448 research outputs found
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VXD3: The SLD vertex detector upgrade based on a 307 Mpixel CCD system
No full textThe SLD Collaboration is building a new CCD vertex detector (VXD3) comprising 96 3.2 Mpixel CCDs of 13 cm{sup 2} each for a total of 307 million pixels. This system is an upgrade of the Pioneering CCD vertex detector VXD2 which has operated in SLD since 1992. The CCDs of VXD3 are mounted on beryllium ladders in three cylinders, providing three space point measurements along each track of about 5 microns resolution in all three coordinates. The design and construction of VXD3 builds on three years of successful performance of VXD2. Significant improvements are achieved with VXD3 in impact parameters resolution (about a factor of two) and acceptance ({approximately}20%) through optimized geometry and reduced material. New readout electronics have been developed for this system. This new vertex detector will be installed in late 1995 for the future runs of SLD
SLAC-PUB-7585 August 13, 1997 A Preliminary Measurement of R b using the Upgrade SLD Vertex Detector
No full textWe report a new measurement of R b using data obtained during the 1996 SLD run. This measurement uses a double tag technique, where the selection of a b hemisphere is based on the reconstructed mass of the B hadron decay vertex. The method utilizes the 3D vertexing capabilities of SLD's new CCD vertex detector and the small and stable SLC beams to obtain a high b tagging efficiency and purity of 47:9% and 97:6%, respectively. We obtain a preliminary result of R b = 0:2101 \Sigma 0:0034 stat: \Sigma 0:0022 syst: \Sigma 0:0003 Rc for 1996 data. With our previous measurement from 1993-95 data, we obtain a combined preliminary 93-96 result of R b = 0:2124 \Sigma 0:0024 stat: \Sigma 0:0017 syst: . Submitted to the International Europhysics Conference on High Energy Physics (HEP97), 19-26 August 1997, Jerusalem, Israel.
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Highlights of SLD physics
No full textThe SLAC polarized electron beam allows the SLD experiment a high-precision measurement of sin{sup 2}{theta}{sub W}{sup eff} using the parity violating cross section asymmetry A{sub LR} at the e{sup +}e{sup {minus}} {yields} Z{sup o} vertex. The SLD also uses the small luminous e{sup +}e{sup {minus}} collision region and CCD vertex detector to tag heavy quark final states for probing the Z{sup o} {yields} q{bar q} vertex. Results are presented on the following selected topics: A{sub LR}, the Z{sup o} {yields} the Z{sup o} {yields} b{bar b} branching fraction R{sub b}, and the parity violating cross section asymmetries A{sub b} and A{sub b} and A{sub c} for the Z{sup o} {yields} b{bar b} and Z{sup o} {yields} b{bar b} and Z{sup o} {yields} c{bar c} final states
Measurement of the B + and B 0 Lifetimes from Semileptonic Decays at SLD ��
No full textThe lifetimes of B + and B 0 mesons have been measured using a sample of 150,000 hadronic Z 0 decays collected by the SLD experiment at the SLC between 1993 and 1995. The analysis identi�es the semileptonic decays of B mesons with high �p; p t � leptons and reconstructs the B meson decay length and charge by vertexing the lepton with a partially reconstructed D meson. This method results in a sample of 634 �584 � charged �neutral � decays with high charge purity. A maximum likelihood �t �nds: �B + =1:60 +0:12 �0:11�stat � � 0:06�syst � ps, �B0 =1:55 +0:13 �0:12�stat � � 0:09�syst � ps, and the ratio �B + =�B0
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Physics at the Z pole with SLD
No full textThe authors review recent results from a wide physics program in polarized e{sup +}e{sup {minus}} interactions at the SLC performed by the SLD experiment. Unique and precise measurements of the electroweak parameters A{sub e}, A{sub b}, A{sub c}, and R{sub b} provide valuable constraints on the Standard Model. The excellent 3-D vertexing capabilities of SLD are further exploited to extract precise B{sup +} and B{sub d}{sup 0} lifetimes, as well as measurements of the time evolution of B{sub d}{sup 0} - ({anti B}{sub d}{sup 0}) mixing. Finally, the unique capabilities of the SLC/SLD are used to test QCD in new ways. The authors present results on general properties of particle production in light, c, and b quark events, as well as the first observation of leading particle production in light-quark hemispheres
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B physics at SLD
No full textThe authors review recent B physics results obtained in polarized e{sup +}e{sup {minus}} interactions at the SLC by the SLD experiment. The excellent 3-D vertexing capabilities of SLD are exploited to extract precise B{sup +} and B{sub d}{sup 0} lifetimes, as well as measurements of the time evolution of B{sub d}{sup 0} - ({anti B}{sub d}{sup 0}) mixing
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SLD liquid argon calorimeter
No full textThe liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z{sup 0} decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z{sup 0} events) is discussed
SLACPUB8195 July 1999 Measurement of A c with charmed mesons at SLD
No full textWe present a direct measurement of the parity-violation parameter A c . The measurement is based on 550k Z decays collected by the SLD detector. The mean electron-beam polarization is jP e j = 73#. The tagging of c-quark events was performed using two methods: The exclusive reconstruction of D , D mesons, and the inclusive P T spectrum of soft-pions ## s # in the decayofD !D s .The results of these two methods are combined to give A c =0:688 # 0:035#stat:# # 0:025#sys:# #preliminary#. Contributed to the International Europhysics Conference on High Energy Physics, July 15-21 1999, Tampere, Finland; Ref 6-474, and to the XIXth International Symposium on Lepton Photon Interactions, August 9-14 1999, Stanford, USA
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Studies of QCD B-physics and jet handedness at SLD
No full textWe present tests of the flavor independence of strong interactions via preliminary measurements of the ratios {alpha}{sub s}/{sub alpha}{sub s}(udsc) and {alpha}{sub s}(uds)/{alpha}{sub s}(bc) using data collected by the SLD experiment at SLAC during the 1992 SLD/SLC run. In addition, we have measured the difference in charged particle multiplicity between Z{sup 0} {yields} b{bar b} and Z{sup 0} {yields} u{bar u}, d{bar d}, s{bar s} events, and find that it supports the prediction of perturbative QCD that the multiplicity difference be independent of center-of-mass energy. We have also made a preliminary study of jet polarization and find, using a charge-signed definition, a small net handedness in our sample of hadronic jets
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Measurement of R{sub b} at SLD
No full textWe report a new measurement of Rb using a double tag technique where the b selection is based on topological reconstruction of the mass of the B-decay vertex. The measurement was performed using a sample of 150k hadronic Zo events collected with the SLD at the SLAC Linear Collider during the years 1993-1995. The method utilizes the 3-D vertexing abilities of the SLD CCD pixel vertex detector and the small stable SLC beams to obtain a high b tagging efficiency of 37% for a purity of 97.2%. The high purity reduces the systematics introduced by charm contamination and correlations with Rc. We obtain a result of Rb = 0.2176 +/- 0.0033stat. +/- 0.0017syst. +/- 0.0008Rc
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