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[en] Measurements of the beam position along an accelerator are typically treated equally using standard SVD-based orbit correction algorithms so distributing the residual errors, modulo the local beta function, equally at the measurement locations. However, sometimes a more stable orbit at select locations is desirable. In this paper, we introduce an algorithm for weighting the beam position measurements to achieve a more stable local orbit. The results of its application to close-orbit correction and 10 Hz orbit feedback are presented.
[en] The presence of realistic errors in an accelerator or in the model used to describe the accelerator are such that a measurement of the beam trajectory may deviate from prediction. Comparison of measurements to model can be used to detect such errors. To do so the initial conditions (phase space parameters at any point) must be determined which can be achieved by fitting the difference orbit compared to model prediction using only a few beam position measurements. Using these initial conditions, the fitted orbit can be propagated along the beam line based on the optics model. Measurement and model will agree up to the point of an error. The error source can be better localized by additionally fitting the difference orbit using downstream BPMs and back-propagating the solution. If one dominating error source exist in the machine, the fitted orbit will deviate from the difference orbit at the same point.
[en] The present invention relates to a control system of the sweep of a target (either fixed or mobile target) by a beam of particles. Said device comprises means of measuring and recording the relative positions of the particle beam and said target. It comprises also means of measuring and recording an electric current which is function of the intensity of the particle beam hitting the target, and means of displaying on a support (either the screen of an oscillograph or a paper sheet) a signal whose intensity or thickness at every point of said support is proportional to the intensity of the particle beam hitting said target, the coordinates of said point on the support displaying the relative position of said particle beam and said target
[fr]La presente invention concerne un dispositif de controle du balayage d'une cible par un faisceau de particules (cible fixe ou cible mobile). Le dispositif comprend des moyens pour representer mesurer et enregistrer la position relative du faisceau de particules et de ladite cible. Il comporte egalement des moyens pour mesurer et enregistrer un courant electrique fonction de l'intensite du faisceau de particules incidentes sur la cible, et des moyens pour representer sur un support, ecran d'oscilloscope ou feuille de papier, un signal dont l'intensite (ou l'epaisseur) en chaque point dudit support est proportionnelle a l'intensite du faisceau de particules arrivant sur ladite cible. Les coordonnees de ce point sur le support sont representatives de la position relative dudit faisceau de particules et de ladite cible
[en] Emittance measurements using the vernier scan technique give reliable results for 250 GeV protons even though the transverse beam profiles have non-Gaussian tails. Those non-Gaussian tails were observed for the first time this run at the 250 GeV beam energy. The vernier scan measurements are in excellent agreement with the emittances derived from collision rates and show practically no fill to fill scatter if compared to the latter. The results are consistent with a β* of 0.7 m and round beams. The IPM measurements show a discrepancy of up to 80% compared with the vernier scan data and a fill to fill scatter of up to 30%. If an uncertainty in the beta-function at the location of the IPM is the root cause, this uncertainty seems to be quite large. In any case, such an uncertainty could not explain the fill to fill variations of up to 30% which indicate yet another underlying reason that could explain fill to fill variations (candidates could be beam intensity issues with the IPM, beam position at the IPM, varying background etc.).
[en] Since the beginning of this commissioning period (November-December,1998), the closed orbit drift of a few millimeters in both horizontal and vertical planes in the High Energy Ring (HER) has been observed. Because optics, coupling and beam size in the ring depend on the closed orbit, the drifting of the orbit makes systematic improvement of the machine very difficult if not impossible. It is very difficult to keep any experiments repeatable, which is crucial for studying the instabilities in the machine. In this note, we will present some initial measurements and analysis of the problem