factories

Need careful study to evaluate physics reaches and make

comparison

00 DD

eeKD 0ee

Ds

K K

Decay Input Measured Stat. Stat. Total

Mode Value Value Error Error Error

80 pb-1 80 pb-1

1000 pb-1 PDG

3.7 3.590.15 4.2% 1.2% 2.3%

7.8 8.120.34 4.2% 1.2% 4.1%

7.7 7.800.40 5.1% 1.4% 6.7%

2.8 2.990.17 5.7% 1.6% 9.0%

5.6 5.160.32 6.2% 1.8% 12.8%

0.69 0.750.05 6.7% 1.9% 8.0%

3.4 3.330.17 5.1% 1.4% 4.9%

0.4 0.370.06 16.2% 4.6% 16.2%

7 3 events

90 10 events for 1000 pb-1 (4000 pb-1

/y)

KD 0

KD0

KD

0KD

0KD

KKD

eeKD 0

eeD 0

D

With one side semi-leptonic

decay,

the other tagged D mass di

stribution

τ Physics

Threshold production, without open charm background

one year data taking at 3.57 GeV or 3.67 GeV will produce

about 2-10 million τ events, with small backgrounds

• CP violation in τ decays, with 427 pure leptonic decay e events collected at 4.03 GeV, A a few percent

more events( a factor of ~100) and more decay channels will give better results

• precise τmass and τ neutrino mass measurement

•τ Decay studies

Study Baryonic Excited States (N* , * , * and * ) from J/ψ and ψ(2s) Decays

• Complementary to experiments at CEBAF, GRAAL

and SPRING8

• Can systematically study the excited bayrons

•Can reveal the quark-gluon structure of matter

Re-measure R-values in BEPC Energy Range

The contribution to the (MZ2) from R-value remains t

o be significant. After R values at lower energy get measured accurately, from VEPP-2M in Novosibirsk and factory in Frascati (~1%level), it is worth while making the R measurement in BEPC energy range with an uncertainty of ~3%, should check if 1% level is possible? .

Should try to maintain this possibility in the design of BEPCII.

• Study of QCD and hadron production in BEPC energy region

The Impact of BES’s New R-Values on the SM Fit

Searches and Possible New Physics

• Lepton flavor violating J/ψ decays

J/ψ e, e,

• J/ψ decay to D+X

• CP violation in J/ψ decays

• With more than 109 J/ψand ψ’ events, the upper limits for rare and forbidden decays,

Br measurements can reach the level of 10-6~10-7

At Hadron2001 held in Protvino of Russia,

• Fermilab pbar p experiment admitted that, the signals of

1P1 and are not confirmed, with a factor of 3 more luminosity than before.

• VES stated that the 1-+ signal of 1(1400) found before, should be explained

as the feed down of the nearby peak, for 1(1600) there is still possibility it is

a 1-+ state, but VES played down the significance.

On the other hand, BNL E852 still hold the 1-+ signals are true.

So the situation becomes more uncertain, it gives BES more

chance to make discoveries, but it also tells that the hadron

physics is very complicated.

c

BESIII Detector Overview

According to the current plan, among the detector components, almost every component

Should be replaced with new detector.

The new detector design is very much affected

by using retired L3 BGO crystals as the barrel calorimeter.

Schematic of BESIII detector

Major Upgrades in BESIII

• Superconducting magnet

• Calorimeter: BGO with E/E ~ 2.5 % @ 1GeV

• MDC IV: with small cell, Al wires and He gas

• Vertex detector: Scintillation fibers for trigger

• Time-of-flight : T ~ 65 ps

• Muon detector

• New trigger and DAQ system

• New readout electronics

Scintillating fiber for Trigger

1.27 mm or thinner Be beam pipe may be used

• R ~ 3.5 cm• 2 double-layers: one axis layer and one stereo layer• Scintillating fiber: 0.3*0.3 mm2, L~60 cm• Clear fibers: 0.3*0.3 mm2, L~1.4 m• two side readout by APD (Φ3) (below –300)• Signal/noise: <6 p.e.> / <~1p.e.>•

~ 50 m z ~ 1mm• Total # of channels: 27 x 8 = 216

Main Draft Chamber

• End-plates with stepped shape to provide space for SC quards and reduce background

– Inner part: stepped conical shape, cos θ= 0.93– Outer part: L = 190 cm, cosθ= 0.83 with full tracking volume

• cell size: ~ 1.4 cm x 1.4 cm• Number of layers (cell in R): 36

• Gas: He:C2H6 , or He:C3H8

• Sense wire: 30 m gold-plated W , • Field wire: 110 m gold-plated Al• Single wire resolution : 130 m• Mom. resolution : 0.8 % @ 1GeV &1T, 0.67% @1GeV&1.2T• DE/dx resolution: 7%

Trackerr simulation of MDC,

pt as a function of pt in % for pion, wire resolution 130 m

Trackerr simulation of MDC,

pt as a function of pt in % for pion, wire resolution 100 m

PID: Time of Flight Counters

• Double layers TOF: ( or TOF +CCT) plastic scintillator (BC-404) • 80 pieces per layer in • R: 66 ~ 75 cm, • Thickness 4 cm, length ~ 190 cm • Readout both sides by F-PMT • Time Resolution ~ 65 ps 2σon k/ separation: 1.1~1.5GeV/c (for polar angle 00~ 450) • For CCT option, need R&D

TOF+TOF TOF+CCT

BGO Barrel Calorimeter

To provide minimum space for main draft chamber and TOF and to obtain the necessary solid angle, one must modify L3 BGO crystals, and add new crystals

• 13 X0: E/E ~ 2.5 % @ 1GeV

• Rin ~ 75cm , Lin ~ 200cm cos = 0.83

• Cut L3 BGO crystals (10752) 22 X0 (24cm) into 13X0 (14cm) + 8.5 X0(9.5cm) • Making new bars of 14 cm by gluing 9.5cm + new crystal of 4.5cm • new BGO crystals needed.  

Electromagnetic Calorimetr with BGO(electron)

0. 0

2. 0

4. 0

6. 0

8. 0

10. 0

12. 0

0 0. 5 1 1. 5 2

Energy (GeV)

Res

olut

ion

(%)

L=13X0

L=15X0

Electromagnetic Calorimetr with BGO(photon)

0. 0

2. 0

4. 0

6. 0

8. 0

10. 0

12. 0

14. 0

0 0. 5 1 1. 5 2

Energy (GeV)

Res

olut

ion

(%)

L=13X0

L=15X0

Endcap Detector

Two possible technologies can be used,

1. CsI crystals as in the detector figure, similar technology as in the barrel, need endcap TOF.

2. Similar technique as KLOE using lead-fiber

technique, may not need TOF counters.

The first choice is preferred.

Superconducting Magnet for BESIII

• B: 1 ~ 1.2 T, • L ~ 3.2 m• Rin~ 105 cm, Rout ~ 145 cm Technically quite demanding for IHEP,no experience before, need collaboration from abroad and other institutes in China, both for coil and cryogenic system.

Muon Counter

• Barrel (L ~ 3.6m ) + Endcap: cos ~ 0.9

• Consist of ~ 12 layers stream tube or RPC

• Rin ~ 145cm (yoke thickness ~40cm)

• Iron plate thickness: 2-6 cm counter thickness: ~1.5 cm

• Readout hits on strips ~3cm

• total weight of iron: ~400 tons

0

10

20

30

40

50

60

70

80

90

100

0. 3 0. 5 0. 7 0. 9 1. 1 1. 3

Muon acceptance

Pion contamination

Interaction Region

It is very compact at IR, very close cooperation is needed in the designs of detector and machine components at IR

• Understand the space sharing, the support, vacuum tight

• Understand the backgrounds from machine and how to reduce them,

- Beam loss calculation (masks)

- Synchrotron radiation (masks)

- Heating effect (cooling if necessary)

• Understand the effects of the fringe field from SCQ to the detector performances

Luminosity Monitor

Because the situation at the IR, the luminosity has to either

be located quite far away from the IR (3-5m), or in front of

Machine Q magnet, to be designed carefully.

• Accurate position determination;

• Multiple detection elements at each side to reduce the

variation of luminosity when the beam position shifted

BGO crystals ?

Trigger

Trigger rate estimation (using the same trigger conditions as now)

• Background rate, with 40 times beam current and half of the beam lifetime, the rough estimation for the background is 80 times the current rate (10-15), or 800-1200 Hz, taking 1500 as a design number

• Good event rate When leave room for maximum luminosity to be as calculated, 11033, 200 times as current event rate, to be 1500 Hz

• Cosmic ray background can almost be negligible

Total peak trigger rate can be more than 3000 Hz, additional trigger (software) is needed to reduce the event rate to 2000Hz.

Level 0 and 1 are hardware triggers, latency 2.4s,

Level2 is software filtering using online computing farm

Because fastest detector element TOF need a time window of about 30 ns, the trigger can identify bunch train only, not individual bunch

• Level 0 with TOF signals

• Level 1 with hardware track finding, EMC clustering, total EMC energy, VC tracking or hits, counter hits

Front-end Electronics

Pipeline scheme is required

Requirements

• For the timing measurement

25 ps for TOF, 0.5 ns for MDC

• For charge measurement

1% accuracy for EMC, 2% for MDC and TOF

Total number of electronic channels ~ 76800 (too many muon channels?)

Data Acquisition System

Event builder 3000 Hz 6 K bytes ~ 20 Mb/s

Event filtering

Data storage

Run control

Online event monitor

Slow control

Switch network

Offline Computing and Analyses Software

• Computing, network, data storage, data base, processing management

• Supporting software package, data offline calibration, event reconstruction, event generators, detector simulation

Substantial manpower needed for software

Total CPU 36000 MIPS

Data storage 500 Tbytes/y on tapes, 24 Tbytes/y on disks

Bandwidth for data transfer 100 Mbps

Subsystem BES III BES Ⅱ

Vertex XY (m) = 50 100

MDC

XY (m) = 130 250

P/P (0/0) = 0.8 % 1.7%

dE/dx (0/0) = 7 % 8.5%

BEMC

E/√E(0/0) = 2.5 % 20%

z(cm) = 0.3 cm/√E 3 cm /√E

TOF T (ps) = 65 ps 180 ps

counter 12 layers(?) 3 layers

Magnet 1.0 tesla 0.4 tesla

• Vertex chamber ZHANG Qinjian

• Main drift chamber CHEN Yuanbo

• Time of flight counter HENG Yuekun

•EMC shower counter LU Jungguang

• Luminosity monitor WU Jian (USTC)

• Trigger system LIU Zhenan

• Front-end electronics SHENG Huiyi, ZHAO, Jingwei

• Data Acquisition HE Kanglin

• Computing and software MAO Zepu

Major New Subsystems of BESIII

Detector R&D

• A lot of new detector technology

• R&D for most sub-systems started

• Detector optimization is needed

• Modify the detector design when international collaboration is formed, new ideas are mostly welcome

Cost Estimation

• Detector: ~ 220M Chinese Yuan ( ~ 30 M US$ ) – 2/3 to 3/4 are from Chinese Government– International collaboration and contribution

are needed

Cost estimation of Detector subsystem (Preliminary)

In M RMB (1 USD= 8.3 RMB)

• Beam pipe + vertex chamber 3.0

• MDC 11.0

• TOF 6.0

• Barrel EMC 54.0

• Endcap EMC 20.0

• Barrel Muon detector 4.5

• Endcap Muon detector 2.5

• Super conducting magnet 45.0?

• Luminosity 2.0

• Electronics 63.0?

• Trigger and DAQ 13.0

• Total 224.0

about 1/4 to 1/3 of the detector budget either be contributed other sources

or be staged.

Schedule

• Feasibility Study Report of BEPC II has been submitted to the funding agency .

• Technical Design Report of BEPC II to be submitted by first half of 2002.

• Construction started from Summer of 2002

• BESII detector moved away Summer of 2004, and the BESIII iron yoke started to be assembled, mapping magnet early 2005

• Preliminary date of the machine long shutdown for installation : Spring of 2005

• Tuning of Machine : Beginning of 2006

• BESIII detector moved to beam line, May 2006

• Machine-detector tuning, Machine-detector tuning, test run at end of 2006 test run at end of 2006

Intl. Cooperation on BEPC II / BES III

• Intl. cooperation played key role in design, construction and running of BEPC/BES.

• Intl. cooperation will play key role again in BEPC II / BES III: design, review, key technology, installation, tuning ……

• Participation of foreign groups is mostly welcomed.

BESIII should be an international collaboration,

Establish organization accordingly.

Welcome Chinese universities and research institutions to participate in BESIII project

Design, MC simulation

Sub-detectors R&D and construction

Electronics R&D and manufacture

Online/Offline software

Software package

Reconstructions

Calibration

Physics study

In charge of some sub-system or send people to IHEP

More Home Works• More simulation to study the physics reaches with BESIII. magnet? solid angle coverage ?

• More study about the interplay between detector and machine, especially in IR

• More detector simulation to arrive design optimization

• Each system (detector components, DAQ and electronics) needs R&D, prototypes

• Commissioning machine with detector outside beam line,

radiation issue.

• about Cost and schedule

Cost for EMC, SC magnet and electronics is most crucial;

MDC, EMC and SC magnet (including iron structure) on critical path;

Major issues related with BESIII design

• The radius of crystal calorimeter, affecting performances and cost. Possibility of using CsI crystals as EMC.

• Backgrounds associated with machine operation, the design of interaction regions, vacuum, masks, etc.

Experienced man power big issue

If not enough fund is expected, 2nd option

Competition from CLEOC

Serious challenge from CLEOC project

Design machine and detector to be as advanced as possible,

Complete the BEPCII/BESIII project ASAP

Collaboration between BES and CLEO

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 is started, need a lot of detailed work to finish detector design

• Very interesting and very challenging project

Thanks

Thanks

Design parameters for BTCF and BESIII detector

BTCF BESIII

Charged particles

p/p(GeV/c) 0.4%p 0.4%/ 0.7%p 0.5%/

(x 4 ) 90 % (all ), 95% to 4th 83%(all), 93% to 4th

Photons

E/E(GeV) 1%/ E(GeV) 2% 2.5%/E(GeV)

Angular resolution 2 mm/ E 3 mm/ E Particle ID TOF 50 ps (double TOF) 65 ps (double TOF)

Summary BEPC/BES has well operated with many exciting physics

results since beginning the operation in 1989.

There is a great physical opportunity, and challenge as well, for BEPC /BES which calls precision measurement.

BEPCII is proposed as double ring + micro-b with designed luminosity of 11033 cm-2s-1 at 1.55 GeV.

Major upgrade on BES detector, so called BES III.

The project is technically feasible.

Chinese Government agreed to support BEPC II.

Intl. Participation to BEPC II / BES III is highly welcomed..

If BEPCII can reach the luminosity of 1033, then some of the physics intended for tau-c factory can be realized.

At BTCF feasibility study, the main physics topics studied were,

• J/psi decays, to pin down the spin-parity of some glueball and exotic states, 109 to 1010 events are needed, a luminosity of 5 • 1032 is needed.

• to measure the tau neutrino mass, 1033 luminosity is needed, and the detector should have good mom. resolution and good /K separations, to reach a sensitivity ~ 1 MeV

• to reach 10-4 sensitivity, 1033 luminosity is needed for a year, with very good /K is needed to reduce misidentification background.

• To renfirm 1P1 state, 5 • 1032 is needed for a year.

• To measure decay CP violation, very good mom. resolution of p/p = (0.2-0.4)% 1+p2 and good /K separations are needed, needs a luminosity of 5 • 1032.

For all these topics, good momentum resolution and good particle ID are needed

00 DD

Intl. Review on Feasibility Study of BEPC II (2 – 6 April 2001, Beijing)

Two subcommittees prepared two reports:

- Machine: 2 – 4 April, chaired by Prof. Alex Chao

- Detector: 4 – 6 April, chaired by Prof. M. Davier

Joint meeting on the design of IR 4 April.

Summary by Prof. W.P. Panofsky:

• A large amount of excellent professional work has been accomplished by the IHEP team, leading to the Feasibility Study Report on BEPC II.

Summary by Prof. W.P. Panofsky (cont.)

• There is no basic reason why a luminosity greater than 3 x 1032 or even 1033 cannot be reached in accelerator accommodated in present BEPC tunnel.• Strong preference for the two-ring option. • Intl. participation in BEPC II is highly desirable. An aggressive program promising unique performance in the tau charm region would be helpful in promoting intl. participation. •   Intl. participation in BES III detector would be of great value both in sharing costs and in scientific contributions. A workshop exploring the physics potential of BEPC II and addressing BES III design issues would be highly useful.

• Lead-Scintillating fiber: E/E ~6%E-1/2• Scintillating fibers: 1 mm • Volume ratio of fiber: lead: glue = 50:42:8• Readout both side by F-MPTs ( 1.5”)• Cell size: 4.5cm2/PMT• Direction of scint-fiber: up-down• Readout layers in Z direction: 4

• Rout ~ 90cm, Rin ~ 36cm

• Totalscint-fiber: 500Km• Total channels: 768

Endcape EMC

Cost Estimation

Here very rough estimation is given, better numbers will be obtained after

prototypes are made

Detector subsystem Cost estimation(MRMB)

Vertex chamber (beam pipe) 2.95

Main drift chamber 13.58

Barrel TOF 7.0

Barrel EMC 64.95

Muon 2.7

Luminosity 2.0

Endcap EMC 20.0

FED electronics 74.6 (2000RMB/channel)

DAQ system 15.0

Total cost 202.78

The cost for HEP manpower and offline computing are not included

BESIII is expected to be ready in the year of 2005

BES Entries in PDG 2000BES Entries in PDG 2000Part. Entries Page Citations

τ 2 P320 2 P342

D± 1 P546 1 P554

DS 4 P574 4 P578

ηC 1 P651 1 P653

J/ψ 33 P653-661 10 P661

XC0 13 P661-662 2 P662

XC1 8 P663 2 P663

XC2 12 P664-665 2 P665

ψ’ 12 P666-669 5 P669

Total 86     

Page

Invariant Mass Spectrum of 0 0 from J/ Radiative Decay

2++

input mass 1320 MeV, width 100 MeV

Scan with proper spin-parity distributions

1-+

input mass 1390 MeV, width 390 MeV