The 1991 dynamic aperture experiment at the CERN SPS

Altuna, X.; Arimatea, C.; Bailey, R.; Bohl, Thomas; Brandt, D.; Cornelis, K.; Depas, C.; Galluccio, F.; Gareyte, J.; Giachino, Rossano; Giovannozzi, M.; Guo, Zhen; Herr, W.; Hilaire, Amanda St.; Lundberg, T.; Miles, J.; Normann, L.; Risselada, T.; Scandale, W.; Schmidt, F.; Spinks, Alan; Venturini, M.

doi:10.1063/1.42289

Cited by 10 publications

(11 citation statements)

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“…In this model, the mapping Equation (2) has been eliminated; instead, each particle has been described by a constant tune determined by its initial amplitude a = JX 2 + y2 +pi +p~. The tune shift dependence 811(r) has been calculated using the first-order term of the perturbation theorya 811(a) =~~(1-1°(:) ex p ( -: ) ) , (9) where 1 0 is the zero-order modified Bessel function. This case differs in many respects from the nonlinear model because each particle represents a linear oscillator so that nonlinear resonances are eliminated from the particle dynamics.…”

Section: Simulations Results For the Basic Modelmentioning

confidence: 99%

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Computer simulation of the emittance growth due to noise in large hadron colliders

Lebedev¹

1993

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The problem of emittance growth due to random fluctuations of the magnetic field in a hadron collider is considered. The results of computer simulations are compared with the analytical theory developed earlier.A good agreement was found between the analytical theory predictions and the computer simulations for the collider tunes located far enough from high-order betatron resonances. The dependence of the emittance growth rate on noise spectral density, beam separation at the interaction point (IP), and the value of beam separation at long range collisions is studied. The results are applicable to the Superconducting Super Collider (SSC).

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Section: Simulations Results For the Basic Modelmentioning

confidence: 99%

“…The main reason for this growth is that the spectral density of external perturbation grows rapidly with frequency, decrease and this generates a larger emittance growth. 9 Required BPM resolution was calculated with the use of Equation (18) is canceled in the equation.…”

Section: Discussionmentioning

confidence: 99%

Computer simulation of the emittance growth due to noise in large hadron colliders

Lebedev¹

1993

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“…Typically, a few distinct frequencies feature much higher amplitudes and therefore, the focus of these studies was also to highlight the impact of a few distinct frequency lines. It was derived theoretically [8] as well as proven experimentally [4,5] that several frequencies in the noise spectrum are significantly more harmful than a single one. This knowledge was then applied to the LHC [11] and more recently to the HL-LHC [12][13][14] resulting in strict tolerances for the noise generated by the power converters.…”

Section: Introductionmentioning

confidence: 98%

“…All these magnets are installed at locations with high beta function and the beam is therefore particularly sensitive to any changes in the magnetic field of these magnets. The impact of the field fluctuations due to power supply noise, or the so called ripple, on the beam lifetime has been studied in the past in particular at the Super Proton Synchrotron (SPS) at CERN [4][5][6][7], the Hadron Electron Ring Facility (HERA) at DESY [8,9] and the TEVATRON at FERMILAB [10]. In the case of the SPS a tune ripple of 10 −4 turned out to be acceptable while experiences at HERA showed that a tune ripple of 10 −5 for low frequencies and 10 −4 for high frequencies could lead to a significant decrease in lifetime.…”

Section: Introductionmentioning

confidence: 99%

Magnetic frequency response of High-Luminosity Large Hadron Collider beam screens

Morrone

Martino

Maria

et al. 2019

Phys. Rev. Accel. Beams

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Magnetic fields used to control particle beams in accelerators are usually controlled by regulating the electrical current of the power converters. In order to minimize lifetime degradation and ultimately luminosity loss in circular colliders, current-noise is a highly critical figure of merit of power converters, in particular for magnets located in areas with high beta-function, like the High-Luminosity Large Hadron Collider (HL-LHC) insertions. However, what is directly acting upon the beam is the magnetic field and not the current of the power converter, which undergoes several frequency-dependent transformations until the desired magnetic field, seen by the beam, is obtained. Beam screens are very rarely considered when assessing or specifying the noise figure of merit, but their magnetic frequency response is such that they realize relatively effective low pass filtering of the magnetic field produced by the system magnet-power converter. This work aims at filling this gap by quantifying the expected impact of different beam screen layouts for the most relevant HL-LHC insertion magnets. A well-defined postprocessing technique is used to derive the frequency response of the different multipoles from multiphysics finite element method (FEM) simulation results. In addition, a wellapproximated analytical formula for the low-frequency range of multi-layered beam screens is presented.

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“…Several experiments, which used the diffusion process, had been performed at different accelerators to measure the acceptance or the dynamic aperture. The particle diffusion was obtained by either using noise applied transversely to the beam [7] or using the ripple in the field of the magnets [8]. The latter method led to a stochastic detuning of the particles which generates transverse diffusion.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the acceptance by means of transverse beam excitation with noise

Sorge

Franchetti

Parfenova

2011

Phys. Rev. ST Accel. Beams

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In this work, we present a technique to measure the acceptance of a circular accelerator extending a previous method by the measurement of particle loss. Here, we apply an rf voltage to transversely excite a coasting heavy ion beam in the SIS-18 synchrotron at GSI. The resulting growth of the transverse beam width causes particle loss when the beam width exceeds the limiting aperture. The acceptance is determined from the measured time evolution of the beam current after particles start to hit the aperture. In doing so, the result will not depend on the initial width of the ion beam.

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The 1991 dynamic aperture experiment at the CERN SPS

Cited by 10 publications

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Computer simulation of the emittance growth due to noise in large hadron colliders

Computer simulation of the emittance growth due to noise in large hadron colliders

Magnetic frequency response of High-Luminosity Large Hadron Collider beam screens

Measurement of the acceptance by means of transverse beam excitation with noise

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