140 research outputs found
The Synthesis Telescope at the Dominion Radio Astrophysical Observatory
We describe an aperture synthesis radio telescope optimized for studies of
the Galactic interstellar medium (ISM), providing the ability to image extended
structures with high angular resolution over wide fields. The telescope
produces images of atomic hydrogen emission using the 21-cm HI spectral line,
and, simultaneously, continuum emission in two bands centred at 1420 MHz and
408 MHz, including linearly polarized emission at 1420 MHz, with synthesized
beams of 1 degree and 3.4 degrees at the respective frequencies.Comment: Accepted for publication by Astronomy and Astrophysics, Supplement
Serie
Class-Selective Drug Detection: Fluorescently-Labeled Calmodulin as the Biorecognition Element for Phenothiazines and Tricyclic Antidepressants
Abiotic Formation of Valine Peptides Under Conditions of High Temperature and High Pressure
Measurement of the electron structure function F2e at LEP energies
The hadronic part of the electron structure function F2e has been measured for the first time, using e+e− data collected by the DELPHI experiment at LEP, at centre-of-mass energies of s=91.2–209.5 GeV . The data analysis is simpler than that of the measurement of the photon structure function. The electron structure function F2e data are compared to predictions of phenomenological models based on the photon structure function. It is shown that the contribution of large target photon virtualities is significant. The data presented can serve as a cross-check of the photon structure function F2γ analyses and help in refining existing parameterisations
Measurement of the B-d(0) oscillation frequency using kaons, leptons and jet charge
A measurement of the mass difference, Delta m(d), be tween the two physical B-d(0) states has been obtained from the analysis of the impact parameter distribution of a lepton emitted at large transverse momentum (p(t)) relative to the jet axis and from the analysis of the flight distance distribution of secondary vertices tagged by either a high p(t) lepton or an identified kaon. In the opposite hemisphere of the event, the charge of the initial quark has been evaluated using a high p(t) lepton, a charged kaon or the mean jet charge, With 1.7 million hadronic Z(0) decays recorded by DELPHI between 1991 and 1993, Delta m(d) is found to be: Delta m(d) = 0.531 (+0.050)(-0.046) (stat.) +/- 0.078 (syst.) ps(-1)
Determination of vertical bar V-cb vertical bar from the semileptonic decay B-0->D*(-)l(+)nu
Semileptonic decays B --> D*(-)l(+)nu X were selected from a sample of 3.1 million hadronic Z decays collected by the DELPHI detector at LEP. A topological search for semileptonic B decays to resonant and non-resonant D*(-)pi(+) states was performed and the ratio of the branching fractions: Br(B --> D*(-)l(+)nu X)/Br(B --> D*(-)l(+)nu X) + Br(B-0 --> D*(-)l(+)nu) = 0.19 +/- 0.10(stat) +/- 0.06(syst) was determined. Taking into account this contribution, the differential decay width of B-0 --> D*(-)l(+)nu was measured as a function of the momentum transfer from the B to the D*(-) in two separate analyses, using exclusive and inclusive methods of D*(-) reconstruction. The distributions were fitted over the full momentum transfer range to extract the product of /V-cb/ times the normalization of the decay form factor F(q(max)(2)): F(q(max)(2))/V-cb/ = (35.4 +/- 1.9(stat) +/- 2.4(syst)) . 10(-3). The value of /V-cb/ was computed using theoretical calculations of F(q(max?2), giving: /V-cb/ = (38.9 +/- 2.0(stat) +/- 2.6(syst) +/- 1.7(theory)) . 10(-3). The total branching fraction Br(B-0 --> D*(-)l(-)nu) was determined to be: Br(B-0 --> D*(-)l(+)nu) = (5.52 +/- 0.17(stat) +/- 0.68(syst))%
Production of Strange B-baryons Decaying Into Xi-/+-l-/+ Pairs At Lep
An excess of events containing, in a jet, a same-sign Xi(-/+) - l(-/+) pair as compared to those with an opposite-sign Xi(-/+) - l(-/+) pair has been observed in an analysis of 1.7 million hadronic Z(o) decays collected by the DELPHI detector at LEP between 1991 and 1993 inclusive. The probability for this signal to come from non B-baryon decays is less than 5 x 10(-4). The measured production fraction corresponds to: P(b --> B - baryon) x BR(B - baryon --> Xi(-) l(-) X) = (5.9 +/- 2.1 +/- 1.0) x 10(-4), per lepton species, averaged for electrons and muons and assuming the two channels have an equal contribution. Semileptonic decays of Lambda(b) baryons can account for less than 10% of these events and the major part of the signal has to originate from Xi(b) semileptonic decays, Using the subsample of these events where the Xi(-/+) trajectory has been measured in the Vertex Detector, the lifetime of B-baryons producing a Xi(-/+) in their semileptonic decay final state is found to be: tau(B - baryon --> Xi(-) l(-) X) = 1.5(-0.4)(+0.7) +/- 0.3 ps
Determination of |V| from the semileptonic decay B --> Dl
Semileptonic decays B \rightarrow D^{*-} \ell^+ \nu X were selected from a sample of 3.1 million hadronic Z decays collected by the DELPHI detector at LEP. A topological search for semileptonic B decays to resonant %(D^{**}) and non-resonant D^{*-} \pi^{+} states was performed and the ratio of the branching fractions: \frac {Br ({\mathrm{B} \rightarrow {\mathrm D}^{*-}} \ell^+ \nu X)} {Br({\mathrm{B} \rightarrow {\mathrm D}^{*-}} \ell^+ \nu X) + Br( {\mathrm{B}^0 \rightarrow \mathrm{D}^{*-}} \ell^+ \nu)} = 0.19 \pm 0.10({\mathrm{stat}}) \pm 0.06({\mathrm{syst}}) was determined. Taking into account this contribution, %DB the differential production fraction of the decay the differential decay width of {\mathrm{B}^{0} \rightarrow \mathrm{D}^{*-}} \ell^+ \nu was measured as a function of the momentum transfer from the B to the D^{*-} in two separate analyses, using exclusive and inclusive methods of D^{*-} reconstruction. The distributions were fitted %DB with a linear function over the full momentum transfer range to extract the product of \mathrm{|V_{cb}|} times the normalization of the decay form factor F(q^2_{max}): F(q^2_{max})\mathrm{|V_{cb}|} = (35.0 \pm 1.9({\mathrm{stat}}) \pm 2.3({\mathrm{syst}}) )~\cdot~10^{-3}. The value of \mathrm|V_{cb}| was computed using theoretical calculations of F(q^2_{max}), giving: {\mathrm{|V_{cb}|}} = (38.5 \pm 2.1({\mathrm{stat}}) \pm 2.5({\mathrm{syst}}) \pm 1.7({\mathrm{theory}}))~\cdot~10^{-3}. The total branching fraction Br(\mathrm{B}^{0} \rightarrow D^{*-} \ell^+ \nu) was determined to be: Br ({\mathrm{B}^0 \rightarrow \mathrm{D}^{*-}} \ell^+ \nu) = (5.47 \pm 0.16({\mathrm{stat}}) \pm 0.67({\mathrm{syst}})) \%
Measurement of the B-s(0) lifetime and study of B-s(0)-(B-s(0))over-bar oscillations using D(s)l events
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