85527168
A METHOD TO MEASURE THE BETA-BEATING IN A 90 DEGREES PHASE ADVANCE LATTICE
A method to compute the beta-beating in an accelerator, using as input the measurement of the phase advance of a betatron oscillation between three BPMs (beam position monitors), had been developed in the past[1]. The beauty of this method is that the result does not depend on the the BPM relative errors on the measurement of the oscillation amplitude. Unfortunately this method is not applicable when the phase advance between two of the three BPMs is (close to) 180 degrees. In this latter case the measurement of the amplitude of the beam oscillation should be combined with the phase advance measurement to get a complete picture of the beta-beating. Detecting and filtering BPMs with large gain errors requires some care. A method dealing with these aspects has been developed. Examples obtained by applying the method to real data from LEP and SPS are shown.
10489447
LEP OPERATION AND PERFORMANCE WITH 100 GEV COLLIDING BEAMS
Luminosity production in LEP was extended to 101 GeV beam energy in 1999 and 104.4 GeV in 2000. The performance was continually optimised, resulting in 1999 peak and integrated luminosities higher than in any previous year of LEP operation. In particular, the beambeam tune shift reached 0.083 per interaction point. This was achieved with the help of a faster luminosity monitoring, a new tune working point, a reduced design vertical dispersion and new dispersion and coupling optimisation tools. A higher beam rate from the injectors, a better injection efficiency, a faster ramp and a newly automated control of the horizontal damping partition number J x maximised the time available for physics and thus contributed to the higher integrated luminosity.
61569699
The RTC-a software support system for the control of the CERN SPS
The RTC (Run Time Coordinator) is described. It is a software support system designed for the SPS (Super Proton Synchrotron) control system to provide a run time environment for application software. It coordinates the execution of individual programs or processes and supervises the process control, i.e. process synchronization, interprocess communication, data transfer, and operator I/O (input/output). This supervision includes the control of processes distributed on a Unix-based network. A standard language independent data interface is part of the system. The system includes tools for data presentation, error logging, and contention resolution. Separating system-dependent features for the body of the application programs leads to high flexibility and simplifies the software development. The basic philosophy of the RTC is discussed and its implementation is described.<<ETX>>
54676169
Measurement of chromatic effects in LEP
The chromaticity produced by the insertions and the lattice of LEP is corrected in the FODO lattice of the arcs which has horizontal and vertical phase advances of 90/spl deg/ and 60/spl deg/ for the LEP optics presently used. This is done with two horizontal and three vertical sextupole families. To check this correction scheme the non-linear chromaticities have been measured by observing the betatron tunes as a function of RF-frequency, i.e. of momentum deviation. The differences between the results and the expected effects of the sextupoles are interpreted in terms of octupole and decapole components in the dipole magnets. To check the distribution around the ring of the chromaticities and their corrections the betatron phase advances have been measured as a function of momentum deviation. This was done by observing an excited betatron oscillation for 1024 turns in all beam position monitors for different RF-frequencies. The results clearly show the negative chromaticity produced in the straight sections and its correction in the arcs. The parasitic sextupole components are found to be spread uniformly in the arcs within the measurement errors. Under this condition one finds that they have a negligible effect on the dynamic aperture.
12798237
Overview of LEP operation in 1998
After the installation of 32 additional RF cavities in the 1997-1998 shutdown LEP was operated at a beam energy of 94.5 GeV. The total integrated luminosity for the year 1998 clearly surpassed its target and reached 198 pb/sup -1/. Vertical beam-beam tuneshifts of more than 0.07 were obtained. The performance did not seem to be beam-beam limited, but the total beam current was limited by power dissipation problems to around 6 mA. A high phase advance optics (102/spl deg/, 90/spl deg/), with a smaller natural emittance, was used for regular operation in 1998. This contributed to the excellent performance of LEP, together with the further reduction of both the horizontal and vertical beta function at the interaction points. No dynamic aperture problems were encountered.
107933425
First trial of BOM harmonic analysis
120885277
Demodulation and detection of correlations in a beam by a scattering detector
Abstract The demodulation and the detection of correlations in a beam using a detector that scatters the beam is discussed employing a localized wave packet description of the beam. It is shown that a simple very general formula for the spectral excitation function of the detector can be given; by spectral excitation function we mean the rate of excitation of the detector to a given level. The formula is derived without making specific assumptions on the nature of the detector. The spectral excitation function is naturally decomposed as a sum of four terms: Two of these (the B terms in what follows) depend only on the wavefunction and stochastic distribution of the incident beam; they are proportional to the square (and higher powers) of the flux and contain all the information on the self-beat, Forrester-type effects and demodulation. More precisely, one of these B terms contains the information on the demodulation and the other on the beat effects. The remaining two terms (to be called the A terms) describe the conventional inelastic scattering (proportional to the flux) and some coherent corrections to it (proportional to higher powers of the flux): These A terms behave as noise if the signal of interest is that described by the B terms. The theory is illustrated with many examples to known situations; particular attention is given to some conceptual questions involved.
12690675
The general QCD parametrization and the large Nc description: Some remarks
Stimulated by a recent paper of Buchmann and Lebed,a comparison is presented of the two methods mentioned in the title for treating hadron properties in QCD.Doubts arise on the equivalence of the large Nc description to real QCD. (PACS: 12.38.Aw; 11.15.Pg; 13.40.Dk)
118006705
Parametrizing the baryon magnetic moments
123219822
CONNECTION BETWEEN BBP AND VPP VERTICES IN THE QUARK MODEL
125470398
The Nonrelativistic quark model from QCD and related topics