Experimental Evidence of Beam Trapping with one-third and one-fifth Resonance Crossing

Beam trapping in stable islands of the horizontal phase space generated by non-linear magnetic fields is realized by means of a given tune variation so to cross a resonance of order n. Whenever the resonance is stable, n + 1 beamlets are created whereas if the resonance is unstable, the beam is split in n parts. Experiments at the CERN Proton Synchrotron showed protons trapped in stable islands while crossing the one-third and one-fifth resonance with the creation of 3 and 6 stable beamlets, respectively. The results are presented and discussed

Progress in the Beam preparation for the Multi-Turn Extraction at the CERN Proton Synchrotron

A new type of extraction based on beam trapping inside stable islands in the horizontal phase space will become operational during 2008 at the CERN Proton Synchrotron. A series of beam experiments was carried out to prove lossless capture with high intensity and multi-bunched beams, up to $1.5 × 10^{13}$ protons per pulse, in preparation of the extraction commissioning. These fundamental steps for the new Multi-turn Extraction are presented and discussed in details

Adiabaticity and Reversibility Studies for Beam Splitting using Stable Resonances

At the CERN Proton Synchrotron, a series of beam experiments proved beam splitting by crossing the one-fourth resonance. Depending on the speed at which the horizontal resonance is crossed, the splitting process is more or less adiabatic, and a different fraction of the initial beam is trapped in the islands. Experiments prove that when the trapping process is reversed and the islands merged together, the final distribution features thick tails. The beam population in such tails is correlated to the speed of the resonance crossing and to the fraction of the beam trapped in the stable islands. Experiments and possible theoretical explanations are discussed

Baseline LHC machine parameters and configuration of the 2015 proton run

This paper shows the baseline LHC machine parameters for the 2015 start-up. Many systems have been upgraded during LS1 and in 2015 the LHC will operate at a higher energy than before and with a tighter filling scheme. Therefore, the 2015 commissioning phase risks to be less smooth than in 2012. The proposed starting configuration puts the focus on feasibility rather than peak performance and includes margins for operational uncertainties. Instead, once beam experience and a better machine knowledge has been obtained, a push in $\beta^*$ and performance can be envisaged. In this paper, the focus is on collimation settings and reach in $\beta^*$---other parameters are covered in greater depth by other papers in these proceedings.Comment: submitted for publication in a CERN yellow report (Proceedings of the LHC Performance Workshop - Chamonix 2014

Optics studies based on V6.503 nominal configuration

Optics studies based on the V6.503 nominal optics have been performed, aiming at improving the collimation efficiency by adjusting the phase advance from IP1 to IP5 to be π/2 off a multiple of 2π such that the off-momentum beta-beating is localized to the left side of the LHC ring. The off-momentum beta-beating in IR7 (betatron collimation section) is suppressed as expected. In addition to this main point, IR2 and IR8 injection optics are studied to improve the apertures of the inner triplet magnets. The aperture could be increased by either increasing beta* or improving the crossing scheme as proposed or bot

Optics Flexibility in the LHC at Top Energy

Flexibility of the LHC optics at top energy has been studied, in terms of betatron tune tunability, mainly for the high-beta optics that requires tunability of the order of half a unit. It has been shown that the tunability at top energy is good enough for the high-beta optics. The results obtained in this study could be useful for other optics and operation modes

Non-invasive single-bunch matching and emittance monitor

On-line monitoring of beam quality for high brightness beams is only possible using non-invasive instruments. For matching measurements, very few such instruments are available. One candidate is a quadrupole pick-up. Therefore, a new type of quadrupole pick-up has been developed for the 26 GeV Proton Synchrotron (PS) at CERN, and a measurement system consisting of two such pick-ups is now installed in this accelerator. Using the information from these pick-ups, it is possible to determine both injection matching and emittance in the horizontal and vertical planes, for each bunch separately. This paper presents the measurement method and some of the results from the first year of use, as well as comparisons with other measurement methods.Comment: 10 pages, 10 figures; added figure, minor textual additions; To be resubmitted to Phys. Rev. ST-A

Trajectory Correction in the Transfer Line TT2-TT10 for the Continuous Transfer (CT)

A new scheme for the trajectory correction in the TT2-TT10 transfer line for the Continuous Transfer (CT) extraction from the PS to the SPS has been developed together with a new software application, PS-CT-Check. In this note the algorithm, the software, and the results of the tests performed during the 2007 run are summarized. The PS-CT-Check user's manual is also provided. The scheme, with minor modifications, will be applied to the new Multi-Turn Extraction (MTE)

Experimental evidence of adiabatic splitting of charged particle beams using stable islands of transverse phase space

Recently, a novel technique to perform multi-turn extraction from a circular particle accelerator was proposed. It is based on beam splitting and trapping, induced by a slow crossing of a nonlinear resonance, inside stable islands of transverse phase space. Experiments at the CERN Proton Synchrotron started in 2002 and evidence of beam splitting was obtained by summer 2004. In this paper the measurement results achieved with both a low- and a high-intensity, single-bunch proton beam are presented