Linear accelerators

Radio-frequency linear accelerators are used as injectors for synchrotrons and as stand-alone accelerators for the production of intense particle beams, thanks to their ability to accelerate high beam currents at high repetition rates. This lecture introduces their main features, reviewing the different types of accelerating structures used in linacs and presenting the main characteristics of linac beam dynamics. Building on these bases, the architecture of modern proton linear accelerators is presented with a particular emphasis on high-energy and high-beam-power applications.Comment: 25 pages, contribution to the CAS - CERN Accelerator School: Course on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai

Fifty years of the CERN Proton Synchrotron : Volume 2

This report sums up in two volumes the first 50 years of operation of the CERN Proton Synchrotron. After an introduction on the genesis of the machine, and a description of its magnet and powering systems, the first volume focuses on some of the many innovations in accelerator physics and instrumentation that it has pioneered, such as transition crossing, RF gymnastics, extractions, phase space tomography, or transverse emittance measurement by wire scanners. The second volume describes the other machines in the PS complex: the proton linear accelerators, the PS Booster, the LEP pre-injector, the heavy-ion linac and accumulator, and the antiproton rings.Comment: 58 pages, published as CERN Yellow Report https://cds.cern.ch/record/1597087?ln=e

Transverse instability mitigation in hadron synchrotrons using electron lenses

High-intensity beams in ring accelerators are subject to several destabilising effects. Among them are transverse beam instabilities that cause severe beam losses. These instabilities are considered at the design stage of any accelerator. One of the ways to suppress the instability is Landau damping. Landau damping is caused by energy exchange between the incoherent and coherent motion of the beam's particles. In this work, a novel way to provide Landau damping is introduced and studied. A pulsed electron lens produces a betatron tune shift in a hadron bunch as a function of the longitudinal coordinates, which is a longitudinal detuning. An example of transverse detuning is the tune shifts due to octupole magnets. This work considers a pulsed electron lens as a measure to mitigate transverse instabilities. Using a detailed analytical description with the Vlasov formalism, the coherent properties of the longitudinal and transverse detuning are presented. The analytical predictions are compared with the results of the particle tracking simulations. A pulsed electron lens is demonstrated to be a source of tune spread with two components: the static one, leading to Landau damping; and the dynamic one, leading to effective impedance modification, an effect demonstrated analytically and in the particle tracking simulations. The effective impedance modification can be significant for beam stability due to devices with longitudinal detuning, especially for the nonzero head-tail modes. The Vlasov formalism is extended to include the combination of longitudinal and transverse detuning. As a possible application for SIS100 (FAIR at GSI Darmstadt, Germany), a combination of a pulsed electron lens with octupole magnets is considered. Additionally, the results of experiments in the existing ring SIS18 are presented. The feasibility of an electron lens for Landau damping was studied experimentally. It was shown that increasing the current of the electron lens weakens the instability. However, more experiments with a larger range of parameters are necessary to demonstrate the reproducibility of this result. Experiments indicated a potential limiting factor for the usage of electron lenses in SIS18

Concept for a Future Super Proton-Proton Collider

Following the discovery of the Higgs boson at LHC, new large colliders are being studied by the international high-energy community to explore Higgs physics in detail and new physics beyond the Standard Model. In China, a two-stage circular collider project CEPC-SPPC is proposed, with the first stage CEPC (Circular Electron Positron Collier, a so-called Higgs factory) focused on Higgs physics, and the second stage SPPC (Super Proton-Proton Collider) focused on new physics beyond the Standard Model. This paper discusses this second stage.Comment: 34 pages, 8 figures, 5 table

Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jefferson Lab

This report presents a brief summary of the science opportunities and program of a polarized medium energy electron-ion collider at Jefferson Lab and a comprehensive description of the conceptual design of such a collider based on the CEBAF electron accelerator facility.Comment: 160 pages, ~93 figures This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177, DE-AC02-06CH11357, DE-AC05-060R23177, and DESC0005823. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purpose

Particle Physics Reference Library

This third open access volume of the handbook series deals with accelerator physics, design, technology and operations, as well as with beam optics, dynamics and diagnostics. A joint CERN-Springer initiative, the “Particle Physics Reference Library” provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A,B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open acces