Feasibility Study of Beam-Beam Compensation in the Tevatron with Wires (original) (raw)
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Study of Long-range Collisions and Wire Compensation for Tevatron Run-II
This report summarizes studies of long-range collisions and their compensation by current carrying wires for the Tevatron Run-II, which were performed during a two-week stay at Fermilab, February 22 to March 8, 2004. The weak-strong code WSDIFF was significantly extended to simulate the actual long-range encounters at the Tevatron for different antiproton bunches in the train at injection and in collision. Tune footprints and diffusive apertures simulated by this code are presented for various cases, differing in the bunch position, the energy, the number of long-range and head-on collisions, the presence of additional compensating wires and the momentum deviation. It is confirmed that the solution of 4 wires for injection, previously found by B. Erdelyi, raises the dynamic aperture, by about 1.0-1.5σ. For both injection and collision an ideal compensation of the 6 or 3 closest long-range encounters was modeled, by removing these collisions altogether. At collision, an improvement in the dynamic aperture of the order of 0.5-1.0σ is found. The much more copious residual long-range collisions are shown to also strongly affect the diffusive aperture, however, which highlights a lack of correlation between dynamic aperture and tune footprints. The dynamic aperture widely varies with the bunch number, ranging from 5 to 8σ along the train, in collision for on-momentum particles. Analytical calculations of tune shift, coupling, chromaticity and chromatic coupling similarly reveal a large variation from bunch to bunch, amounting to 16 units in chromaticity and 4 or 5 units in chromatic coupling. Achieving compensation for all bunches in the train appears a nontrivial challenge for dc wires, in particular if off-energy is also to be corrected. In a machine study on March 1, the Tevatron electron lens was used to simulate a wire and the dependences of beam lifetime, tune, emittances and bunch length on the beam-TEL distance were explored. The results of this experiment are reported elsewhere [1].
Considerations on compensation of beam-beam effects in the Tevatron with electron beams
Physical Review Special Topics - Accelerators and Beams, 1999
The beam-beam interaction in the Tevatron collider sets limits on bunch intensity and luminosity. These limits are caused by a tune spread in each bunch which is mostly due to head-on collisions, but there is also a bunch-to-bunch tune spread due to parasitic collisions in multibunch operation. We propose to compensate these effects with the use of a countertraveling electron beam, and we present general considerations and physics limitations of this technique.
Tevatron Beam-Beam Compensation Project Progress
Proceedings of the 2005 Particle Accelerator Conference, 2005
In this paper, we report the progress of the Tevatron Beam-Beam Compensation (BBC) project . Proton and antiproton tuneshifts of the order of 0.009 induced by electron beam have been reported in [2], suppression of an antiproton emittance growth in the Tevatron High Energy Physics (HEP) store has been observed, too [1]. Currently, the first electron lens (TEL1) is in operational use as the Tevatron DC beam cleaner. Over the last two years, we have greatly improved its reliability. The 2nd Tevatron electron lens (TEL2) is under the final phase of development and is being prepared for installation in the Tevatron in 2005.
2007 IEEE Particle Accelerator Conference (PAC), 2007
Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams are significant sources of beam loss and lifetime limitations in the Tevatron Collider Run II (2001-present). 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 high energy physics (HEP) operation, predict the performance for planned luminosity upgrades and discuss ways to improve it.
Compensation of beam-beam effects in the Tevatron collider with electron beams
1999
The beam-beam interaction in the Tevatron collider sets limits on bunch intensity and luminosity. These limits are caused by a tune spread in each bunch which is mostly due to head-on collisions, but there is also a bunch-to-bunch tune spread due to parasitic collisions in multibunch operation. We propose to compensate these effects with use of a countertraveling electron beam, and present general considerations and physics limitations of this technique
2024
In high intensity and high energy colliders, such as the CERN Large Hadron Collider (LHC) and its future high-luminosity upgrade, interactions between the two beams around the different interaction points impose machine performance limitations. In fact, their effect reduces the beam lifetime, and therefore, the collider's luminosity reach. Those interactions are called beam-beam long-range (BBLR) interactions, and a possible mitigation of their effect using dc wires was proposed for the first time in the early 2000's. This solution is currently being studied as an option for enhancing the HL-LHC performance. In 2017 and 2018, four demonstrators of wire compensators have been installed in the LHC. A 2-yearlong experimental campaign followed in order to validate the possibility to mitigate the BBLR interactions in the LHC. During this campaign, a proof-of-concept was completed and motivated an additional set of experiments, successfully demonstrating the mitigation of BBLR interactions effects in beam conditions compatible with the operational configuration. This paper reports in detail the preparation of the experimental campaign, including the corresponding tracking simulations and the obtained results, and draws some perspectives for the future.
Theory and Observations of Beam-beam effects at the Tevatron
Long-range beam-beam interactions in Run II at the Tevatron are the dominant sources of beam loss and lifetime limitations of anti-protons, especially at injection energy. I discuss observations and theoretical understanding of these beambeam effects.
Experimental studies of beam-beam effects in the Tevatron
2003
The long-range beam-beam interactions limit the achievable luminosity in the Tevatron. During the past year several studies were performed on ways of removing the limitations at all stages of the operational cycle. We report here on some of these studies, including the effects of changing the helical orbits at injection and collision, tune and chromaticity scans and coupling due to the beam-beam interactions.
Experimental studies of compensation of beam–beam effects with Tevatron electron lenses
New Journal of Physics, 2008
Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a highenergy collider . In this article we present the results of various beam experiments with "electron lenses," novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.
High luminosity operation, beam-beam effects and their compensation in Tevatron
2008
Over the past 2 years the Tevatron peak luminosity steadily progressed and reached the level of 3.15 · 10³² cm² s¹ which exceeds the Run II Upgrade goal. We discuss the collider performance, illustrate limitations and understanding of beam-beam effects and present experimental results of compensation of the beam-beam effects by electron lenses--a technique of great interest for the LHC.