Feasibility Study of Beam-Beam Compensation in the Tevatron with Wires (original) (raw)
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
Stabilizing Low Frequency Beam Motion in the Tevatron
Proceedings of the 2005 Particle Accelerator Conference, 2005
A feed back orbit stabilization system is being developed using a set of BPMS and existing Tevatron corrector magnets to stabilize beam motion up to 50 microns below 25 Hz. The construction of this system is described and the stability limits and magnitude of beam motion reduction is explored.
Tevatron beam-beam simulations at injection energy
Major issues at Tevatron injection are the effects of 72 long-range beam-beam interactions together with the machine nonlinearity on protons and anti-protons. We look at particle tracking calculations of Dynamic Aperture (DA) under present machine conditions. Comparisons of calculations with observations and experiments are also presented in this report.
Long-Term Simulation of Beam-Beam Effects in the Tevatron at Collision Energy
Proceedings of the 2005 Particle Accelerator Conference, 2005
The beam-beam effect is a significant source of nonlinearities in the Tevatron. We have developed a code which allows us to estimate its contribution to the finite lifetime of the anti-proton beam, both at collision and injection energy, by tracking realistic particle distribution for a high number of terms and extrapolating from the particle loss rate. We describe the physical modeling underlying the code and give benchmarking results.
JACoW : Progress with Long-Range Beam-Beam Compensation Studies for High Luminosity LHC
2017
Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller β* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab cavities. Both beam losses and emittance growth could be mitigated by compensating the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing wires embedded into collimator jaws, installed either side of the high luminosity interaction regions. For HL-LHC two options are considered, a current-bearing wire as for the demonstrator, or electron lenses, as the ideal distance between the particle beam and compensating current may be too small to allow the use of solid materials. This paper reports on the ongoing activities for both options, covering the progress of the wire-in-jaw collimators, the foreseen LRBB experiments at the LHC, and first considerations for the design of the electron lenses to ultimately replace material wires for HL-LHC.
Beam losses at injection energy and during acceleration in the Tevatron
2003
Protons and anti-protons circulate on helical orbits in the Tevatron. At injection energy (150 GeV) the lifetimes of both species are significantly lower on the helical orbits compared to lifetimes on the central orbit but for different reasons. There are also significant beam losses in both beams when they are accelerated to top energy (980 GeV)-again for different reasons. We report on experimental studies to determine the reasons and on methods of improving the lifetimes and losses for both beams.