[en] This paper describes the radiation testing of CCDs for the vertex detector now installed at the SLAC linear collider. In addition to data from the batch qualification, results are also presented on the effect of biasing the CCDs during irradiation. A comparison between Co⁶⁰ and Sr⁹⁰ irradiation is made and initial results for radiation effects in the vertex detector during operation are presented

[en] This paper describes the design, construction, and initial operation of the SLD Vertex Detector, the first device to employ charge coupled devices (CCDS) on a large scale in a high energy physics experiment. The Venex Detector comprises 480 CCDS, with a total of 120 Mpixels. Each pixel functions as an independent particle detecting element, providing space point measurements of charged particle tracks with a typical precision of 5 μm in each coordinate. The CCDs are arranged in four concentric cylinders just outside the beam pipe which surrounds the e⁺e^- collision point of the SLAC Linear Collider (SLC). The Vertex Detector is a powerful tool for distinguishing secondary vertex tracks, produced by decay in flight of heavy flavour hadrons or tau leptons, from tracks produced at the primary event vertex. Because the colliding beam environment imposes severe constraints on the design of such a detector, a six year R ampersand D programme was needed to develop solutions to a number of problems. The requirements include a low-mass structure (to minimize multiple scattering) both for mechanical support and to provide signal paths for the CCDS; operation at low temperature with a high degree of mechanical stability; and relatively high speed CCD readout, signal processing, and data sparsification. The lessons learned through the long R ampersand D period should be useful for the construction of large arrays of CCDs or smart pixel devices in the future, in a number of areas of science and technology

[en] We present direct measurements of the Z⁰ -lepton coupling asymmetry parameters A_e , A_μ , and A_τ , based on a data sample of 12063leptonic Z⁰ decays collected by the SLD detector. The Z bosons are produced in collisions of beams of polarized e^- with unpolarized e⁺ at the SLAC Linear Collider. The couplings are extracted from the measurement of the left-right and forward-backward asymmetries for each lepton species. The results are A_e=0.152±0.012(stat) ±0.001(syst) , A_μ=0.102±0.034±0.002 , and A_τ=0.195±0.034±0.003 . copyright 1997 The American Physical Society

[en] We present a new measurement of the τ neutrino helicity h_ντ and the τ Michel parameters ρ , η , ξ , and the product δξ . The analysis exploits the highly polarized SLC electron beam to extract these quantities directly from a measurement of the τ decay spectra, using the 1993 endash 1995 SLD data sample of 4328 e⁺e^-→Z⁰→τ⁺τ^- events. From the decays τ→πν_τ and τ→ρν_τ we obtain a combined value h_ντ=-0.93±0.10± 0.04 . The leptonic decay channels yield combined values of ρ=0.72±0.09±0.03 , ξ=1.05±0.35±0.04 , and δξ=0.88±0.27±0.04 . copyright 1997 The American Physical Society

[en] We report a new measurement of R_b=Γ_Z⁰→bbarb /Γ_{Z⁰→hadrons} using a double tag technique, where the b hemisphere selection is based on the reconstructed mass of the B hadron decay vertex. The measurement was performed using a sample of 130x10³ hadronic Z⁰ events, collected with the SLD detector at SLC. The method utilizes the 3D vertexing abilities of the CCD pixel vertex detector and the small stable SLC beams to obtain a high b -tagging efficiency and purity. We obtain R_b=0.2142±0.0034(stat) ±0.0015(syst)±0.0002( R_c) . copyright 1998 The American Physical Society

[en] We have measured the differential production cross sections as a function of scaled momentum x_p=2p/E_c.m. of the identified hadron species π⁺, K⁺, K⁰, K^*0, φ, p, Λ⁰, and of the corresponding antihadron species in inclusive hadronic Z⁰ decays, as well as separately for Z⁰ decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the modified leading logarithm approximation with the ansatz of local parton-hadron duality, and the predictions of three fragmentation models. The ratios of production of different hadron species were also measured as a function of x_p and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of x_p in light quark (as opposed to antiquark) jets. Differences are observed at high x_p, providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-x_p fragmentation products. copyright 1999 The American Physical Society

[en] We present an improved comparison of the strong coupling of the gluon to light (q_l=u+d+s), c, and b quarks, determined from multijet rates in flavor-tagged samples of hadronic Z⁰ decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation among primary q_l bar q_l, c bar c, and b bar b final states was made on the basis of the reconstructed mass of long-lived heavy-hadron decay vertices, yielding tags with high purity and low bias against ≥ 3-jet final states. We find: α_s^c/α_s^uds=1.036±0.043(stat)_-0.045^+0.041(syst)_-

[en] We present a direct measurement of the parity-violation parameter A_b using a self-calibrating track-charge technique. In the SLAC Linear Collider Large Detector (SLD) experiment we observe hadronic decays of Z⁰ bosons produced in collisions between longitudinally polarized electrons and unpolarized positrons at the SLAC Linear Collider. A sample of b bar b events is selected using the topologically reconstructed mass of B hadrons. From our 1993 endash 1995 sample of approximately 150000 hadronic Z⁰ decays, we obtain A_b=0.911±0.045(stat) ±0.045(syst) . copyright 1998 The American Physical Society

[en] The lifetimes of B⁺ and B⁰ mesons are measured using a sample of 150000hadronic Z⁰ decays collected by the SLD experiment at the SLAC Linear Collider between 1993 and 1995. Two analyses are presented in which the decay length and charge of the B meson are reconstructed. The first method uses a novel topological vertexing technique while the second uses semi-inclusively reconstructed semileptonic decays. The topological analysis yields a sample of 6033 (3665) charged (neutral) vertices with good charge purity, whereas the semileptonic analysis yields a smaller sample of 634 (584) charged (neutral) decays with excellent charge purity. Combining the results from both analyses, we find τ_B⁺=1.66±0.06(stat )±0.05(syst) ps, τ_B⁰=1.64±0.08(stat )±0.08(syst) ps, and τ_B⁺/τ_B⁰ =1.01±0.07(stat)±0.06( syst) . copyright 1997 The American Physical Society