The Integrable Optics Test Accelerator (IOTA) is a storage ring for advanced beam physics research currently being built and commissioned at Fermilab. It will operate with protons and electrons using injectors with momenta of 70 and 150 MeV/c, respectively. The research program includes the study of nonlinear focusing integrable optical beam lattices based on special magnets and electron lenses, beam dynamics of space-charge effects and their compensation, optical stochastic cooling, and several other experiments. In this article, we present the design and main parameters of the facility, outline progress to date and provide the timeline of the construction, commissioning and research. The physical principles, design, and hardware implementation plans for the major IOTA experiments are also discussed.
A novel concept of controlled halo removal for intense high-energy beams in storage rings and colliders is presented. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as a tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collimator extends conventional collimation systems beyond the intensity limits imposed by tolerable losses. The concept was tested experimentally at the Fermilab Tevatron proton-antiproton collider. The first results on the collimation of 980-GeV antiprotons are presented. PACS numbers: 29.20.db, 41.85.Si Keywords: storage rings and colliders; beam collimation; magnetically confined electron beams; beam diffusion In high-energy particle accelerators and storage rings, the collimation system must protect equipment from intentional and accidental beam aborts by intercepting particle losses [1][2][3]. Its functions include controlling and reducing the beam halo, which is continually replenished by various processes such as beam-gas scattering, intrabeam scattering, electrical noise in the accelerating cavities, ground motion, betatron resonances, and beam-beam collisions. Uncontrolled losses of even a small fraction of the circulating beam can damage components, quench superconducting magnets, or produce intolerable experimental backgrounds. Collimators also serve as a diagnostic tool for fundamental machine measurements, such as transverse admittances, beam vibrations, and diffusion rates.Conventional collimation schemes are based on scatterers and absorbers, possibly incorporating several stages. The primary collimators (or targets) are the devices closest to the beam. They generate random transverse kicks mainly via multiple Coulomb scattering. In the Tevatron, the primary collimators are 5-mm tungsten plates positioned about 5 standard deviations (σ ) away from the beam axis. The random multiple-scattering kick has a root mean square (r.m.s.) of 17 µrad for 980-GeV protons. The betatron oscillation amplitude of the affected particles increases, and a large fraction of them is captured by the secondary collimators (or absorbers), suitably placed around the ring. In the Tevatron, the absorbers are 1.5-m steel blocks at 6σ .The conventional two-stage system offers robust shielding of sensitive components and it is very efficient in reducing beam-related backgrounds at the experiments. However, it has limitations. In high-power accelerators, the minimum distance between the collimator and the beam axis is limited by instantaneous loss rates, radiation damage, and by the electromagnetic impedance of the device. Moreover, beam jitter, caused by ground motion and other vibrations and partly mitigated by active orbit feedback, can cause periodic bursts of losses at aperture restrictions.
No abstract
The Tevatron in Collider Run II (2001-present) is operating with 6 times more bunches, many times higher beam intensities and luminosities than in Run I (1992)(1993)(1994)(1995). Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams have been significant sources of beam loss and lifetime limitations. We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in operations, predict the performance for planned luminosity upgrades, and discuss ways to improve it.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.