摘要:

A formalism for extracting coupled betatron parameters from multiturn, shock excited, beam position monitor data is described. The most important results are nonperturbative in that they do not rely on the underlying ideal lattice model. Except for damping, which is assumed to be exponential and small enough to be removed empirically, the description is symplectic. As well as simplifying the description, this leads to self‐consistency checks that are applied to the data. The most important of these is a ‘‘magic ratio’’ of Fourier coefficients that is required to be a lattice invariant, the same at every beam position monitor. All formulas are applied to both real and simulated data. The real data were acquired June 1992 at LEP as part of decoupling studies, using the LEP beam orbit measurement system. Simulated data, obtained by numerical tracking (TEAPOT) in the same (except for unknown errors) lattice, agrees well with real data when subjected to identical analysis. For both datasets, deviations between extracted and design parameters and deviations from self‐consistency can be accounted for by noise and signal‐processing limitations. This investigation demonstrates that the LEP beam position system yields reliable local coupling measurements. It can be conservatively assumed that systems of similar design at the SSC and LHC will provide the measurements needed for local decoupling.

ISSN:0094-243X    

DOI:10.1063/1.45103

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

In this paper we present the proposed scheme for reducing the nonlinear chromaticity of the collider in the collision mode. Briefly, the optics of the collider lattice with special emphasis on the interaction regions which are the main sources of chromaticity are discussed. Then, a theoretical calculation of the second‐order chromaticity in a storage ring is discussed. Next we focus on the second‐order tune shift due to the triplets, the domain sources of chromaticity in the interaction regions. The fifth topic is the theory behind our proposed scheme for correcting higher‐order chromaticity. The last concerns of this paper are evaluation of the chromatic performance of the proposed scheme and the effect of the chromaticity‐correcting sextupoles on the dynamics aperture. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.45104

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Synchrotron motion in the IUCF cooler ring was studied using turn‐by‐turn beam tracking on ten‐turn intervals, where the beam phase relative to the rf and the closed‐orbit position in a high‐dispersion region were measured. The synchrotron tune shift with amplitude was measured and is compared with theory. The driven response of the system was also studied using the same techniques, and was found to share many of the same characteristics of other parametric resonant systems. The experimental results did not exhibit any effects of bunch decoherence expected from the tune shift with amplitude.

ISSN:0094-243X    

DOI:10.1063/1.45106

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Recently the Hamiltonian of particle motion near a resonance condition was deduced at the Indiana University Cyclotron Facility Cooler Ring. It was found that linear betatron coupling complicated the analysis. A coupling correction scheme is described which reduced the coupling coefficient from 0.03 to 0.0012. When particles were kicked onto resonance islands with the coupling reduced, the island motion was stable for upwards of 1×106turns. This stable island motion allowed for the determination of higher‐order terms in the Hamiltonian.

ISSN:0094-243X    

DOI:10.1063/1.45129

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Progress in the use of one‐turn maps for long‐term tracking of particles—useful in dynamic aperture studies on large circular accelerators—is reviewed briefly. It is recommended that long‐term tracking of particles for large circular accelerators such as the Superconducting Super Collider (SSC) or its high‐energy booster be performed with one‐turn maps. The advantages are twofold: not only is tracking speed dramatically enhanced (by about two orders of magnitude for the SSC), but one‐turn‐map tracking also offers an easier reliability check of the tracking results and easier order‐by‐order analysis.

ISSN:0094-243X    

DOI:10.1063/1.45107

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We present some of the results of our tracking investigations using PATRIS. Both short‐term and long‐term tracking, using large numbers of particles, were performed and analyzed. When switching from short‐term (1000 turns) to long‐term (the maximum achieved was 10 million turns) tracking mode, we observed a small (about 14%) reduction of the dynamic aperture. We also empirically confirmed that the distinction between short‐term and long‐term tracking becomes meaningful for a number of turns of the order of 100,000 rather than 10,000, i.e. that 105is the threshold which must be crossed to get any appreciable difference between a 1000‐turn run and a longer one. We have also found that a high density of initial conditions employed in tracking is somewhat more important for accurate determination of the dynamic aperture than a large number of turns.

ISSN:0094-243X    

DOI:10.1063/1.45108

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The Fermilab Main Injector is a new 150‐GeV proton synchrotron, designed to replace the Main Ring and improve the high energy physics potential of Fermilab. The status of the Fermilab accelerator complex upgrade will be discussed. Study of the stability of the beam in the Main injector will be discussed. Detuning and corrector schemes to improve the dynamic aperture of the Main Injector will be presented. Tune modulation caused by octupolar detuning will be discussed.

ISSN:0094-243X    

DOI:10.1063/1.45109

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A new magnet sorting method for accelerators is developed. It is based on the linearized analysis of the effects of errors on accelerators. It is implementable in two steps. The first step is completely analytical in character while the second step involves the comparison of computed values with the measured error values. The whole process is repeated at mostntimes, wherenis the number of magnets to be chosen from at a time. Simulations of the method, using Mathematica(R), have been implemented for sorting the APS injector synchrotron dipoles and quadurpoles with excellent results.

ISSN:0094-243X    

DOI:10.1063/1.45110

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

This paper tries to make clear what limits the validity of a Taylor series map, and how. We describe the concept of a transfer map and quote some theorems that justify not only their existence but also their advantages. Then, we describe the Taylor series representation for transfer maps. Following that, we attempt to elucidate some of the basic theorems from the theory of functions of one and several complex variables. This material forms the core of our understanding of what limits the domain of convergence of Taylor series maps. Lastly, we use the concrete example of a simple anharmonic oscillator to illustrate how the theorems from several complex variable theory affect the domain convergence of Taylor series maps. There we describe the singularities of the anharmonic oscillator in the complex planes of the initial conditions, show how they constrain our use of a Taylor series map, and then discuss our findings. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.45111

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The available momentum space of a FODO lattice is determined by the maximum value of the dispersion function (&dgr;x=Dx∂p/p). In a regular FODO lattice the dispersion function oscillates between its maximum and minimum values, which are always positive. The maximum value of the dispersion function in a FODO cell of a fixed length depends on the cell phase difference. An example of a new lattice, in which the dispersion function is lowered to half its value in the same FODO cell, is presented. The available momentum space in the new lattice is raised to twice that in the FODO lattice by allowing the dispersion function to oscillate between the same positive and negative values. The maxima of the dispersion function in the new lattice have half the value of those within the regular 90° cells.

ISSN:0094-243X    

DOI:10.1063/1.45112

出版商:AIP    

年代:1992

数据来源: AIP