The differential cross section for final state radiation from primary quarks is obtained from a s... more The differential cross section for final state radiation from primary quarks is obtained from a study of isolated energetic photons produced in the reactione +e −→Z 0→hadrons+γ, as measured in the DELPHI detector at the CERN LEP collider. When combined with the measurement of the total hadronic width of theZ 0, the observed rate determines the electroweak coupling constants of up and down type quarks, i.e., $$v_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}}^2 + a_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}}^2 = 1.13 \pm 0.29 and v_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}}^2 + a_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}}^2 = 1.65 \pm 043.$$ No evidence is seen for additional photon production from anomalous decays of theZ 0 or from decays of new particles. This measurement leads to upper limits on the production cross section times branching fraction of (a) the Higgs boson in the reactione +e −→Z 0→H +γ,H→hadrons, (b) an excited quark,q *→q+γ, and (c) the contribution of an anomalous decay of theZ 0 into a photon and hadrons. These limits, all at the 95% confidence level, vary from 3 to 10pb as the mass of the intermediate state (H,q * orZ *) varies from 10 GeV/c2 to 80 GeV/c2.
The protective effects of egg-yolk antibodies obtained from hens immunized with fimbrial antigens... more The protective effects of egg-yolk antibodies obtained from hens immunized with fimbrial antigens from a local strain (Escherichia coli K88+ MB, Manitoba, Canada) of K88+ piliated enterotoxigenic E. coli (ETEC) were evaluated in 3- and 21- day-old piglets in which ETEC diarrhea was induced and also in early-weaned piglets in a commercial farm. The results demonstrated that the E. coli
Nitrous oxide produces behavioral effects, the underlying mechanism of which is not known. In the... more Nitrous oxide produces behavioral effects, the underlying mechanism of which is not known. In the mouse staircase test, exposure to nitrous oxide caused a reduction in rearing activity, an effect similar to that produced by benzodiazepines in this paradigm, when its opioid action on locomotion is blocked by naloxone. In this study, we tested whether effects of nitrous oxide might be mediated by benzodiazepine receptors, using chlordiazepoxide as a control. The abilities of nitrous oxide and chlordiazepoxide to reduce rearing were significantly attenuated in mice pretreated with the benzodiazepine receptor blocker flumazenil or rendered tolerant to benzodiazepines. These findings suggest an involvement of benzodiazepine receptors in mediation of certain behavioral effects of nitrous oxide.
A search for light Higgs bosons was performed using the data sample collected in 1990 by the DELP... more A search for light Higgs bosons was performed using the data sample collected in 1990 by the DELPHI detector at LEP, at centre of mass energies between 88.2 and 94.2 GeV. Using the process e+e−→H 0+Z 0*,Z 0*→ff, it is possible to exclude the existence of the standard model Higgs particle with a mass between 0 and 210 MeV/c2 at the 99% confidence level. Extending this analysis to the minimal supersymmetric standard model restricts the lightest neutral Higgs boson to masses above 28 GeV/c2 irrespective of the value of the mixing angle.
The study of the properties of inclusive production ofD s mesons and of events in which a ϕ and a... more The study of the properties of inclusive production ofD s mesons and of events in which a ϕ and a muon are present in the same jet provides two independent measurements of the probability,f sw, for a heavy quark to hadronize into a strangeB orD meson. The data sample analysed corresponds to 243,000 hadronicZ 0 decays. The combined value of these measurements isf sw=0.19±0.06±0.08. From the flight distance distributions ofD s and of (ϕ-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, two values are obtained for theB s0 meson lifetime. Combining these measurements with a previous result based on the study ofD s-μ events, theB s0 meson lifetime is measured to be: 0.96±0.37 ps.
A diagnostic neutral beam is installed on Alcator C-Mod for CXRS, BES, and MSE diagnostics. The b... more A diagnostic neutral beam is installed on Alcator C-Mod for CXRS, BES, and MSE diagnostics. The beam operates at 50 kV and 5.5 A for pulse lengths of 100 ms with a component mix of 22:30:43:4 (E:E/2:E/3:E/18). The high neutral density outside the last closed flux surface and in the beam duct leads to beam excitation and attenuation which inextricably links the details of beam operation with the measurements, CXRS in particular. Reionization experiments demonstrate the pressure limits of operation and guide duct redesign. The CXRS measurements with He and B spectra benefit from the E/2 and E/3 as well as the main energy component. These CXRS measurements will lead to a better understanding of the dependence on beam excitation in the high midplane neutral density and to a better understanding of CXRS for high density plasmas.
The multiplicity distributions of charged particles in full phase space and in restricted rapidit... more The multiplicity distributions of charged particles in full phase space and in restricted rapidity intervals for events with a fixed number of jets measured by the DELPHI detector are presented. The data are well reproduced by the Lund Parton Shower model and can also be well described by fitted negative binomial distributions. The properties of these distributions in terms of the clan model are discussed. In symmetric 3-jet events the candidate gluon jet is found not to be significantly different in average multiplicity than the mean of the other two jets, thus supporting previous results of the HRS and OPAL experiments. Similar results hold for events generated according to the LUND PS and to the HERWIG models, when the jets are defined by the JADE jet finding algorithm. The method seems to be insensitive for measuring the color charge ratio between gluons and quarks.
A study ofB meson decays intoDl X final states is presented. In these events, neutral and charged... more A study ofB meson decays intoDl X final states is presented. In these events, neutral and chargedD mesons originate predominantly fromB + andB 0 decays, respectively. The dilution of this correlation due toD ** production has been taken into account. From 263 700 hadronicZ 0 decays collected in 1991 with the DELPHI detector at the LEP collider, 92D 0→K -π+, 35D +→K -π+π+ and 61D *0→D 0π+ followed byD 0→K -π+ orD 0→K -π+π+π-, are found with an associated lepton of the same charge as the kaon. From theD 0l - andD *+l -, the probabilityf d that ab quark hadronizes into aB − (or $\bar B^0 $ ) meson is found to be 0.44 ±0.08±0.09, corresponding to a total (B s+Λ b ) hadronization fraction of 0.12 −0.12+0.24. By reconstructing the energy of eachB meson, theb quark fragmentation is directly measured for the first time. The mean value of theB meson energy fraction is: $$\left\langle {X_E (B)} \right\rangle = 0.695 \pm 0.015(stat.) \pm 0.029(syst.)$$ ReconstructingD-lepton vertices, the followingB lifetimes are measured: $$\begin{gathered} \tau (B) = 1.27_{ - 0.18}^{ + 0.22} (stat.) \pm 0.15(syst.)ps, \hfill \\ where\bar B \to D^0 \ell ^ - X, \hfill \\ \tau (B) = 1.18_{ - 0.27}^{ + 0.39} (stat.) \pm 0.15(syst.)ps, \hfill \\ where\bar B \to D^ + \ell ^ - X, \hfill \\ \tau (B) = 1.19_{ - 0.19}^{ + 0.25} (stat.) \pm 0.15(syst.)ps \hfill \\ where\bar B \to D^{* + } \ell ^ - X, \hfill \\ \end{gathered} $$ and an average τ(B)=1.23 −0.13+0.14(stat.)±0.15(syst.) ps is found. Allowing for decays into $D**\ell ^ - \bar v$ , theB + andB 0 lifetimes are: $$\begin{gathered} \tau (B^ + ) = 1.30_{ - 0.29}^{ + 0.33} (stat.) \pm 0.15(syst.\exp .) \hfill \\ \pm 0.05(syst.D**)ps, \hfill \\ \tau (B^0 ) = 1.17_{ - 0.23}^{ + 0.29} (stat.) \pm 0.51(syst.\exp .) \hfill \\ \pm 0.05(syst.D**)ps, \hfill \\ \tau (B^ + )/\tau (B^0 ) = 1.11_{ - 0.39}^{ + 0.51} (stat.) \pm 0.05(syst.\exp .) \hfill \\ \pm 0.10(syst.D**)ps. \hfill \\ \end{gathered} $$
A diagnostic neutral beam (DNB) has been installed on Alcator C-Mod to allow the use of CXRS, BES... more A diagnostic neutral beam (DNB) has been installed on Alcator C-Mod to allow the use of CXRS, BES, MSE, and other beam diagnostics in experiments on turbulence and transport. The beam can be operated at up to 50 kV, 6 A extracted current for 100 ms pulses. It can be modulated at up to 1 kHz and can generate H, D, and He beams. Integration of the beam into C-Mod operations required that a number of issues be addressed: interaction of C-Mod power supplies with DNB supplies which caused the beam to operate at currents below perveance, the flow of neutral gas from the beam into C-Mod which affects both breakdown and current rise, and the impact of the beam on the plasma H/D ratio which affects RF heating efficiency. A model for the beam operation is being developed to assist in optimization of beam performance. Modeling of the beam penetration is being benchmarked against observations of the beam emission. The injection of the beam into neutral gas to determine the size of the beam will be discussed. Use of the beam for CXRS will also be discussed.
The differential cross section for final state radiation from primary quarks is obtained from a s... more The differential cross section for final state radiation from primary quarks is obtained from a study of isolated energetic photons produced in the reactione +e −→Z 0→hadrons+γ, as measured in the DELPHI detector at the CERN LEP collider. When combined with the measurement of the total hadronic width of theZ 0, the observed rate determines the electroweak coupling constants of up and down type quarks, i.e., $$v_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}}^2 + a_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}}^2 = 1.13 \pm 0.29 and v_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}}^2 + a_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern-\nulldelimiterspace} 3}}^2 = 1.65 \pm 043.$$ No evidence is seen for additional photon production from anomalous decays of theZ 0 or from decays of new particles. This measurement leads to upper limits on the production cross section times branching fraction of (a) the Higgs boson in the reactione +e −→Z 0→H +γ,H→hadrons, (b) an excited quark,q *→q+γ, and (c) the contribution of an anomalous decay of theZ 0 into a photon and hadrons. These limits, all at the 95% confidence level, vary from 3 to 10pb as the mass of the intermediate state (H,q * orZ *) varies from 10 GeV/c2 to 80 GeV/c2.
The protective effects of egg-yolk antibodies obtained from hens immunized with fimbrial antigens... more The protective effects of egg-yolk antibodies obtained from hens immunized with fimbrial antigens from a local strain (Escherichia coli K88+ MB, Manitoba, Canada) of K88+ piliated enterotoxigenic E. coli (ETEC) were evaluated in 3- and 21- day-old piglets in which ETEC diarrhea was induced and also in early-weaned piglets in a commercial farm. The results demonstrated that the E. coli
Nitrous oxide produces behavioral effects, the underlying mechanism of which is not known. In the... more Nitrous oxide produces behavioral effects, the underlying mechanism of which is not known. In the mouse staircase test, exposure to nitrous oxide caused a reduction in rearing activity, an effect similar to that produced by benzodiazepines in this paradigm, when its opioid action on locomotion is blocked by naloxone. In this study, we tested whether effects of nitrous oxide might be mediated by benzodiazepine receptors, using chlordiazepoxide as a control. The abilities of nitrous oxide and chlordiazepoxide to reduce rearing were significantly attenuated in mice pretreated with the benzodiazepine receptor blocker flumazenil or rendered tolerant to benzodiazepines. These findings suggest an involvement of benzodiazepine receptors in mediation of certain behavioral effects of nitrous oxide.
A search for light Higgs bosons was performed using the data sample collected in 1990 by the DELP... more A search for light Higgs bosons was performed using the data sample collected in 1990 by the DELPHI detector at LEP, at centre of mass energies between 88.2 and 94.2 GeV. Using the process e+e−→H 0+Z 0*,Z 0*→ff, it is possible to exclude the existence of the standard model Higgs particle with a mass between 0 and 210 MeV/c2 at the 99% confidence level. Extending this analysis to the minimal supersymmetric standard model restricts the lightest neutral Higgs boson to masses above 28 GeV/c2 irrespective of the value of the mixing angle.
The study of the properties of inclusive production ofD s mesons and of events in which a ϕ and a... more The study of the properties of inclusive production ofD s mesons and of events in which a ϕ and a muon are present in the same jet provides two independent measurements of the probability,f sw, for a heavy quark to hadronize into a strangeB orD meson. The data sample analysed corresponds to 243,000 hadronicZ 0 decays. The combined value of these measurements isf sw=0.19±0.06±0.08. From the flight distance distributions ofD s and of (ϕ-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, two values are obtained for theB s0 meson lifetime. Combining these measurements with a previous result based on the study ofD s-μ events, theB s0 meson lifetime is measured to be: 0.96±0.37 ps.
A diagnostic neutral beam is installed on Alcator C-Mod for CXRS, BES, and MSE diagnostics. The b... more A diagnostic neutral beam is installed on Alcator C-Mod for CXRS, BES, and MSE diagnostics. The beam operates at 50 kV and 5.5 A for pulse lengths of 100 ms with a component mix of 22:30:43:4 (E:E/2:E/3:E/18). The high neutral density outside the last closed flux surface and in the beam duct leads to beam excitation and attenuation which inextricably links the details of beam operation with the measurements, CXRS in particular. Reionization experiments demonstrate the pressure limits of operation and guide duct redesign. The CXRS measurements with He and B spectra benefit from the E/2 and E/3 as well as the main energy component. These CXRS measurements will lead to a better understanding of the dependence on beam excitation in the high midplane neutral density and to a better understanding of CXRS for high density plasmas.
The multiplicity distributions of charged particles in full phase space and in restricted rapidit... more The multiplicity distributions of charged particles in full phase space and in restricted rapidity intervals for events with a fixed number of jets measured by the DELPHI detector are presented. The data are well reproduced by the Lund Parton Shower model and can also be well described by fitted negative binomial distributions. The properties of these distributions in terms of the clan model are discussed. In symmetric 3-jet events the candidate gluon jet is found not to be significantly different in average multiplicity than the mean of the other two jets, thus supporting previous results of the HRS and OPAL experiments. Similar results hold for events generated according to the LUND PS and to the HERWIG models, when the jets are defined by the JADE jet finding algorithm. The method seems to be insensitive for measuring the color charge ratio between gluons and quarks.
A study ofB meson decays intoDl X final states is presented. In these events, neutral and charged... more A study ofB meson decays intoDl X final states is presented. In these events, neutral and chargedD mesons originate predominantly fromB + andB 0 decays, respectively. The dilution of this correlation due toD ** production has been taken into account. From 263 700 hadronicZ 0 decays collected in 1991 with the DELPHI detector at the LEP collider, 92D 0→K -π+, 35D +→K -π+π+ and 61D *0→D 0π+ followed byD 0→K -π+ orD 0→K -π+π+π-, are found with an associated lepton of the same charge as the kaon. From theD 0l - andD *+l -, the probabilityf d that ab quark hadronizes into aB − (or $\bar B^0 $ ) meson is found to be 0.44 ±0.08±0.09, corresponding to a total (B s+Λ b ) hadronization fraction of 0.12 −0.12+0.24. By reconstructing the energy of eachB meson, theb quark fragmentation is directly measured for the first time. The mean value of theB meson energy fraction is: $$\left\langle {X_E (B)} \right\rangle = 0.695 \pm 0.015(stat.) \pm 0.029(syst.)$$ ReconstructingD-lepton vertices, the followingB lifetimes are measured: $$\begin{gathered} \tau (B) = 1.27_{ - 0.18}^{ + 0.22} (stat.) \pm 0.15(syst.)ps, \hfill \\ where\bar B \to D^0 \ell ^ - X, \hfill \\ \tau (B) = 1.18_{ - 0.27}^{ + 0.39} (stat.) \pm 0.15(syst.)ps, \hfill \\ where\bar B \to D^ + \ell ^ - X, \hfill \\ \tau (B) = 1.19_{ - 0.19}^{ + 0.25} (stat.) \pm 0.15(syst.)ps \hfill \\ where\bar B \to D^{* + } \ell ^ - X, \hfill \\ \end{gathered} $$ and an average τ(B)=1.23 −0.13+0.14(stat.)±0.15(syst.) ps is found. Allowing for decays into $D**\ell ^ - \bar v$ , theB + andB 0 lifetimes are: $$\begin{gathered} \tau (B^ + ) = 1.30_{ - 0.29}^{ + 0.33} (stat.) \pm 0.15(syst.\exp .) \hfill \\ \pm 0.05(syst.D**)ps, \hfill \\ \tau (B^0 ) = 1.17_{ - 0.23}^{ + 0.29} (stat.) \pm 0.51(syst.\exp .) \hfill \\ \pm 0.05(syst.D**)ps, \hfill \\ \tau (B^ + )/\tau (B^0 ) = 1.11_{ - 0.39}^{ + 0.51} (stat.) \pm 0.05(syst.\exp .) \hfill \\ \pm 0.10(syst.D**)ps. \hfill \\ \end{gathered} $$
A diagnostic neutral beam (DNB) has been installed on Alcator C-Mod to allow the use of CXRS, BES... more A diagnostic neutral beam (DNB) has been installed on Alcator C-Mod to allow the use of CXRS, BES, MSE, and other beam diagnostics in experiments on turbulence and transport. The beam can be operated at up to 50 kV, 6 A extracted current for 100 ms pulses. It can be modulated at up to 1 kHz and can generate H, D, and He beams. Integration of the beam into C-Mod operations required that a number of issues be addressed: interaction of C-Mod power supplies with DNB supplies which caused the beam to operate at currents below perveance, the flow of neutral gas from the beam into C-Mod which affects both breakdown and current rise, and the impact of the beam on the plasma H/D ratio which affects RF heating efficiency. A model for the beam operation is being developed to assist in optimization of beam performance. Modeling of the beam penetration is being benchmarked against observations of the beam emission. The injection of the beam into neutral gas to determine the size of the beam will be discussed. Use of the beam for CXRS will also be discussed.
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Papers by Ronald Zúñiga