Relations between Projected Emittances and Eigenemittances

We give necessary and sufficient conditions that two sets of positive real numbers must satisfy in order to be realizable as eigenemittances and projected emittances of a beam matrix. The information provided by these conditions sets limits on what one can to achieve when designing a beam line to perform advanced emittance manipulations.Comment: 3 pages, IPAC1

Invariant Criterion for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections

We introduce and give examples of applications of an optimality criterion which can be used for the design and comparison of multiple beam profile emittance and Twiss parameters measurement sections and which is independent from the position of the reconstruction point.Comment: 3 pages, IPAC1

Possibilities for reduction of transverse projected emittances by partial removal of transverse to longitudinal beam correlations

We show that if in the particle beam there are linear correlations between energy of particles and their transverse positions and momenta (linear beam dispersions), then the transverse projected emittances always can be reduced by letting the beam to pass through magnetostatic system with specially chosen nonzero lattice dispersions. The maximum possible reduction of the transverse projected emittances occurs when all beam dispersions are zeroed, and the values of the lattice dispersions required for that are completely defined by the values of the beam dispersions and the beam rms energy spread and are independent from any other second-order central beam moments. Besides that, we prove that, alternatively, one can also use the lattice dispersions to remove linear correlations between longitudinal positions of particles and their transverse coordinates (linear beam tilts), but in this situation solution for the lattice dispersions is nonunique and the reduction of the transverse projected emittances is not guaranteed.Comment: 13 pages, 2 figure

Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell

Using the group-theoretical point of view we study in this paper second and third order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell and compare these achromats with repetitive achromats designed without internal cell symmetries taken into account.Comment: 3 pages, IPAC 201

Third-Order Apochromatic Drift-Quadrupole Beamline

In this paper we present the design of a straight drift-quadrupole system which can transport certain beam ellipses (apochromatic beam ellipses) without influence of the second and of the third order chromatic and geometric aberrations of the beamline transfer map.Comment: 3 pages, IPAC 201

Understanding the dynamic momentum aperture of the Advanced Light Source

The lifetime of a light source with small emittance like the Advanced Light Source (ALS) is usually limited by the momentum acceptance of the ring. Large momentum acceptances are reached by providing enough RF voltage and by avoiding a degradation of the dynamic momentum aperture. At the ALS the size of the momentum acceptance depends strongly on the transverse dynamics. It is very sensitive to machine conditions such as the tunes and chromaticities since depending on those conditions the Touschek scattered particles explore different resonance regions in the phase space. In this paper we show that by using a single-turn ’pinger’ magnet together with turn-byturn beam position monitors (BPM) one can identify the cause of a reduction in momentum acceptance and take steps to improve the acceptance

LAYOUT AND OPTICS OF THE DUMP LINE AT THE EUROPEAN XFEL

Abstract The purpose of the optical system, which we call the dump line, is not simply the transport of the beam to the beam dump. It is an essential part of the beam switchyard which provides the possibility to distribute electron bunches of one beam pulse to different FEL beam lines, allowing a flexible selection of the bunch pattern at each FEL experiment. In this paper we describe the final layout of this optical system as it is now under construction

Global beta-beating compensation of the ALS W16 wiggler

The W16 wiggler is the first wiggler and highest field insertion device to be installed in the ALS storage ring. When the gaps of the W16 wiggler are closed, the vertical tune increases by 0.065 and the vertical beta function is distorted by up to {+-}37%. There are 48 quadrupoles in the ring whose fields can be adjusted individually to restore the tunes and partially compensate the beta-beating. In order to adjust the quadrupole field strengths to accurately compensate the focusing, it is necessary to have a method to precisely determine the beta-beating. In this paper we compare measurements of the induced beta-beating using two methods: measuring the tune dependence on quadrupole field strength and fitting a lattice model with measured response matrices. The fitted model also allows us to predict quadrupole field strengths that will best compensate the beta beating. These quadrupole field strengths are then applied and the resultant beta-beating is measured