3,812 research outputs found
Characterization of a Single Crystal Diamond Pixel Detector in a High Energy Particle Beam
Diamond has been developed as a material for the detection of charged
particles by ionization. Its radiation hardness makes it an attractive material
for detectors operated in a harsh radiation environment e.g. close to a
particle beam as is the case for beam monitoring and for pixel vertex
detectors. Poly-crystalline chemical vapor deposition (CVD) diamond has been
studied as strip and pixel detectors so far. We report on a first-time
characterization of a single-crystal diamond pixel detector in a 100 GeV
particle beam at CERN. The detectors are made from irregularly shaped single
crystal sensors, 395mm thick, mated by bump bonding to a front-end readout IC
as used in the ATLAS pixel detector with pixel sizes of 50 x 400 mm2. The
diamond sensors show excellent charge collection properties: full collection
over the entire detector volume, clean and narrow signal charge distributions
with a S/N value of >100 and a hit detection efficiency of (99.9 +- 0.1)%. The
measured spatial resolution for particles under normal incidence in the shorter
pixel direction is (8.9 +- 0.1) um.Comment: 11 pages, 9 figure
B Physics at the Tevatron: Run II and Beyond
This report provides a comprehensive overview of the prospects for B physics
at the Tevatron. The work was carried out during a series of workshops starting
in September 1999. There were four working groups: 1) CP Violation, 2) Rare and
Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and
Spectroscopy. The report also includes introductory chapters on theoretical and
experimental tools emphasizing aspects of B physics specific to hadron
colliders, as well as overviews of the CDF, D0, and BTeV detectors, and a
Summary.Comment: 583 pages. Further information on the workshops, including
transparencies, can be found at the workshop's homepage:
http://www-theory.lbl.gov/Brun2/. The report is also available in 2-up
http://www-theory.lbl.gov/Brun2/report/report2.ps.gz or chapter-by-chapter
http://www-theory.lbl.gov/Brun2/report
Diamond detectors for future particle physics experiments
Diamond has recently been shown to be a viable material for detectors in experiments at the next generation of particle accelerators. This contribution surveys the properties of diamond which give it advantages, the results achieved to date, the remaining unresolved issues, and the possible applications for diamond detectors in the future
Observation of Mixing-induced CP Violation in the Neutral B Meson System
This report describes an observation of mixing-induced CP violation and a
measurement of the CP violation parameter, sin(2phi_1), with the Belle detector
at the KEKB asymmetric e+e- collider. Using a data sample of 29.1 fb-1 recorded
on the Upsilon(4S) resonance that contains 31.3 million BBbar pairs, we
reconstruct decays of neutral B mesons to the following CP eigenstates: J/psi
K_S^0, psi(2S) K_S^0, chi_c1 K_S^0, eta_c K_S^0, J/psi K_L^0 and J/psi K^*0.
The flavor of the accompanying B meson is identified by combining information
from primary and secondary leptons, K+/- mesons, lambda baryons, slow and fast
pions. The proper-time interval between the two B meson decays is determined
from the distance between the two decay vertices measured with a silicon vertex
detector. The result sin(2phi_1) = 0.99 +/- 0.14(stat) +/- 0.06(syst) is
obtained by applying a maximum likelihood fit to the 1137 candidate events. We
conclude that there is large CP violation in the neutral B meson system. A zero
value for sin(2phi_1) is ruled out by more than six standard deviations.Comment: 25 pages, 16 figures, accepted for publication in Physical Review
Production of Prompt Charmonia in Annihilation at GeV
The production of prompt , , and is
studied using a data sample collected with the Belle detector at
the and 60 MeV below the resonance. The yield of prompt
mesons in the sample is compatible with that of continuum
production; we set an upper limit at the 95% confidence level, and find pb. The cross-sections for prompt
and direct are measured. The momentum spectrum, production
angle distribution and polarization are studied.Comment: submitted to Phys. Rev. Let
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