575 research outputs found

    Trajectory Correction of the LHC Injection Transfer Lines TI 2 and TI 8

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    The LHC injection transfer lines TI 2 and TI 8 will transport very intense high-energy small-emittance proton beams over considerable distances. The relatively tight aperture requires a precise control of the trajectory. A detailed analysis of the trajectory excursions to be expected in the presence of various imperfections has been carried out. To stay within the given aperture a correction scheme is proposed in which two adjacent short straight sections out of every four are equipped with correctors. For both lines together this scheme requires 110 corrector elements. The maximum deflection per corrector remains below 65Ýmrad. Corrector magnets and power supplies will be recuperated from LEP and adapted to their new function. The beam position monitors will use button-type electrodes which can also be recovered from LEP

    Beam transfer to and Injection into LHC

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    Transfer of 450 GeV protons from SPS to LHC will be carried out through two new beam transfer lines with a length of about 2.8-km per line. One beam will use the existing SPS west extraction in LSS6 from where a new line will lead to the LHC injection near intersection 2. A new fast extraction facility in SPS LSS4 is needed for the other beam line which will lead to LHC intersection 8. Economy considerations have led to the decision to use classical magnets of compact design. A lot of components will be recuperated from closed down installations. The injection systems consist of horizontally deflecting Lambertson type septum magnets and vertically deflecting kickers. A careful control of the trajectory and the preservation of the very small emittance during transfer and injection are of key importance. Construction for the transfer lines will start in 1998 to allow first injection tests in 2003. The report describes the layout and optics design and the required performance of the main components

    Control of near-infrared supercontinuum bandwidth by adjusting pump pulse duration

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    We experimentally and numerically investigated the impact of input pump pulse duration on the near-infrared bandwidth of supercontinuum generation in a photonic crystal fiber. We continuously stretched the temporal duration of the input pump laser (centered at 1030 nm) pulses from 500 fs up to 10 ps, while keeping fixed the pump peak power. We observed that the long-wavelength edge of the supercontinuum spectrum is increased by 200 nm as the pump pulse duration grows from 500 fs to 10 ps. We provide a quantitative fit of the experimental results by means of numerical simulations. Moreover, we have explained the observed spectral broadening enhancement induced by pump pulse energy by developing an approximate yet fully analytical model for soliton energy exchange through a series of collisions in the presence of stimulated Raman scattering

    New high level application software for the control of the SPS-LEP beam transfer lines

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    New high level application software is being developed for the control of the SPS and LEP Transfer Lines. This paper briefly describes the model for the operation of these Transfer Lines, which is largely based on previous experience gained during the development and upgrades of the SPS and LEP control systems. The software system is then presented, followed by a description of the high level applications for the control room operators. Tools and methods used for the design and implementation of the system are mentioned

    McGill wetland model: evaluation of a peatland carbon simulator developed for global assessments

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    We developed the McGill Wetland Model (MWM) based on the general structure of the Peatland Carbon Simulator (PCARS) and the Canadian Terrestrial Ecosystem Model. Three major changes were made to PCARS: (1) the light use efficiency model of photosynthesis was replaced with a biogeochemical description of photosynthesis; (2) the description of autotrophic respiration was changed to be consistent with the formulation of photosynthesis; and (3) the cohort, multilayer soil respiration model was changed to a simple one box peat decomposition model divided into an oxic and anoxic zones by an effective water table, and a one-year residence time litter pool. MWM was then evaluated by comparing its output to the estimates of net ecosystem production (NEP), gross primary production (GPP) and ecosystem respiration (ER) from 8 years of continuous measurements at the Mer Bleue peatland, a raised ombrotrophic bog located in southern Ontario, Canada (index of agreement [dimensionless]: NEP = 0.80, GPP = 0.97, ER = 0.97; systematic RMSE [g C m<sup>−2</sup> d<sup>−1</sup>]: NEP = 0.12, GPP = 0.07, ER = 0.14; unsystematic RMSE: NEP = 0.15, GPP = 0.27, ER = 0.23). Simulated moss NPP approximates what would be expected for a bog peatland, but shrub NPP appears to be underestimated. Sensitivity analysis revealed that the model output did not change greatly due to variations in water table because of offsetting responses in production and respiration, but that even a modest temperature increase could lead to converting the bog from a sink to a source of CO<sub>2</sub>. General weaknesses and further developments of MWM are discussed

    McGill Wetland Model: evaluation of a peatland carbon simulator developed for global assessments

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    International audienceWe developed the McGill Wetland Model (MWM) based on the general structure of the Peatland Carbon Simulator (PCARS) and the Canadian Terrestrial Ecosystem Model. Three major changes were made to PCARS: 1. the light use efficiency model of photosynthesis was replaced with a biogeochemical description of photosynthesis; 2. the description of autotrophic respiration was changed to be consistent with the formulation of photosynthesis; and 3. the cohort, multilayer soil respiration model was changed to a simple one box peat decomposition model divided into an oxic and anoxic zones by an effective water table, and a one-year residence time litter pool. MWM was then evaluated by comparing its output to the estimates of net ecosystem production (NEP), gross primary production (GPP) and ecosystem respiration (ER) from 8 years of continuous measurements at the Mer Bleue peatland, a raised ombrotrophic bog located in southern Ontario, Canada (index of agreement [dimensionless]: NEP=0.80, GPP=0.97, ER=0.97; systematic RMSE [g C m?2 d?1]: NEP=0.12, GPP=0.07, ER=0.14; unsystematic RMSE [g C m?2 d?1]: NEP=0.15, GPP=0.27, ER=0.23). Simulated moss NPP approximates what would be expected for a bog peatland, but shrub NPP appears to be underestimated. Sensitivity analysis revealed that the model output did not change greatly due to variations in water table because of offsetting responses in production and respiration, but that even modest temperature increases could lead to converting the bog from a sink to a source of CO2. General weaknesses and further developments of MWM are discussed

    The cross-fertilization of jurisprudence and the principle of proportionality : process and result from a canadian perspective

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    Modern comparative constitutionalism traces back at least to the practice of some states in the post-World War II era of adopting democratic regimes as well as constitutionally entrenched bills of rights. It has since been fueled by the proliferation of international human rights instruments, which has increased with the end of the Cold War. Significant attention was first paid to comparative constitutional structure, but many states have now reached another stage. As notably witnessed by the works of the Council of Europe and especially those of the Venice Commission in the domain of constitutional justice, the question now is no longer about constitutionalism, including whether rights should be constitutionally protected, as much as it is about constitutional justice: how to effectively implement constitutions. Both on a regional and a global level, mutual inspiration is increasingly drawn from the case-law of peer Courts of other countries and even other continents, which gives rise to a cross-fertilisation phenomenon. One constitutional principle that emerges from, and which is still being forged by, such cross-fertilisation is the principle according to which the limitation of human rights and freedoms must be proportional to states’ objectives, that is, the principle of proportionality. More specifically, our topic is about both the historical process of jurisprudential cross-fertilisation and its functional result as far as the principle of proportionality is concerned. We speak from a Canadian perspective. The aim here is to be able to distinguish between what is common and what is distinctive about the Canadian approach

    Low-lying dipole response in the Relativistic Quasiparticle Time Blocking Approximation and its influence on neutron capture cross sections

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    We have computed dipole strength distributions for nickel and tin isotopes within the Relativistic Quasiparticle Time Blocking approximation (RQTBA). These calculations provide a good description of data, including the neutron-rich tin isotopes 130,132^{130,132}Sn. The resulting dipole strengths have been implemented in Hauser-Feshbach calculations of astrophysical neutron capture rates relevant for r-process nucleosynthesis studies. The RQTBA calculations show the presence of enhanced dipole strength at energies around the neutron threshold for neutron rich nuclei. The computed neutron capture rates are sensitive to the fine structure of the low lying dipole strength, which emphasizes the importance of a reliable knowledge of this excitation mode.Comment: 15 pages, 4 figures, Accepted in Nucl. Phys.

    Drip-line To Drip-line Microscopic Nuclear Level Densities

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