Transcript ICHEP2002 - Istituto Nazionale di Fisica Nucleare

DØ at Run IIa
as the new
B-Physics/charmonium player
Heriberto Castilla
Cinvestav-IPN
Dzero Collaboration
Workshop on Quarkonium
November 8-10, 2002 at CERN
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Physics Challenges  The Upgraded Tevatron
Physics goals for Run 2
 precision studies of weak bosons, top, QCD, B-physics
 searches for Higgs, supersymmetry, extra dimensions, other new
phenomena
require
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


electron, muon, and tau identification
jets and missing transverse energy
flavor tagging through displaced vertices and leptons
luminosity, luminosity, luminosity…
Run 1b
Run 2a
Run 2b
66
36  36
140 103
1.8
1.96
1.96
1.6 1030
8.6 1031
5.2 1032
 Ldt (pb-1/week)
3.2
17.3
105
Bunch xing (ns)
3500
396
132
2.5
2.3
4.8
Bunches in Turn
s (TeV)
Typical L (cm-2s-1)
Interactions / xing
Peak Lum. achieved over 3.5 1031 cm2s1
Run 1  Run 2a  Run 2b
Planned to reach Run 2a design
-1
-1
-1
0.1 fb  24 fb  15 fb
by Spring 2003
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Tevatron Luminosity
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
The Run II DØ Detector
Calorimeters
Tracker
Muon
System
antiprotons
protons
Beamline
Shielding
20 m
Electronics
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
DØ in RunII
• Center of Mass Energy = 1.96 TeV
• Expect
2 fb-1 by end of 2004 (RunIIa),
15 fb-1 by 2008 (RunIIb)
• Goals
–
–
–
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B Physics ( B lifetime, B mixing, exclusive decays)
J/ and  production properties (polarization vs pT)
Comprehensive study of top quark properties
Precise measurements of mtop, mW
Search for new phenomena (SUSY, technicolor,…)
Search for the Higgs boson
QCD (proton structure, quark compositeness)
• DØ’s strength is high-pT Physics but we can also do lowpT Physics
• Requires
– Measurement of leptons (e, ), jets, missing pT
– Flavor tagging of jets
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
DØ Tracker
125 cm
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Silicon Microstrip Tracker (SMT)
12 F Disks
4 H Disks
6 Barrels
4-layer barrel cross-section
Barrels
F-Disks
H-Disks
sngl + dbl
double
single
Stereo
0, 2, 90
+/-15
+/-7.5
Channels
387072
258048
147456
Modules
432
144
96
Inner R
2.7 cm
2.6 cm
9.5 cm
10.5 cm
Heriberto
Castilla
26 cm
Outer
Rat CERN
9.4
Workshop on Quarkonium, November
8-10, 2002
cm
Tracking Performance
• pT dependent impact parameter
resolution at vertex is 100 m
using SMT only tracks and
improves to  48 m when CFT
data is combined with SMT data-and is expected to improve further
as studies progress
y
Ks +-
Workshop on Quarkonium, November 8-10, 2002 at CERN
track
x
Heriberto Castilla
Muon System
Forward
Trigger
Scintillators
• Central and Forward regions, coverage up to  = ± 2
PDTs
A- Scint
• Three layers: one inside (A), two outside (B, C) the
toroid magnets
• Consists of scintillators and drift tubes
• Central Proportional Drift Tubes (PDT’s)
Shielding
• 6624 drift cells (10.1  5.5 cm) in 94 three- and
four-deck chambers
• Central Scintillation Counters
• 360 “cosmic ray” counters outside the toroid ( =
22.5)
• 630 “A” counters inside ( = 4.5),  = 0.1
Forward
Tracker (MDTs)
Bottom B/C Scintillators
Fully commissioned
• Forward Mini Drift Tubes (MDT’s)
• 6080 8-cell tubes in 8 octants per layer on North
and South side, cell cross-section 9.4  9.4 mm
• Forward Scintillation Counters (Pixels)
• 4214 counters on the North and South side
•  = 4.5 matches the MDT sector size
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Muon System
Muon Trigger Counters
DØ Detector in Collision Hall, January 2001
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Muon System Performance
Muon Timing
’s from Collisions
Cosmic rays
Timing cuts reduce cosmic bckg., could
aid in detection of slow moving particles
J/ invariant mass
Muon stand alone system
Matching of central tracks to ’s
improves momentum resolution
Muon plus central tracking
M = 3.08  0.04 GeV
 = 0.78  0.08 GeV
on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
CHEP02 – Workshop
31st International
Conference on High Energy Physics, Amsterdam, 24 – 31
July, 2002
DØ Trigger System
Decision times:
~4.2 s
2.3 (7.5) MHz
~100 s
~50 ms
L3 Trigger
1 kHz
5 kHz
50 Hz
Level 1
Level 2
• Subdetectors
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• Towers, tracks, clusters,•
ET
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• Some correlations
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• Pipelined
Level 3
Correlations
• Simple
Reconstruction
Calibrated Data
• Physics
Separated vertex
Algorithms
Physics Objects e, ,
j, , ET
L3/DAQ
Tape
• Entire Trigger Menu configurable and
downloadable at Run start
• Trigger Meisters provide trigger lists for the
experiment by collecting trigger requests from
all physics groups in the Trigger Board
• All past and present trigger lists are stored and
maintained in the dedicated trigger database
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
DØ Beauty/Charmonium Physics Program

J/ψ cross section and polarization
Y cross section
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B Lifetimes
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Average B lifetime: b J/X
b lifetime: bJ/0
B0s lifetime and width: B0sJ/
CP violation, sin(2): B0J/ K0s
B0s mixing: BsDs l X, BsDs(n)
Rare decays, cross sections
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Run II J/ production cross section
4.8 pb-1 of data
~30% systematic
uncertainty
region not measured
inCastilla
Run I
Heriberto
Workshop on Quarkonium, November 8-10, 2002 at CERN
Future measurements: J/ polarization
θ = angle(J/ψlab,μJ/ψ)
I(θ) = 3/2/(α+3)
(1+ α cos2 θ)
α = (σT -2σL)/(σT +2σL)
pt(J/ψ) > 10
|η(J/ψ)| < 1.8
pt(μ) > 2
η(μ)| < 1.9
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
  +- in DØ
• pT of tracks > 2 GeV
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Average B Hadron Lifetime
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Same sample as B±  J/K±
pT(J/)>4 GeV/c
• 416 ± 30 signal events
• 2184 ± 47 prompt J/’s
• (B) = 492 ± 37 m (PDG:
(B) = 469 m)
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
DØ’s First B Hadron Candidates
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•
~5 pb-1
J/ vertex
– pT(track)>2 GeV/c,
matched to a muon
– Positive decay length
• pT(K)>0.5 GeV/c
• B vertex
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–
–
–
pT(B)>10 GeV/c
2<10
Decay length>120 m
Colinearity angle
(pl)>0.9
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla
Conclusion
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First physics results at 1.96 TeV
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Tools to work on quarkonium
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J/ studies
J/ cross section (cross checks with Run I measurement)
Average B Lifetime consistent with previous measurements
First observation in D0 of a charged B
Prompt J/ (’) and from Bs
Upsilon
Polarization measurements
 radiative decays
Improvements in store:
– CTT and STT triggers soon
– Increased rate of J/ and  to tape
Workshop on Quarkonium, November 8-10, 2002 at CERN
Heriberto Castilla