Transcript BABAR Drift Chamber Project Co-System Managers D.B.MacFarlane, McGill University A.J.S.Smith, Princeton University BABAR  &  L.

BABAR Drift Chamber Project
Co-System Managers
D.B.MacFarlane, McGill University
A.J.S.Smith, Princeton University
BABAR  &  L. de Brunhoff
Drift Chamber System
Drift Chamber Structure
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Flat aluminum rear (24 mm) and forward (24+12 mm) endplates
– Forward endplate with thin outer section to minimize material
– Preamplifier and digitizer electronics on rear endplate only
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Load-bearing inner and outer walls to reduce deflections
– Inner wall of 1 mm-beryllium (40% load)
– Segmented outer wall of 2x1.5 mm CF skins on Nomex core (60% load)
BABAR  &  L. de Brunhoff
Drift Chamber System
Drift System Layout
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40-layer small-cell chamber
– Cells are 12x18 mm2 in size
– 7104 drift cells with hexagonal
field wire pattern
– 80 and 120 mm gold-plated
aluminum field wires
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Layers organized into superlayers
with same orientation
– Wire directions for 4 consecutive
layers: axial-u-v-stereo
– Required for fast reduction of
input to Level 1 trigger via
segment finding
– Transition field shaping voltages
to maintain reasonably uniform
performance
BABAR  &  L. de Brunhoff
Drift Chamber System
Drift Cell Characteristics
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Nominal 80:20 helium-isobutane
gas mixture
– Low-mass gases able to achieve
sub-100 mm position resolutions
– Low multiple scattering required
by soft B decay products
– dE/dx performance comparable
to argon-based mixtures
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Small Lorentz angle should lead
to good cell efficiency
– Modest entrance-angle
dependence to STR
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Performance confirmed by
measurements with full-length
prototype
BABAR  &  L. de Brunhoff
Drift Chamber System
Drift Chamber Performance
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Expected mass resolution for B0 +- about 22 MeV/c2
– Nearly uniform over center-of-mass polar angle distribution
BABAR  &  L. de Brunhoff
Drift Chamber System
Drift Chamber Collaboration
About 50 physicists and 25 engineers & technicians
Canada:
University of British Columbia
Carleton University
McGill University
University of Montreal
TRIUMF National Laboratory
University of Victoria
United States:
University of Colorado
Colorado State University
Lawrence Berkeley Laboratory
University of Maryland
Massachusetts Institute of
Technology
BABAR  &  L. de Brunhoff
Princeton University
UC Santa Cruz
Stanford Linear Accelerator Center
Italy:
INFN Padova
INFN Pisa
INFN Rome
France:
Laboratoire d'Annecy-le-Vieux
de Physique des Particules
Drift Chamber System
Project Budget
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Canadian contributions from Natural Sciences & Engineering
Research Council and the TRIUMF National Laboratory
US contributions are funded through Department of Energy
Italian contributions are supported by INFN and include only
materials & supplies, with staff engineering & technical support
French contributions are supported by IN2P3 and include only
materials & supplies, with staff engineering & technical support
Additional $3M for Drift Chamber electronics budget not
included here
BABAR  &  L. de Brunhoff
NSERC & TRIUMF
DOE
INFN
IN2P3
760K
1650K
453K
87K
Total
2950K
Baseline, no
contingency
Drift Chamber System
Institutional Responsibilities
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IPP/TRIUMF: Assembly and stringing, design & fabrication of
assembly fixtures, stringing tooling, QC & tension testing, clean room,
slow controls, aging tests
INFN-Pisa, Padova, Rome: Automation for stringing, outer CF cylinder,
HV & LV power supplies & controls, collaboration on inner cylinder
IN2P3-Annecy: Gas system, monitors & controls, dE/dx studies
Colorado: Service boards, tension measurement
Colorado State: Feedthrough design & procurement, aging tests, wire
replacement techniques
Maryland: Environmental controls
Princeton: Collaboration on endplate design, procurement & QC of
endplates, fabrication of assembly fixtures, wire procurement & testing,
tension magnet
SLAC: Integration, mechanical design center, electronics and support
structures, prototype construction, inner cylinder design and
procurement
BABAR  &  L. de Brunhoff
Drift Chamber System
Drift Chamber Status & Schedule
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Endplates machined & drilled by Brenner Tool & Die; delivered
to TRIUMF January 31
Beryllium inner cylinder from Electrofusion; delivered May 9
Outer cylinder completed & test fitted June 20
Assembly & alignment fixtures available at TRIUMF; chamber
structure completed & aligned May 23
Automated stringing tooling assembled & operational after
extensive development by August 6
Wire orders complete, feedthroughs in production & nearly
complete
Main stringing period August-December 1997 at TRIUMF;
delivery to SLAC in March 1998
Project is on schedule for July 1998
installation into BABAR & on budget
BABAR  &  L. de Brunhoff
Drift Chamber System