Transcript BESIII Physics and Detector Overview International BESIII Workshop Weiguo Li

BESIII Physics and
Detector 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
MDC: xy = 250 m
dE/dx= 8.4 %
BTOF: T = 180 ps (>330 ps)
BSC: E/E= 20 % ,z= 3.0 cm
 counter: z = 5.0 cm
DAQ readout < 10 ms
Major parameters of the BES detector performance
Detector
VC
MDC
BTOF
BSC
Muon
DAQ
Major para.
x,y (m)
xy (m)
p/p (%)
dE/dx(%)
T (ps)
E/E (%)
z (cm)
z (cm)
BESI
200
200-250
1.78 (1+p2)
7.9
375
23.8
4.5
5.0
dead time/event (ms) 20
BESII from 1996
BESII
100
~220
1.7 (1+p2)
8.4
180
20.3
3.0
5.0
<10
Data Collected with BESI and BESII
Ecm
(GeV)
Physics
BES Data
Other Lab.
Data
3.10
J/
7.8106
8.6106
3.69
(2S)
3.9106
1.8106
4.03

1.0105
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
3.1
J/
5107
2, MarkI
Crystal Ball
Pluto……
World J/ and (2S) Sample (106)
J/
(2S)
4
50
45
40
35
30
25
20
15
10
5
0
3.5
3
2.5
2
1.5
1
0.5
0
MarkIII
DM2
BESI
BESII
MARKI MarkII MarkIII Crystal BESI
Ball
Korea (3)
USA (4)
University of Hawaii
University of Texas at Dallas
Colorado State University
Stanford Linear Accelerator
Center
UK (1)
Queen Mary University
Korea University
Seoul National University
Chonbuk National University
Japan (4)
China (15)
IHEP of CAS
Univ. of Sci. and Tech. of China
Shandong 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.
Nikow University
Tokyo Institute of Technology
Miyazaki University
KEK
BES Entries in PDG 2000
Particle
entries
(1440)
3
f2’(1525)
2
f0(1710)
7
2(1870)
2
f2(1950)
2
fJ(2220)
11

2
D
2
Ds
5
c(1S)
1
J/(1S)
33
c0(1P)
13
c1(1P)
8
c2(1P)
12
(2S)
12
(3836)
1
Total
116
Citations of BES Papers
Topics
Citations
BES detector
42
τ
170
J/ψ
82
ψ’(хc)
146
D、DS
51
R
6
Total
492
High Lights of BES Physics Results
 0.20
2
•Precise τ mass measurement 1776.96 00..18
MeV/c
19 0.16
•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;
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)+-) = 2.710.43 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
Scan of (2S) peak
24 energy points between 3.67 and 3.71 GeV
Int. L = 760 nb-1
Improve the
parameters of
(2S)
, B(h), B(+ -),
B(+-J/)
B(+-X)
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
property, Lorenz structure of charged current, CP
violation 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
From BESII to BESIII
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.
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
’’
7.0106
2.3107
D+
’’
5.0106
1.7107
DS
4.14GeV
2.0106
0.72107
 + -
3.57GeV
3.67GeV
0.6106
2.9106
0.2107
0.96107
J/
1.6109
6109
’
0.6109
2109
J/ψ Physics
1. Glueball search
criteria for glueballs:
• no place in qq nonet
• enhanced production in gluon rich processes
• decay patters incompatible with qq states
• reduced   couplings
• masses, quantum numbers consist with lattice QCD
Candidates for glueballs:
f0(1500), fj(1710), (2230) , etc.,
Red ordinary q q
Green interesting
non- q q states
Black other states
not fitting in q q
Lattice QCD Numerical Calculation of Glueball Masses
0++
IBM
1740  71 MeV (1994)  1632  49
UKQCD
1568  89 MeV (1993)  1611  30  160 MeV (1998)
MeV (1998)
improved 1600  100 MeV (1997)  1730  50  80 MeV (1999)
1757  100  86 MeV (2001)
IHEP(Wu)
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 3
J/ψ  x,
x (1300) or a1(1260) or KK1(1400)
with (1300) and a1(1260) decay to  
3. Other interesting topics
Nature of f0(980)
Searching for glueballs and hybrids throughψ(2s)   c
Searching for 1-+ state
producing J/ψ 
x, x  0,
X are mixing of
f0(980), a2(1320),
(1390), (2300),
here (1390) is 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
•  c search
Assuming the Br is the same for  c and c
with 3 109ψ(2s), fast simulation shows, using 3 2P in
 (2 S )   c   0 K  K  -------------,   
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.
Signal for
 c (598)
background(12)
With 3 109 ψ(2s) produced
Signal for 1P1 (248)
With 3 109 ψ(2s) produced
background(8)
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 D 0  K  e  e ,
• Non-leptonic decays
 e e


Ds    
One year run at (3770) or 4.03 GeV, a few percents statistically
• D 0  D 0 mixing through ( K    ) ( K    )
Lower statistics compared with B factories
Need careful study to evaluate physics reaches and make
comparison
Decay
Mode
Input Measured
Value Value
80 pb-1
Stat.
Error
Stat.
Error
80 pb-1
1000 pb-1
Total
Error
PDG
D 0  K  
3.7
3.590.15
4.2%
1.2%
2.3%
D 0  K      
7.8
8.120.34
4.2%
1.2%
4.1%
D   K    
7.7
7.800.40
5.1%
1.4%
6.7%
D   K 0 
2.8
2.990.17
5.7%
1.6%
9.0%
5.6
5.160.32
6.2%
1.8%
12.8%
0.69 0.750.05
6.7%
1.9%
8.0%
D 0  K  e  e
3.4
3.330.17
5.1%
1.4%
4.9%
D 0    e  e
0.4
0.370.06 16.2%
4.6%
16.2%
D   K 0     
D   K  K  
D     
7  3 events
90 10 events for 1000 pb-1 (4000 pb-1 /y)
With one side
semi-leptonic
decay,
the other
tagged D
mass
distribution
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
to 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
1P
1
and  c 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.
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)
Resolution (%)
12.0
10.0
L=13X0
L=15X0
8.0
6.0
4.0
2.0
0.0
0
0.5
1
Energy (GeV)
1.5
2
Electromagnetic Calorimetr with BGO
(photon)
Resolution (%)
14.0
12.0
10.0
L=13X0
L=15X0
8.0
6.0
4.0
2.0
0.0
0
0.5
1
Energy (GeV)
1.5
2
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
100
90
Muon acceptance
80
70

60

50



40
30

20
Pion contamination
10
0
0.3
0.5
0.7
0.9
1.1
1.3
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, 11033, 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 2.4s,
• Level 0 with TOF signals
• Level 1 with hardware track finding, EMC clustering,
total EMC energy, VC tracking or hits,  counter hits
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
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
Switch network
Event filtering
Data storage
Run control
Online event monitor
Slow control
Offline Computing and Analyses Software
• Computing, network, data storage, data base,
processing management
Total CPU 36000 MIPS
Data storage 500 Tbytes/y on tapes, 24 Tbytes/y on disks
Bandwidth for data transfer 100 Mbps
• Supporting software package, data offline
calibration, event reconstruction, event generators,
detector simulation
Substantial manpower needed for software
Subsystem
Vertex
MDC
BES III
BES Ⅱ
XY (m) = 50
100
XY (m) = 130
250
P/P (0/0) = 0.8 %
dE/dx (0/0) = 7 %
E/√E(0/0) = 2.5 %
1.7%
8.5%
20%
BEMC
z(cm) = 0.3 cm/√E
TOF
T (ps) = 65 ps
counter
12 layers(?)
Magnet
1.0 tesla
3 cm /√E
180 ps
3 layers
0.4 tesla
Major New Subsystems of BESIII
• 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
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, 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
Charged particles
p/p(GeV/c)
0.4%p  0.4%/
 (x 4 )
90 % (all ), 95% to 4th
Photons
E/E(GeV)
1%/ E(GeV)  2%
Angular resolution 2 mm/ E
Particle ID
TOF
50 ps (double TOF)
BESIII
0.7%p 0.5%/ 
83%(all), 93% to 4th
2.5%/E(GeV)
3 mm/ E
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 11033 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
• D0  D0
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
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.
Endcape EMC
•
•
•
•
•
•
•
•
•
•
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
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 2000
Part.
Entries
Page
Citations
Page
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
Invariant Mass Spectrum of 0 0 from
J/ Radiative Decay
Scan with proper spin-parity distributions
2++
input mass 1320 MeV, width 100 MeV
1-+
input mass 1390 MeV, width 390 MeV