bepcii/besiii
DESCRIPTION
BEPCII/BESIII. Frederick A. Harris University of Hawaii QWG Meeting Sept. 20-22, 2003 Fermilab. Representing:. The Beijing Electron Positron Collider. L ~ ~5 10 30 /cm 2 s at J/ peak E cm ~ 2-5 GeV A unique e + e - machine in the -charm energy region since 1989. - PowerPoint PPT PresentationTRANSCRIPT
1
BEPCII/BESIII Frederick A. HarrisUniversity of Hawaii
QWG MeetingSept. 20-22, 2003Fermilab
Representing:
2
The Beijing Electron Positron ColliderL ~ ~51030 /cm2s at J/ peak Ecm~2-5 GeV
A unique e+e- machine in the -charm energy region since 1989.
3
On Feb. 10, 2003, the Chinese government, the state council, approved officially the BEPCII/BESIII upgrade project
4
BEPC II Storage ringBEPC II Storage ring:: Large angle, double-ring
e
RFRF SR
e
IP
22 m
rad2. 5m8ns
1. 5cm
0.1cm
5
BEPCII Design goalBEPCII Design goal
Energy range 1 – 2 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
6Passed SLAC review in May 2002.
BEPCII BEPCII main parametersmain parametersEnergy E(GeV) 1.89 Energy spread(10-4) σe 5.16
Circumference C(m) 237.53 Emittance εx/εy(nm) 144/2.2
Harmonic number h 396 Momentum compact αp 0.0235
RF frequency frf(MHz) 499.8 β*x /β*
y(m) 1/0.015
RF Voltage Vrf(MV) 1.5 Tunes νx/νy/νz 6.57/7.6/0.034
Energy loss/turn U0(keV) 121 Chromaticities ν’x/ν’
y -11.9/-25.4
Damping time τx/τy/τz(ms) 25/25/12.5 Natural bunch length σz0(cm) 1.3
Total current/beam I(A) 0.91 Crossing angle (mrad) ±11SR Power P(kW) 110 Piwinski angle Φ(rad) 0.435Bunch number Nb 93 Bunch spacing Sb(m) 2.4
Bunch current Ib(mA) 9.8 Beam-beam parameter x/ y 0.04/0.04
Particle number Nt 4.5×1012 Luminosity(1033cm-2s-1) L0 1.0
7The BESIII The BESIII DetectorDetector
工
8
Main drift chamber• Inner diameter: 63mm; Outer diameter: 810mm; length: 2400 mm• Inner cylinder: 1 mm Carbon fiber, outer cylinder: 10 mm CF wit
h 8 windows• End flange: 18 mm thick Al 7075 ( 6 steps) • 7000 Signal wires : 25(3% Rhenium) m gold-plated tungsten • 22000 Field wires: 110 m gold-plated Aluminum • Small cell: inner---6*6 mm2, outer--- 8.2 *8.2 mm2,• Gas: He + C3H8 (60/40)• Momentum resolution (@ 1 GeV/c):
• dE/dX resolution: 6-7%.
%37.0%32.0 t
P
Pt
9
85μm
10
EMC: CsI(Tl) crystals• 6300 crystals, (5.2x 5.2 – 6.4 x 6.4) x 28cm3 (15 X0) • PD readout, noise ~1100 ENC• Energy resolution: 2.5%@1GeV • Position resolution: 5mm@1GeV• Tiled angle: theta ~ 1-3o, phi ~ 1.5o
• Minimum materials between crystals
11
no partition wall Mechanical support structure
12
Super-conducting magnet• Al stabilized NbTi/Cu conductor from Hitachi• 1.0 T, <5% non-uniformity• 921 turns, 3150A @4.5K• R = 1.475 m, L=3.52m, cold mass 3.6t• Thickness: 1.92 X0
• Inner-winding methodEsti mati on of the vol tage by quench
0. 050. 0
100. 0150. 0200. 0250. 0300. 0350. 0
1 2 4 8 10 20 30Quench Length (m)
Coil V
olta
ge (m
V)
13
Particle ID: TOF system• 392 pieces BC408, 2.4 m long, 5cm thick • Time resolution 100-110 ps/layer• PMT: Hamamatzu R5942
图 3.8.20 桶部光电倍增管的支撑环,内外两层共 176 个孔。
14
system : RPC• 9 layers, 2000 m2
• Bakelite, no linseed oil • 4cm strips, 10000 channels• Tens of prototypes (up to 1*0.6 m2 )• Noise less than 0.2 Hz/cm2
15
Other systems• Electronics design have been almost finished, several
prototypes have been successfully tested• Trigger system largely based on FPGA technology have been
designed, prototypes underway• DAQ system based on VME/PowerPC and PC farm have
been designed, mini-version setup, software underway• Offline computing environment based on a large scale PC
farm is under study• MC based on GEANT4, first reconstruction framework
released, sub-detector reconstruction code underway
16
Schedule• 5/2004: BESII detector shutdown • 11/2004: supporting structure/york installation• 3/2005: muon chamber installation• 5/2005: magnet installation• 10/2005: magnetic field mapping• 2/2006: EMC installation• 3/2006: MDC/TOF installation• 6/2006: Cosmic-ray run• 9/2006: BESIII detector in place• 12/2006: tuning of detector/machine
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 glueb
alls, hybrids, and exotic states
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, f
D and fDs;; charmed baryons.
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
20
Event statistics at BESIII Physics Channel
Energy (GeV)
Luminosity (1033 cm–2s –1)
Events/year
J/ 3.097 0.6 1.0×1010
3.67 1.0 1.2×107
’ 3.686 1.0 3.0 ×109
D 3.77 1.0 2.5×107
Ds 4.03 0.6 1.0×106
Ds 4.14 0.6 2.0×106
*CLEO took 10 nb D production cross section while we took 5 nb
21
Semi-leptonic decays – one year running
Decay Mode
Input
Br(%)
DetectionEfficiency
Statistics Errors
CKM Elements
D0 K-e+e3.4%
54.6%0.6 % Vcs
D0 K-+ 30.5%
D0 -e+e0.4%
62.2%1.6% Vcd
D0 -+ 44.3%
8.5%6.7%
1.6% Vcs3.7%
0KDe
0eKD
Vcs /Vcs = 1.6%,
Vcd /Vcd = 1.8% Emissing-Pmissing
22
Pure Leptonic decaysDecay Modes
Decay Constant
Branching ratios
Life time
CKM Elements
Precision of decay constants
D+→ fD 2.4% 1.2% 1.8% 3.0%
D+s→
fDs 1.7% 1.8% 0.1% 2.5%
One year of running
23
Absolute Br measurement: clear D tagging
beam energy spread important
One year of running
24
Non-leptonic decaysDecay Mode
Input Br(%)
Detection efficiency
Statistics Error (B/B)
3.7 72.2%~ 0.4%~7.8 34.0%
~12.0 32.0%~7.7 52.0%
~ 0.6%
2.8 12.5%~5.6 9.2%~8.6 7.9%~5.0 22.5%
D+s→ ~3.0 60.0% ~ 1.2%
KD0
KD0
00 KD
KD 0KD
0KD
0KD00KD
One year of running
25
B-Factories CLEO-C BEPCII 400 fb-1 3fb-1 5fb-1
Br(D0→K-+) < 1% <1%Br(D+ →K-+ +) 3-5% <1% <1%Br(D+
s →-+) 5-10% <2% ~ 2%
fD >10 % ~2% ~3%
fDs 6-9% ~2% ~2.5%
Vcs 16% ~1% ~1.5%
Vcd 7% ~1.5% ~2%
Comparison with other facilities
*CLEO took 10 nb D production cross section while we took 5 nb
One year of running
26
DDbar Mixing at BESIII
• DDbar mixing in SM ~ 10 –3 - 10 –10
• DDbar mixing sensitive to “new physics”• Our sensitivity : ~ 10-4
• D0 D0 (K- Acceptance: ~ 40% Background: ~ 10-4
27
QCD and hadron production
• R-value measurement• pQCD and non-pQCD boundary• Measurement of s at low energies• Hadron production at J/’, and continuum • Multiplicity and other topology of hadron event • BEC, correlations, form factors, resonance, etc.
28
R-value measurement
Error on R (5)had (MZ
2)
5.9% 0.02761 ±0.00036 3% 0.02761 ±0.00030 2% 0.02761 ±0.00029
R-value below 2GeV
is important,
via radiative return
29
Errors on R at BESIII Error sources BESII (%) BESIII (%)
Luminosity 2 - 3 1
Detection efficiency 3 - 4 1 - 2
Trigger efficiency 0.5 0.5
Radiative corrections 1 - 2 1Hadron decay model 2 - 3 1 – 2
Statistics 2.5 --
Total 6 – 7 2 - 3
30
Light hadron spectroscopy
• Baryon spectroscopy• Charmonium spectroscopy• Glueball searches• Search for non-qqbar states• Search for 1P1
31
Tau-charm physics after CLEOc?Tau-charm physics after CLEOc?• CLEOc begins running now!• What important physics issues will remain in 2007?• Is the BESIII detector design adequate to address these?• There will be a workshop on these issues in January
2004 in balmy Beijing. Workshop will be a CLEOc/BES joint effort.
• More studies needed before the workshop. • Stay tuned. Will post announcement on the QWG web
page. • Please come.
1.0 T 1.0 T
magnet
----9 layers counter
RichT(ps) = 100-110/layer Double layer TOF
2.0%0.3 cm /E
E/E(0/0) = 2.5 %(1 GeV)z(cm) = 0.5cm/E
EMC6%dE/dx (0/0) = 6 - 7 %
0.5 %P/P (0/0) = 0.5 %(1 GeV) MDC90 mXY (m) = 130CLEOcBES III SubdetectorThe detector of BESIII and CLEOc
33
International collaboration IHEP, Beijing Beijing University , Beijing Tsinghua University , Beijing USTC, Hefei National Central University, Taipei KEK, Tokyo University, Tokyo
Hawaii University, Honolulu
Washington University, Seattle
More collaborators welcomed
34
Summary• The BEPCII/BESIII has been approved officially
by the chinese government• The initial BESIII detector design is finished, prot
otyping is underway, mass production is about to start.
• Rich physics after CLEO-c (upgrade of BEPCII to 3*1033 cm-2s-1 is possible)
• Collaborators are welcomed!