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June 2000 Status of BELLE 1
Status of BELLE
Beyond 1034 e+e- Workshop
The Homestead
Glen Arbor, MI
Daniel Marlow
BELLE
Princeton University
June 17, 2000
June 2000 Status of BELLE 2
Initial Physics Goal
3A
Vtd
,
0,1
3A
Vub
3A
Vcb
1
2
3
Our principal physics goal is to test the KM picture of CP violation by measuring the angle (aka ) of the unitarity triangle.
In phase II, we will seek to measure and ( ).
1
2 &3
June 2000 Status of BELLE 3
Existing Constraints
Existing measurements
of mixing and
limit the
allowed region in the
plane.
00BB
ubV
,
F. Parodi et al.
June 2000 Status of BELLE 4
The Measurement
0B
0B
tag
CP
z
0DNeed to:
•Measure momenta
•ID leptons & K’s
•Measure vertices
e e
0K
/J
June 2000 Status of BELLE 5
The Measurement
The time-dependent asymmetry appears mainly as a mean shift in the distribution between events tagged
as decays and
events tagged as
decays.
z
0B0B
June 2000 Status of BELLE 6
The KEK-B Asymmetric Collider
KEK-B is similar to PEP-II in many ways, although there is a (potentially) important difference in the way in which the beams are brought into collision.
ee
ee
June 2000 Status of BELLE 7
Recent Run Snapshot
Snapshot chosen at randomly selected time.
-1-233peak scm 108.1 L
June 2000 Status of BELLE 8
Daily Luminosity Historypb
-1/d
aypb
-1
date
80 pb-1/day
4.5 fb-1 total
June 2000 Status of BELLE 9
The Magnet
June 2000 Status of BELLE 10
About 10 Countries, 50 Institutes, & 300 People
The BELLE Collaboration
June 2000 Status of BELLE 11
The Silicon Vertex Detector (SVD)
Sensors: HPK DS640 (DSSD’s)
Readout: VA1 chip from IDEAS
June 2000 Status of BELLE 12
SVD Performance
CDC/SVD Track Matching:
%97
June 2000 Status of BELLE 13
CDC Performance (Cosmic Rays)
June 2000 Status of BELLE 14
)(GeV/ 2cM
2eff MeV/ 6.4 c
0SK
CDC Performance
June 2000 Status of BELLE 15
Particle ID (dE/dx, ToF, & Aerogel)
0DD K
June 2000 Status of BELLE 16
CsI EM Calorimeter Performance
MeV 50E
tionReconstruc 0
tionReconstruc
June 2000 Status of BELLE 17
Muon Detection
Note that there are no missing hits in the layers of the muon system, except at the sector edges, where there is support structure.
side- tagplus
/ KJB
June 2000 Status of BELLE 18
0LK Detection
LKP
missP
hi
iS PPP,
4miss
June 2000 Status of BELLE 19
Inclusive Electron Spectrum
cpe GeV/ *
June 2000 Status of BELLE 20
Beam Constrained MassD
June 2000 Status of BELLE 21
D0 Mass Plot
1.80 1.84 1.86 1.90
)(GeV/ 2cMK
To warm up our analysis machinery, we have studied charm lifetimes.
June 2000 Status of BELLE 22
D0 Lifetime
1000 3000-1000-3000
(fs) propert1000 3000-1000-3000
(fs) propert
June 2000 Status of BELLE 23
DS Lifetimes
June 2000 Status of BELLE 24
Dilepton Mass Spectra
June 2000 Status of BELLE 25
Exclusive Mode Reconstruction
KJB /
)(GeV/ 2bc cM
(GeV) E
June 2000 Status of BELLE 26
Exclusive Mode Reconstruction
00 / SKJB
(GeV) E
)(GeV/ 2bc cM
June 2000 Status of BELLE 27
Exclusive Mode Reconstruction
00 / LKJB
)(GeV/ * cpB
MC: histogram
Data: points
June 2000 Status of BELLE 28
Reconstruction
The mode represents a background to the more interesting Cabbibo suppressed mode
0DB
0DB
KDB 0
June 2000 Status of BELLE 29
Reconstruction KDB 0
Particle ID is an effective tool in pulling the signal out from underneath the background.
0DB
KDB 0
(GeV) E
Kao
n pr
obab
ilit
y
KDB 0
June 2000 Status of BELLE 30
Reconstruction KDB 0
Particle ID is an effective tool in pulling the signal out from underneath the background.
0DB
KDB 0
June 2000 Status of BELLE 31
Neutral B Mixing
June 2000 Status of BELLE 32
B Mixing
June 2000 Status of BELLE 33
Summary and Conclusions
• BELLE has accumulated 4.5 fb-1of luminosity in its first ~year of operation.
• The detector is working well and the analysis machinery is beginning to produce results that are competitive with previous measurements.
• One can hope for further increases in luminosity in the months to come.
