556 research outputs found
First Experiments on Stochastic Cooling of Heavy Ion Beams at the ESR
At the experimental storage ring ESR of GSI, one half of the foreseen pick-up and kicker tanks are installed, the rest will follow in 1998. First experimental tests of the stochastic precooling system have been performed since April 1997. Longitudinal Palmer cooling was successfully demonstrated. E-folding cooling times of 8.6 seconds were determined with carbon beams. No significant dependence of the cooling time on the number of particles was observed during these first tests. This may be explained by a low signal to noise ratio of the signals obtained from the pick-ups in the present configuration. With heavy ions in higher charge states faster cooling times are expected. The experiments are an important step towards the realization of experiments with radioactive fragments, e.g. in order to measure nuclear masses or half-lives of stripped exotic ions
Conceptual design of elliptical cavities for intensity and position sensitive beam measurements in storage rings
Position sensitive beam monitors are indispensable for the beam diagnostics
in storage rings. Apart from their applications in the measurements of beam
parameters, they can be used in non-destructive in-ring decay studies of
radioactive ion beams as well as enhancing precision in the isochronous mass
measurement technique. In this work, we introduce a novel approach based on
cavities with elliptical cross-section, in order to compensate for existing
limitations in ion storage rings. The design is aimed primarily for future
heavy ion storage rings of the FAIR project. The conceptual design is discussed
together with simulation results.Comment: Added definition of Uv and Pdiss in the introduction section. Added
Mode numbering in table 1 and figure 1 for more clarity. Corrected one wrong
figure reference. Other minor typo correction
Investigation of Planar Pick-up and Kicker Electrodes for Stochastic Cooling
The success of stochastic cooling crucially depends on the interaction between the beam and high frequency devices for detection (pick-up electrodes) and deflection (kicker electrodes). This contribution shows the theoretical investigation of a planar electrode to be used for stochastic cooling of secondary particles with a beta of 0.83. The coupling to the beam is realised by a slot line. Transition networks are added to extract the signal. The detailed investigation is performed via a numerical electromagnetic field analysis. The longitudinal kick of the deflectors is calculated as a function of the beam position and scaled to the applied voltage. According to the Panofsky-Wenzel theorem the transverse kick is obtained simultaneously. The electromagnetic properties of the discussed electrode are compared to existing ones as currently in use in the ESR storage ring (GSI, Darmstadt)
Innovative procurement frameworks for energy performance contracting in the UK public sector
Procurement Frameworks for Energy Performance Contracting (PFEPCs) simplify the process of negotiating, developing and implementing Energy Performance Contracts (EPCs) with Energy Service Companies (ESCOs). This paper analyses their role in promoting the implementation of cost-effective energy efficiency measures in the UK public sector. Compared to conventional approaches to procuring goods and services involving detailed specifications, PFEPCs translate the challenge of upgrading, retrofitting and replacing energy related equipment and infrastructures into required outputs through functional specifications. The innovativeness of specific PFEPCs often lies less in the diffusion of ‘developmental’ innovative energy efficient solutions, although partner bidding approaches create favourable conditions for innovation. However increasing standardisation and
bundling prove successful at lowering transaction cost, which enables ESCOs to address projects which would not be considered in the absence of PFEPCs due to high transaction costs. This
particular organisational innovation opens the market up to new approaches to implementing costeffective energy efficiency measures
Temperature Dependence of Facet Ridges in Crystal Surfaces
The equilibrium crystal shape of a body-centered solid-on-solid (BCSOS) model
on a honeycomb lattice is studied numerically. We focus on the facet ridge
endpoints (FRE). These points are equivalent to one dimensional KPZ-type growth
in the exactly soluble square lattice BCSOS model. In our more general context
the transfer matrix is not stochastic at the FRE points, and a more complex
structure develops. We observe ridge lines sticking into the rough phase where
thesurface orientation jumps inside the rounded part of the crystal. Moreover,
the rough-to-faceted edges become first-order with a jump in surface
orientation, between the FRE point and Pokrovsky-Talapov (PT) type critical
endpoints. The latter display anisotropic scaling with exponent instead
of familiar PT value .Comment: 12 pages, 19 figure
Crossover Scaling Functions in One Dimensional Dynamic Growth Models
The crossover from Edwards-Wilkinson () to KPZ () type growth is
studied for the BCSOS model. We calculate the exact numerical values for the
and massgap for using the master equation. We predict
the structure of the crossover scaling function and confirm numerically that
and , with . KPZ type growth is
equivalent to a phase transition in meso-scopic metallic rings where attractive
interactions destroy the persistent current; and to endpoints of facet-ridges
in equilibrium crystal shapes.Comment: 11 pages, TeX, figures upon reques
West Nile Virus Antibody Prevalence in Wild Mammals, Southern Wisconsin
Twenty percent prevalence of West Nile virus antibody was found in free-ranging medium-sized Wisconsin mammals. No significant differences were noted in antibody prevalence with regard to sex, age, month of collection, or species. Our results suggest a similar route of infection in these mammals
Exploring the role of servitization to overcome barriers for innovative energy efficiency technologies – the case of public LED street lighting in German municipalities
In this paper we analyse the case for public application of LED street lighting. Drawing from the energy services literature and transaction cost economics, we compare modes of lighting
governance for modernisation. We argue that servitization can accelerate the commercialisation and diffusion of end-use energy demand reduction (EUED) technologies in the public sector if third party energy service companies (ESCo) overcome technological, institutional and economic barriers that accompany the introduction of such technologies resulting in transaction costs. This can only succeed with a supportive policy framework and an environment conducive towards the dissemination of specific technological and commercial knowledge required for the diffusion process
Commissioning of a continuous broadband data acquisition for Schottky signals in storage ring experiments at GSI and FAIR
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