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[en] During the past years, significant progress has been made in understanding the beam transverse emittance blow-up and its preservation. However, one often finds him-/herself ignorant when he/she tries to explain what was observed in an existing machine or to predict what will happen in a machine under design. There are a number of such examples given in this report. Some of them are even fundamental. These are the challenges. But they are also the directions leading to new achievements. The workshop gladly acknowledged them and promised to work on them
[en] Though linac beam intensity is sufficient (about 15mA) optical beam properties were improved in order to fit the renewed Saturne transverse acceptance with a good factor of security. The low energy beam line located between the preinjector and the linac was modified according to the following needs: reduction of beam size in the buncher, more flexible beam emittance matching with the linac acceptance, taking into account space charge effects. Theoretical computation results are briefly given and the experimental results are discussed
[en] A new method for controlling longitudinal emittance growth during transition crossing in proton or heavy ion synchrotrons is described. Longitudinal focusing forces are eliminated near transition through the use of rf harmonics. The rf system provides only the required accelerating voltage to each particle in each bunch during the non-adiabatic period near transition, hence momentum growth is minimized. Bunch length is maximized just at transition, minimizing space charge forces and associated instabilities
[en] During the commissioning of EBIS beams in Booster in November 2010 and in April, May and June 2011, it was found that the transverse emittances of the EBIS beams just upstream of Booster were much larger than expected. Beam emittances of 11π mm milliradians had been expected, but numbers 3 to 4 times larger were measured. Here and throughout this note the beam emittance, πε0, is taken to be the area of the smallest ellipse that contains 95% of the beam. We call this smallest ellipse the beam ellipse. If the beam distribution is gaussian, the rms emittance of the distribution is very nearly one sixth the area of the beam ellipse. The normalized rms emittance is the rms emittance times the relativistic factor βγ = 0.06564. This amounts to 0.12π mm milliradians for the 11π mm milliradian beam ellipse. In (1) we modeled the injection and turn-by-turn evolution of an 11π mm milliradian beam ellipse in the horizontal plane in Booster. It was shown that with the present injection system, up to 4 turns of this beam could be injected and stored in Booster without loss. In the present note we extend this analysis to the injection of larger emittance beams. We consider only the emittance in the horizontal plane. Emittance in the vertical plane and the effects of dispersion are treated in (2).
[en] A primary purpose of the ATF Damping Ring is to demonstrate the small vertical emittance required for a future linear collider. In this report, we first describe the diagnostics available to measure this emittance. Then we discuss the dependence of the emittance on various parameters, such as the betatron tunes, vacuum pressure, and beam current, and, subsequently, study several methods of betatron-coupling correction. Next, we show that the interferometer used to determine the vertical beam size is sensitive to transverse beam tails and does not measure the core emittance, which could explain the observed sensitivity of the measured spot size to vacuum pressure and beam intensity. Finally, we summarize the results and propose a few further studies. In the appendix, we present recent measurements of the dynamic aperture, and discuss the variation of the beta functions, e.g., at the synchrotron light monitor, with the betatron tune. Here, we also present details of the SUSSIX program, by which, in the future, we hope to infer all linear coupling parameters as well as higher-order nonlinearities from turn-by-turn orbit data
[en] The influence of spatial and chromatic aberrations on the parameters of the 730 MeV beam extracted from a SALO recirculator is studied using numerical simulation. The influence of fringing fields and the heterogeneity of the guide field of dipole magnets on the beam parameters at the extraction point is studied for different orders and types of aberrations. Estimates of the contributions of the different types of aberrations to the extracted beam emittance are presented.
[en] The achievement of high density very-low energy spread electron beams requires a deep knowledge of this topic. For this purpose longitudinal and transverse beam relaxations are studied for two different sources, a thermo- and a photo-cathode. As a result a plasma parameter greater than 1 has been measured, that may potentially increase the efficiency of the electron cooling technique