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1
BEPCII/BESIII and Physics Goals
Xiaoyan SHEN
For BES Collaboration
QWG4, BNL, USA, June 27-30, 2006
The Beijing Electron Positron Collider (BEPC)
L ~ 5 ×1030 /cm2⋅s at J/ψEbeam~ 1 – 2.5 GeV
BESII Detector
VC: σxy = 100 µm TOF: σT = 180 psMDC: σxy = 220 µm BSC: ∆E/√E= 21 %
σdE/dx= 8.5 % σφ = 7.9 mr∆p/p=1.78√(1+p2) σz = 2.3 cm
µ counter: σrφ= 3 cm B field: 0.4 Tσz = 5.5 cm
Running period: 1997 – 2004
• R scan at 95 energy points in 2-5 GeV region
• 58 million J/ψ data
• 14 million ψ(2S) data
• 33pb-1 data at around 3.77GeV
• off peak data
4
BEPCII: a high luminosity double–ring collider
SC RF
Two rings tunnel
Government approved, and stared construction from end of 2003
5
BEPCII Design goal
Energy range 1 – 2.1 GeV
Optimum energy 1.89 GeV
Luminosity 1 x 10 33 cm-2s-1 @ 1.89 GeV
Injection Full energy injection: 1.55 − 1.89 GeV Positron injection speed > 50 mA/min
Synchrotron mode 250 mA @ 2.5 GeV
Dual purpose machine
May achieve to Ebeam = 2.3 GeV
6
Design Goals and Main ParametersParameters Unit BEPCII BEPC
Operation energy (E) GeV 1.0−2.1 1.0−2.5 Injection energy (Einj) GeV 1.55−1.89 1.3
Circumference (C) m 237.5 240.4 β*-function at IP (βx*/ βy*) cm 100/1.5 120/5
Tunes (νx/νy/νs) 6.57/7.61/0.034 5.8/6.7/0.02 Hor. natural emittance (εx0) mm⋅mr 0.14 @1.89 GeV 0.39 @1.89 GeV Damping time (τx/τy/τe) 25/25/12.5 @1.89 GeV 28/28/[email protected] GeV
RF frequency (frf) MHz 499.8 199.533 RF voltage per ring (Vrf) MV 1.5 0.6−1.6
Number of bunches (Nb) 93 2×1 Bunch spacing m 2.4 240.4
Colliding 910 @1.89 GeV ~2×35 @1.89 GeV Beam current SR
mA 250 @ 2.5GeV 130
Bunch length (cm) σl cm ~1.5 ~5 Impedance |Z/n|0 Ω ~ 0.2 ~4 Crossing angle mrad ±11 0
Vert. beam-beam param. ξy 0.04 0.04 Beam lifetime hrs. 2.7 6−8
[email protected] GeV 1031cm-2s-1 100 1
BEPCII Major Milestones• In 2004, Completed
– Upgrade of Linac;– Moved BES from beam line, and dismounted;– Improve infrastructure, including the power station。
• Resumed synchrotron run,till June, 05.• July. 05 – Sep. 06, 2005:
- Removed everything from ring,tunnel improvement,water pipe and power outlets。finished。
- Install the main ring components,from 2nd of March, 06.
• Sep. 06 – June. 07, ring commissioning, SCQ moved in later. Synchrotron run.
• Aug. 07, BESIII moved to the beam line.• Sep. 07, Commissioning ring and detector together.• Dec. 07 , test run。• Dec. 08, to achieve a lum. of 3×1032cm-2s-1.
8
BEPCII Status•BEPCII linac installation complete(new electron gun; new position source; new rf power (klystrons and modulators); and others.Most design specifications reached at 1st test run.
9
Status of Storage ring• Major magnets; super-conducting RF cavities and
super-conducting quadrupole magnets, beam pipes;
kicker; beam instruments; control system; vacuum
system as well as the cryogenics;
most of the systems have been completed;
• Their installation is under way; ~ 14 magnet sets
• Testing ring in Sep. 2006, without SCQ first;
•Beam collisions expected in spring 2007.
10
Bending magnets Quadrupole magnets
Sextupole magnets Dipole correctors
Magnet System
Started the installation of magnet sets
Cavities delivered and being tested
Super-conducting Quadra-pole
14
BESIII Detector
Be beam pipe
SC magnetMuon Counter
Drift Chamber
CsI(Tl) calorimeter
TOF
15
Magnet: 1 T Super conducting
MDC: small cell & He gasσxy=130 µm
σ p/p = 0.5% @1GeVdE/dx=6%
TOF:σT = 100 ps Barrel
110 ps Endcap
Muon ID: 9 layer RPC
EMCAL: CsI crystal∆E/E = 2.5% @1 GeVσz = 0.6 cm/√E
Trigger: Tracks & ShowersPipelined; Latency = 6.4 µs
Data Acquisition:Event rate = 3 kHzThruput ~ 50 MB/s
BESIII Detector Two rings, 93 bunches: • Luminosity1033 cm−2 s−1 @1.89GeV
6× 1032 cm−2 s−1 @1.55GeV 6× 1032 cm−2 s−1 @ 2.1GeV
The detector is hermetic for neutral and charged particle with excellent resolution , PID adequate, and large coverage.
16
MDCParametersR inner: 63mm ; R outer: 810mm Length (out.): 2582 mm Inner cylinder: 1.2 mm Carbon fiberOuter cylinder: 11.5 mm CF with 8 windowsSense wire : 25 micron gold-plated tungsten (plus 3%Rhenium ) --
- 6796 Layers (Sense wire ): 43
Expected performance
Field wire: 110 micron gold-plated Aluminum --- 21884Gas: He + C3H8 (60/40)Cell: inner chamber --- 6 mm
outer chamber --- 8.1 mm
%6~
@1GeV/C%5.0~
130~
dxdE
P
m
dxdE
P
x
σ
σµσ
17
MDC
18
Wire Stringing Completed
19
Beam test at KEKPrototype tested in a 1T magnetic field
at KEK 12GeV PS last year. Results:• spatial resolution better than 130 µm• cell efficiency over 98%• dE/dX resolution better than 5%
(3σ π/K separation exceeding 700MeV/c).
20
CsI(Tl) crystal calorimeter• Design goals:
– Energy: 2.5% @ 1GeV– Spatial: 0.6cm @ 1GeV
• Crystals:– Barrel: 5280 w: 21564 kg– Endcaps: 960 w: 4051 kg– Total: 6240 w: 25.6 T
21
Testing:•Size•Source tests (137 Cs)•LED tests•PD tests•Preamp tests•Cosmic ray tests•Beam tests (6 x 6 array):
X position
ADC
CsI Calorimeter
22
Mechanical structure
A 1/60 prototype
Status:• Assembly will start soon.
Should be completed by end of year.
• By the end of the year, all FED boards should be tested and installed.
23
TOFCrucial for particle ID• Barrel
– 50mm x 60mm x 2320 mm (inner layer).
– BC408 – 2 layers 88x2
• Endcap– 48 fan shaped pieces –
each end.– BC404
• PMT: Hamamatsu R5942
24
TOF Performance
Time resolution 1-layer (intrinsic):
Beam tests: < 90 psSimulation: < 90 ps
Time resolution of two layers is 100ps to 110psfor kaon and pions.
K/π separation: 2 σseparation up to 0.9 GeV/c.
Capability of K/π separation
25
Beam tests of TOF moduleTOF module includes: scintillator, PMTs, preamps, 18m cable, VME readout board of FEE.
Pion: 104±11ps proton: 70±2ps Electron: 94±3ps
Time resolution from beam test of prototype(including scintillator, PMT, preamp, electronics, cable).Time difference of two TOF layers: no errors from reference time (To) or position.
26
Superconducting MagnetCoil: single layer solenoid Cooling mode: two phase helium force flowSuperconductor: Al stabilized NbTi/CuWinding: inner windingCold mass support: tension rodThermal shield: LN2 shield, MLIFlux return: barrel/end yoke, pole tip
Cryostat
Inner radius 1.375m
Cable dimension 3.7mm*20mm
Electrical parameters
Central field 1.0T
Nominal current 3650A
Stored energy 10MJ
Cold mass 3.6ton
Total Weight 15ton
Inductance 2H
Radiation thickness 2X0
Outer radius 1.7m
Length 3.91m
Coil
Mean radius 1.482m
Length 3.52m
27
BESIII Magnet ProgressThermal insulation assembly
transportation
wiring
installation
Value box tested successfully, will be assembled and plan to start cooling in June 06.
28
Field mappingComputer controlled 3D mapping machine is under development.
Field measuring accuracy < 0.25%.
Measure ~90000 points with 0.5 mm position accuracy.
Mapping device
Status:• Complete cooling test of
the magnet before summer.• Complete the field mapping
together with SCQ before Dec. 31, 2006.
29
Muon Chamber
Barrel + EndCap;
RPC as μ detector;Barrel : 9 layersEndCap: 8 layers
One dimension read-out strips;
30
RPCs
• Extensive testing and long term reliability testing are being done.
31
(RPC module)• Total of 64 endcap modules, 72 barrel modules;• Gas: Ar:C2H2F4:Iso_Butane = 50:42:8• HV voltage: 8000V;• One module contains two RPC layers and one readout layer.
32All RPC production, assembly, testing, and installation completed.
33
Test Result after installation - endcapAverage strip efficiency: 0.97 Spatial resolution: 16.6mm
Mean of 64 endcapRPC = 0.95
34
μ/π Identification
0
10
20
30
40
50
60
70
80
90
100
0.5 0.75 1
Using Muc Info only
%
GeV/c
90.3
6.24
5.59.0
12.618.9
12.0
91.287.6
π fake rate
μ efficiency
Ratio of π decay to μbefore entering Muc
Design Goal
15.09.0 6.0
From Simulation
35
Trigger and DAQ• The trigger design is almost finalized; uses FPGA. • By the end of the year, all the boards should be tested
and installed.• The whole DAQ system tested to 8K Hz for the event
size of 12Kb, a factor of two safety margin.
• The whole DAQ system tested during beam test with MDC and EMC
L1 trigger rate: 4 KHzEvent Size: 12 KBytes
Bandwidth after L1: 48 MByte/sec
Dead time: < 5%
1000 * BESII DAQ system
36
Offline softwareBOSS – BES Offline Software Systembased on Gaudi.
HepEvt McTruthG4Event
HitsDigitsRawDataCnvSvcBES III RawData
Generator EventConverters Simulation
Digitization
ReconstructionAlgorithms
CalibrationAlgorithms RecHits RecTracks
AnalysisTools DstTracks
HistogramsNtuples
RootDstCnvSvcDstData
Rec2DstAlgReconstruction
Calibration &Database
Framework CoreSoftware
Simulaton
Physics AnalysisSoftware
BES III Software
Tremendous amount accomplished so far.Much more to do.
12/01/2006 37
Event Display Tool: BesVis
Based on ROOT, OpenGL, X3D and XML
Support both 2D and 3D view
Operations and controls available through menu and toolbar items
First version was released in December 2005.
38
SIMULATION – Based on Geant4
MDC tracking performance:
Sub-detector Design MCMDC σw (μm) 130 110
σp/p 0.5% 0.4%σdE/dx 6-7% 6%
TOF σt (ps) 90 85EMC σE/E 2.5% 2.2%
σxy(mm) 6 4.8MUC ε(μID) 95% 96%
ε(π->μ) 6% 6.2%
μ- at pt = 1GeV/cMomentum resolutionσ = 0.4 MeV
EMC (barrel) Energy Resolution -single γ
39
Muon Counter TOF
p(GeV/c)0 0.2 0.4 0.6 0.8 1 1.2
β
0.20.30.40.50.60.70.80.9
11.11.2
Ext track
Fired strips
Window
40
BESIII and CLEOc comparison
1.0 T1.0 T magnet
----9 layersµ counter
RichσT(ps) = 100-110/layer Double layer
TOF
2.2%0.5 cm /√E
∆ E/√E(0/0) = 2.5 %(1 GeV)σz(cm) = 0.5cm/√E
EMC
6%σdE/dx (0/0) = 6 - 7 %
0.5 %∆P/P (0/0) = 0.5 %(1 GeV) MDC
90 µmσXY = 130 µm
CLEOcBES IIIDetector
41
Resonance Energy(GeV) Peak Lum.(1033cm-2s-1)
Physics Cross Section (nb)
Nevents/yr
J/ψ 3.097 0.6 3400 10 × 109
τ 3.670 1.0 2.4 12 × 106
DsDs 4.030 0.6 0.32 1.0 × 106
ψ(2S) 3.686 1.0 640 3.2 × 109
D0D0bar 3.770 1.0 3.6 18 × 106
D+D- 3.770 1.0 2.8 14 × 106
DsDs 4.140 0.6 0.67 2.0 × 106
Average Lum: L = 0.5×Peak Lum.; data taking time: T =
Nevent/year = σexp ×L× T
Yearly Event Production
Huge J/ψ and ψ(2S) samples at BESIIIBelow are a few examples of physics reach
Physics Simulations
~3MeV−+→ ππKS
50, 000 ψ˝ Inclusiveevent sample.
~1.2MeV
pπ→Λ
We can learn a lot from CLEOc experience
43
D0 to Kpi1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ ( 0
.000
8 )
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
D0 to Kpi1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ ( 0
.000
8 )
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
A RooPlot of "D0 to Kpi"
D0 to K3pi1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ (
0.00
08 )
0
50
100
150
200
250
300
350
400
450
D0 to K3pi1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ (
0.00
08 )
0
50
100
150
200
250
300
350
400
450
A RooPlot of "D0 to K3pi"
D0 to Kpipi01.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ ( 0
.000
8 )
0
200
400
600
800
1000
1200
1400
1600
D0 to Kpipi01.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ ( 0
.000
8 )
0
200
400
600
800
1000
1200
1400
1600
A RooPlot of "D0 to Kpipi0"
D0 to K0bpipi1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ ( 0
.000
8 )
0
50
100
150
200
250
300
350
400
D0 to K0bpipi1.81 1.82 1.83 1.84 1.85 1.86 1.87 1.88
Eve
nts
/ ( 0
.000
8 )
0
50
100
150
200
250
300
350
400
A RooPlot of "D0 to K0bpipi"
+−→ πKD0 −++−→ πππKD0
+π
00 ππKD +−→−+→ ππKD S
0
50, 000 ψ˝ Inclusive event sample.
σ(mBC) ~ 1.2 MeV/c2
σ(∆E) = 7 MeV
44
BESIII: (8M , M.C.)m(χc1) = 3.508GeV,m(χc2) = 3.553GeV;σ(χc1) = 8.1MeV,σ(χc2) = 9.4MeV.
Ψ' γχcJ , χcJ γJ/ ψ
χc1 χc2
π0
η
Ψ' J/ψ(π0, η), (π0,
χc0m(η) = 549 MeVm(π0) =135 MeV
m(χc-) =3.413GeV,σ(χc0) =9.0MeV.
45
Inv.mass of chrg.trks. (GeV)
Events
χc1χc2
χc0χc1
χc2χc0
χc1χc2
χc0
Ψ' γχcJ , χcJ ππππ Ψ' γχcJ , χcJ ππKK
ηc
BESIII: (0.5 M , M.C.)Ψ' γχcJ, χcJ multi-tracks
Ψ' γχcJ , χcJ (6π)
Ψ' tail
46
Physics Topics at BESIII• Charmonium: J/ψ, ψ(2S), ηC(1S) in J/ψ decay,
χC{0,1,2} , ηC(2S) and hC(1P1) in ψ(2S) decay , ψ(1D) and so on
• Exotics : hybrids, glueballs and other exotics in J/ψand ψ(2S) radiative decays;
• Baryons and excited baryons in J/ψ and ψ(2S) hadronic decays;
• Mesons and mixing of quark and gluon in J/ψ and ψ(2S) decays;
47
• Open charm factory :Absolute BR measurements of D and Ds decays; 1-2%Rare D decay; D0-D0bar mixing;CP violation;f D+, fDs , form factors in semi-leptonic D decays; precise measurement of CKM (Vcd, Vcs);CP violation and strong phase in D Dalitz Decays;light spectroscopy in D0 and D+ Dalitz Decays.• Electromagnetic form factors and QCD cross section; • New Charmonium states above open charm threshold
• R values .; aim at < 3% error• tau physics near the threshold.
48
BESIII Collaboration
Institute of High Energy PhysicsUniversity of Science and
TechnologyPeking UniversityTsinghua UniversityShangdong UniversityNankai UniversityCentral China Normal UniversityUniversity of AnhuiUniversity of ZhejiangUniversity of ZhengzhouNanjing Normal UniversityNanjing UniversityShanxi UniversitySichuan University
University of HawaiiUniversity of WashingtonUniversity of TokyoJoint Institute of
Nuclear Research, Dubna
GSIUniversity of BochumUniversity of Giessen
Henan Normal University
49
Summary• BEPCII linac installation complete.• Elements for collider complete; installation
begins.• BESIII hardware and software progressing
rapidly, although still much to do.• Machine/detector Commissioning expected in
2007.• Rich physics after CLEO-c.• More Collaborators welcomed!
50
Thanks
谢谢
BEPCII/BESIII and Physics GoalsBEPCII: a high luminosity double–ring colliderBEPCII Design goalDesign Goals and Main ParametersBEPCII Major MilestonesBEPCII StatusMagnet SystemBESIII DetectorMDCWire Stringing CompletedBeam test at KEKCsI(Tl) crystal calorimeterMechanical structureTOFTOF PerformanceBeam tests of TOF moduleSuperconducting MagnetBESIII Magnet ProgressField mappingRPCs(RPC module)Test Result after installation - endcapTrigger and DAQOffline softwareEvent Display Tool: BesVisMuon CounterBESIII CollaborationSummary