Design and construction of a Vertex Chamber and measurement of the average B-Hadron lifetime
Four parameters describe the mixing of the three quark generations in the Standard Model of the weak charged current interaction. These four parameters are experimental inputs to the model. A measurement of the mean lifetime of hadrons containing b-quarks, or B-Hadrons, constrains the magnitudes of two of these parameters. Measurement of the B-Hadron lifetime requires a device that can measure the locations of the stable particles that result from B-Hadron decay. This device must function reliably in an inaccessible location, and survive high radiation levels. We describe the design and construction of such a device, a gaseous drift chamber. Tubes of 6.9 mm diameter, having aluminized mylar walls of 100 ..mu..m thickness are utilized in this Vertex Chamber. It achieves a spatial resolution of 45 ..mu..m, and a resolution in extrapolation to the B-Hadron decay location of 87 ..mu..m. Its inner layer is 4.6 cm from e/sup +/e/sup -/ colliding beams. The Vertex Chamber is situated within the MAC detector at PEP. We have analyzed botht he 94 pb/sup -1/ of integrated luminosity accumulated at ..sqrt..s = 29 GeV with the Vertex Chamber in place as well as the 210 pb/sup -1/ accumulated previously. We require a lepton with large momentum transverse to the event thrust axis to obtain a sample of events enriched in B-Hadron decays. The distribution of signed impact parameters of all tracks in these events is used to measure the B-Hadron flight distance, and hence lifetime. 106 refs., 79 figs., 20 tabs.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 5656142
- Report Number(s):
- SLAC-322; ON: DE88004493
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
B MESONS
LIFETIME
DRIFT CHAMBERS
CONSTRUCTION
DESIGN
DATA PROCESSING
EXPERIMENTAL DATA
HADRONIC PARTICLE DECAY
LEPTONS
MONTE CARLO METHOD
MUON DETECTION
PEP STORAGE RINGS
PERFORMANCE
PRESSURE VESSELS
QUANTUM CHROMODYNAMICS
QUARK MODEL
QUARKS
SCINTILLATION COUNTERS
SHIELDING
SHOWER COUNTERS
SPATIAL RESOLUTION
STANDARD MODEL
TRANSVERSE MOMENTUM
WAVE FUNCTIONS
BOSONS
CHARGED PARTICLE DETECTION
COMPOSITE MODELS
CONTAINERS
DATA
DECAY
DETECTION
ELEMENTARY PARTICLES
FERMIONS
FIELD THEORIES
FUNCTIONS
HADRONS
INFORMATION
LINEAR MOMENTUM
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MESONS
MULTIWIRE PROPORTIONAL CHAMBERS
NUMERICAL DATA
PARTICLE DECAY
PARTICLE MODELS
POSTULATED PARTICLES
PROCESSING
PROPORTIONAL COUNTERS
PSEUDOSCALAR MESONS
QUANTUM FIELD THEORY
RADIATION DETECTION
RADIATION DETECTORS
RESOLUTION
STORAGE RINGS
UNIFIED GAUGE MODELS
440104* - Radiation Instrumentation- High Energy Physics Instrumentation
645102 - High Energy Physics- Particle Interactions & Properties-Experimental- Weak Interactions & Properties