A Semantic Portal for the International Affairs Sector

The Royal Institute Elcano(dagger) (Real Instituto Elcano) in Spain is a prestigious independent political institute whose mission is to comment on the political situation in the world focusing on its relation to Spain. As part of its dissemination strategy it operates a public website. The online content can be accessed by navigating through categories or by a keyword-based, full text search engine. The work described in this paper aims at improving access to the content. We describe an approach, tools and techniques that allow building a semantic portal, where access is based on the meaning of concepts and relations of the International Affairs domain. The approach comprises an automatic ontology-based annotator, a semantic search engine with a natural language inter-face, a web publication tool allowing semantic navigation, and a 3D visualization component. The semantic portal is currently being tested by the Institute

Experimental Observation of Plasma Wakefield Growth Driven by the Seeded Self-Modulation of a Proton Bunch

We measure the effects of transverse wakefields driven by a relativistic proton bunch in plasma with densities of 2.1 x 10(14) and 7.7 x 10(14) electrons/cm(3). We show that these wakefields periodically defocus the proton bunch itself, consistently with the development of the seeded self-modulation process. We show that the defocusing increases both along the bunch and along the plasma by using time resolved and time-integrated measurements of the proton bunch transverse distribution. We evaluate the transverse wakefield amplitudes and show that they exceed their seed value (< 15 MV/m) and reach over 300 MV/m. All these results confirm the development of the seeded self-modulation process, a necessary condition for external injection of low energy and acceleration of electrons to multi-GeV energy levels

Experimental Observation of Proton Bunch Modulation in a Plasma at Varying Plasma Densities

We give direct experimental evidence for the observation of the full transverse self-modulation of a long, relativistic proton bunch propagating through a dense plasma. The bunch exits the plasma with a periodic density modulation resulting from radial wakefield effects. We show that the modulation is seeded by a relativistic ionization front created using an intense laser pulse copropagating with the proton bunch. The modulation extends over the length of the proton bunch following the seed point. By varying the plasma density over one order of magnitude, we show that the modulation frequency scales with the expected dependence on the plasma density, i.e., it is equal to the plasma frequency, as expected from theory

Design and performance of the beam transfer lines for the HIE-ISOLDE Project

Beam design and beam optics studies for the HIE-ISOLDE transfer lines [1] have been carried out in MadX [2], and benchmarked against Trace3D results [3, 4]. Magnet field errors and alignment imperfections leading to deviations from design parameters have been treated explicitly, and the sensitivity of the machine lattice to different individual error sources was studied. As a result, the tolerances for the various error-contributions have been specified for the different equipment systems. The design choices for the expected magnet field and power supply quality, alignment tolerances, instrument resolution and physical aperture were validated. The methodology and results of the studies are presented

Chapter 4: Beamline – main components

The East Area renovation will cover the refurbishment of the East Hall with its beamlines and infrastructures. A re-design of the beamlines is included to improve the magnet situation, the radiation situation, and maintainability in general. Thanks to a cycled powering mode of the magnets instead of a steady state one, considerable energy savings will be possible. Therefore, several magnet families have to be re-designed to be in accordance with the purposes of the project. The new East Area magnet system consists of 12 different designs with a total of 58 magnets among which 15 are bending magnets, 31 are quadrupoles, and 12 are correctors. In the Proton Synchrotron (PS) area (Building 352), the primary area (Building 157), and the line T08 (Building 157), the magnets will be cycled every 2.4 s. This concerns the lines F61, F62, part of F63, and T08. The other lines, T09, T10, and T11, will be cycled with a period of 4.8 s. Cycling the magnets is an important constraint for the construction of the magnetic parts (yokes). In addition, the coils have to be adapted to match the power supply specifications. The magnets have to be laminated to avoid eddy currents and large delays between the magnetic field and the current application. All laminated magnets currently used and needed in the new in the East Area layout will be refurbished, this concerns four families (or 22 units). The new magnets will be manufactured by industry according to CERN’s design. Another constraint is the magnet overall size limitations. As the layout was fixed at the beginning of the project, all new large magnet designs had to have the same length and width as the present ones. This complicates the designs, as laminated yokes need a larger mechanical structure around the yoke to maintain the laminations. The total lengths and widths have been discussed with the integration team and after few iterations a solution was found and the final designs approved

Linac4 design report

Linear accelerator 4 (Linac4) is designed to accelerate negative hydrogen ions for injection into the Proton Synchrotron Booster (PSB). It will become the source of proton beams for the Large Hadron Collider (LHC) after the long shutdown in 2019–2020. Linac4 will accelerate H– ions, consisting of a hydrogen atom with an additional electron, to 160 MeV energy and then inject them into the PSB, which is part of the LHC injection chain. The new accelerator comprises an ion source and four types of accelerating structures. The particles are accelerated first to 3 MeV energy by a Radio-Frequency Quadrupole (RFQ), then to 50 MeV by three Drift Tube Linacs (DTL) tanks, then to 100 MeV by seven Cell-Coupled Drift Tube Linac (CCDTL) modules, and finally to 160 MeV by twelve Pi-Mode Structures (PIMS). A chopper line placed between the RFQ and the first DTL tank modulates the linac beam at the PSB injection frequency. Linac4 includes transfer and measurement lines up to the PSB injection, where the ions are stripped of their two electrons to leave only protons. Linac4 is 76 metres long and located 12 metres below ground. The first low-energy beams were produced in 2013 and after the commissioning of all accelerating structures the milestone energy of 160 MeV was reached in 2016. Linac4 will be connected to the PSB during the long shutdown of 2019–20, after which it will replace the 50 MeV Linac2 as source of protons for the LHC. The Linac4 is a key element in the project to increase the luminosity of the LHC during the next decade

CERN Proton Synchrotron East Area Facility: Upgrades and renovation during Long Shutdown 2

In this document, we present the upgrade of the East Experimental Area facility which took place during the Long Shutdown 2 (2019–2021). This document covers the renovation of the East Hall beamlines and infrastructure according to a new layout with the goal of improving the magnet and radiation situation in general. The performance of the new beamlines will be optimized in terms of maximum momentum and choice of particle type. Thanks to a cycled powering mode of the magnets instead of a steady state one, considerable energy savings will be possible. This report summarizes the various detailed studies completed from 2016 to 2019

AWAKE readiness for the study of the seeded self-modulation of a 400 GeV proton bunch

AWAKE is a proton-driven plasma wakefield acceleration experiment. We show that the experimental setup briefly described here is ready for systematic study of the seeded self-modulation of the 400 GeV proton bunch in the 10 m long rubidium plasma with density adjustable from 1 to 10 x 10(14) cm(-3). We show that the short laser pulse used for ionization of the rubidium vapor propagates all the way along the column, suggesting full ionization of the vapor. We show that ionization occurs along the proton bunch, at the laser time and that the plasma that follows affects the proton bunch