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[en] Integrated charge collected on the sense wires of wire-scanner systems utilized to determine beam profile is generally the parameter of interest. The LANSCE application requires capturing the charge information macropulse-by-macropulse with macropulse lengths as long as 700 (micro)s at a maximum macropulse rate of 120 Hz. Also, for the LANSCE application, it is required that the integration be performed in a manner that does not require integrator reset between macropulses. Due to the long macropulse which must be accommodated and the 8.33 ms minimum pulse period, a simple R-C integrator cannot be utilized since there is insufficient time between macropulses to allow the integrator to adequately recover. The application of wide analog bandwidth to provide accurate pulse-by-pulse capture of the wire signals with digital integration of the wire signals to determine captured charge at each macropulse in applications with comparatively long macropulses and high pulse repetition rates is presented.
[en] We present an overview of the status of ongoing work on physics models describing beam matching and halo control for particle accelerators, particularly high power ion linacs. We consider moments and various new variables that more naturally describe beam halo evolution. We compute matched beams and ''mode invariants'' (analogs of moment invariants) using primarily symbolic techniques
[en] A scraper scan - sending a scraper through a particle beam while measuring the intensity as a function of scraper position - is a common method of determining the profile of the beam. At first glance, this seems to be a rather simple procedure. Nevertheless, some care is required in the acquisition of the data and in the analysis if one is going to achieve an accurate result.
[en] Based on the extended Huygens—Fresnel integral, analytical propagation expressions for the rms beam width and angular of partially coherent elegant Hermite cosh Gaussian beam (EHChGB) in non-Kolmogorov turbulence are derived. The effects of exponent value, inner and outer scales of non-Kolmogorov turbulence on partially coherent EHChGB are investigated quantitatively. (paper)
[en] Within the halo experiment presently being conducted at the Low Energy Demonstration Accelerator at Los Alamos National Laboratory, specific beam instruments that acquire horizontally and vertically projected particle-density distributions out to greater than 105:1 dynamic range are located throught the 52-magnet halo lattice.
[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] The sensing wire of the metering device for the beam profile is rotated through the ion beam with the help of an eccentric arm in such a way that the whole cross-section can be sensed. The secondary electrons produced by the ions when they collide with the sensing wire are sucked off laterally towards a channel electron multiplier for purposes of actual metering. The collecting funnel for the secondary electrons is placed behind an opening of a screening plate. (DG)
[de]Der Fuehldraht der Messvorrichtung des Strahlprofils wird mittels eines Exzenterarms so durch den Ionenstrahl gedreht, dass der gesamte Querschnitt abgetastet wird. Die von den Ionen beim Auftreffen auf den Fuehldraht erzeugten Sekundaerelektronen werden zur eigentlichen Messung zu einem Kanalelektronenvervielfacher hin seitlich abgesaugt. Der Auffangtrichter fuer die Sekundaerelektronen steht hierbei hinter einer Oeffnung eines Abschirmbleches. (DG)
[en] The authors have developed an apparatus able to generate ID intensity-modulated beams, using only one moving absorber within the irradiation field. A procedure for deriving optimized absorber-speed profiles in order to produce the desired fluence/dose profiles has been suggested. Experimental tests show that the system should be sufficiently reliable in reproducing modulated beams profiles of different shape: expected relative doses against measured relative doses have been found to be in agreement in a number of situations within 3% using a non-focused device. A better agreement should be expected using a focused apparatus (which is currently being developed). Beam modulation by single absorber cannot modulate the beam fluence in any way one wishes, due to physical constraints, which depend on the absorber and field widths and on the shape of the desired fluence profile. However, the authors show that this simple and low-cost tool could offer, with a sufficient degree of accuracy, the possibility of modulating the beam fluence with a high degree of versatility. In particular, a proceedure for performing tissue-missing compensation by single-absorber dynamic beam modulation is suggested. (author)