摘要:

Uncontrolled beam loss leads to excessive radioactivation in high‐intensity machines. At the same time, it strongly affects performance of high‐energy accelerators and colliders. For the well controlled beam, the loss is typically associated with the low density halo surrounding beam core. There are many mechanisms which contribute to halo formation. Some of them are more important for linear accelerators while other are more relevant to circular machines. In order to minimize uncontrolled beam loss or improve performance of an accelerator, it is very important to understand what are the sources of halo formation, as well as which of them can have significant contribution for a specific machine of interest. In this paper, we overview various mechanisms of halo formation. We then specifically discuss which effects are expected to be dominant in linear accelerator and which effects dominate in rings, concentrating on high‐intensity machines. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638311

出版商:AIP    

年代:1903

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.1638312

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Operational and accidental beam losses in hadron colliders can have a serious impact on machine and detector performance, resulting in effects ranging from minor to catastrophic. Principles and realization are described for a reliable beam collimation system required to sustain favorable background conditions in the collider detectors, provide quench stability of superconducting magnets, minimize irradiation of accelerator equipment, maintain operational reliability over the life of the machine, and reduce the impact of radiation on personnel and the environment. Based on detailed Monte‐Carlo simulations, such a system has been designed and incorporated in the Tevatron collider. Its performance, comparison to measurements and possible ways to further improve the collimation efficiency are described in detail. Specifics of the collimation systems designed for the SSC, LHC, VLHC, and HERA colliders are discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638313

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

In colliding‐beam storage rings transverse and longitudinal beam halo is generated, or depleted, by the effect of head‐on and long‐range beam‐beam collisions. Measurements from several past and present lepton or hadron colliders are compared with simulations and analytical models, highlighting a few halo‐specific techniques. This overview concludes with an outlook on the future Large Hadron Collider (LHC), where long‐range beam‐beam collisions are the dominant perturbation of particle motion and beam‐beam compensation schemes appear a promising remedy. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638314

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Higher energies and higher intensities are the necessary conditions for the success of future accelerators. Higher energies need stronger external electromagnetic fields to guide, focus, and accelerate charged particles, while higher intensities result in source of intense self‐fields. In both cases, particle motion deviates considerably from a plain linear evolution as described by the classical Hill equation of transverse betatron motion. Particle stability becomes an issue: this problem can be properly tackled using tools from the nonlinear theory of dynamical systems. The concept of dynamic aperture for single‐particle motion will be presented underlying links with the fundamental theorems of classical mechanics, such as KAM and Nekhoroshev theorems. Modern numerical techniques to compute the dynamic aperture will be discussed with special emphasis on accuracy analysis. Finally, measurements of particle stability in existing circular accelerators will be reviewed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638315

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Based on a recent ICFA mini‐workshop held in Oxford, England [1], this paper surveys the computer codes available for simulating the behaviour of charged particle beams under space charge. Modelling tools for both linear and circular accelerating systems are covered. Lists of recent comparisons code v. code and code v. experiment are given and a set of experimental results that might be used to benchmark codes is identified. The Oxford workshop also drew up a detailed spreadsheet of the features of most of the simulation codes in current use, and this is available at [2]. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638316

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

One of the primary concerns in the operation of high‐power accelerators is machine componentradio‐activation caused by uncontrolled beam loss. Beam collimation and halo cleaning play a crucial role in minimizing uncontrolled beam loss. This paper reviews past experience, and discusses design principle, operational strategy, and challenging issues in beam cleaning in high‐power accelerators like the Spallation Neutron Source (SNS) and the Japan Proton Accelerator Research Complex (J‐PARC). © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638317

出版商:AIP    

年代:1903

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.1638318

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Beginning with the TRISPAL project, halo formation has been extensively studied at CEA last 10 years. Effect of mismatching, non‐linear forces, resonances, longitudinal‐transverse coupling, intrabeam scattering, and interaction with the residual gas have been explored. They have been studied theoretically from both analytical models and dedicated simulation codes and, for some of them, experimentally from proton beam profile measurements over a high dynamic range in a 26 periods FODO channel. Our knowledge, strongly improved through collaborations with our worldwide colleagues, has been applied to the design of several linac projects, whose last are SPIRAL2 and RX2. The goal of this presentation is to summarise the contribution of the CEA teams to the understanding of the halo formation. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638319

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The proposed Rare Isotope Accelerator (RIA) Facility, an innovative exotic‐beam facility for production of high‐quality energetic beams of short‐lived isotopes, will contain two superconducting linacs. To produce sufficient intensities of secondary beams the driver linac will provide 400 kW accelerated beams of any ion from hydrogen to uranium. A detailed design has been developed for the focusing‐accelerating lattice of the RIA driver linac which is configured as an array of short SC cavities, each with independently controllable rf phase. To obtain high‐power heavy‐ion beams the driver linac uses simultaneous acceleration of multiple charge states and two strippers. End‐to‐end beam dynamics simulations in six‐dimensional phase space were applied to study all possible sources of beam halo formation in the driver linac. The concept of a “beam‐loss‐free” linac is developed and implies beam halo collimation in designated areas. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1638320

出版商:AIP    

年代:1903

数据来源: AIP