arXiv subjects
Publications and source records attributed to N. Golubeva.
This document presents an overview of LUXE (Laser Und XFEL Experiment), an experiment that will combine the high-quality and high-energy electron beam of the European XFEL with a high-intensity laser, to explore the uncharted terrain of strong-field quantum electrodynamics. The scientific case, facility, and detector setup are presented together with an overview of the foreseen timeline and expected capital costs.
This Technical Design Report presents a detailed description of all aspects of the LUXE (Laser Und XFEL Experiment), an experiment that will combine the high-quality and high-energy electron beam of the European XFEL with a high-intensity laser, to explore the uncharted terrain of strong-field quantum electrodynamics characterised by both high energy and high intensity, reaching the Schwinger field and beyond. The further implications for the search of physics beyond the Standard Model are also discussed.
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.
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.
Our objective in this paper is to describe an invariant optimality criterion and then apply it to the procedure of emittance measurement in periodic beam transport channels.
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.
The aim of the FLASH linac is to create electron bunches of small transverse emittance and high current for the free electron laser facility FLASH at DESY. Available operational experience indicates that in order to optimize SASE signal at different wavelengths or to fine-tune the FEL wavelength, empirical adjustment of the machine parameters is required and, therefore, the sensitivity of the beamline to small changes in the beam energy and in the magnet settings becomes one of the important issues which affects both, the final performance and the reproducibility of the results after breaks in operation. In this article the transverse optics of the FLASH beamline with low sensitivity to changes in beam energy and quadrupole settings is presented. This optics is in operation since spring 2006 and has shown a superior performance with respect to the previous setup of the transverse focusing.
In this article we give an overview of the the post-linac collimation system for the European X-Ray Free-Electron Laser (XFEL) Facility with main emphasis on lattice and optics design.
In this article we introduce a group-theoretical point of view for the design of magnetic optical achromats based on symmetry. As examples we use two-cell repetitive achromats and four-cell achromats employing mirror symmetry.
Though a straight drift-quadrupole system can not be made an achromat, there exists an example of a bend-free drift-quadrupole system which can transport certain incoming beam ellipses without introducing first-order chromatic distortions. In this paper we show that such a possibility is not a rare special case, but a general property. For every drift-quadrupole system there exists an unique set of Twiss parameters, which will be transported through that system without first order chromatic distortions. Moreover, we prove that at the same time these Twiss parameters minimize the absolute values of the system chromaticities and also bring the second order effect of the betatron oscillations on the longitudinal dynamics to the minimal possible value.
The problem of errors, arising due to finite BPM resolution, in the difference orbit parameters, which are found as a least squares fit to the BPM data, is one of the standard problems of the accelerator physics. In this article we present a "dynamical point of view" on this problem, which allows us to describe properties of the BPM measurement system in terms of the usual accelerator physics concepts of emittance and betatron functions.
In this article we discuss the usage of tilted multipoles for correction of chromatic aberrations in the design of the beam switchyard arc at the European X-Ray Free-Electron Laser (XFEL) Facility.
The option to install two injectors is foreseen at the European XFEL Facility. The injectors will be located on top of each other in the same building, both with the offset of 2.75 m with respect to the main linac axis. The translation system (dogleg) from the injector axis to the main linac axis has to fulfill very tight requirements of the chromatic properties, because the energy chirp required for the downstream bunch length compression in magnetic chicanes will be created upstream in the injector linac. In this paper we present such an large energy acceptance dogleg and discuss the optical principles which form the basis of its design.
We investigate the efficiency of systems of molecular motors operating at maximum power. We consider two models of kinesin motors on a microtubule: for both the simplified and the detailed model, we find that the many-body exclusion effect enhances the efficiency at maximum power of the many-motor system, with respect to the single motor case. Remarkably, we find that this effect occurs in a limited region of the system parameters, compatible with the biologically relevant range.
We show that the 1D Courant-Snyder theory can be considered as a partial case of the multidimensional theory of coupled particle beams with equal eigenemittances.
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.
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.
We consider a molecular machine described as a Brownian particle diffusing in a tilted periodic potential. We evaluate the absorbed and released power of the machine as a function of the applied molecular and chemical forces, by using the fact that the times for completing a cycle in the forward and the backward direction have the same distribution, and that the ratio of the corresponding splitting probabilities can be simply expressed as a function of the applied force. We explicitly evaluate the efficiency at maximum power for a simple sawtooth potential. We also obtain the efficiency at maximum power for a broad class of 2-D models of a Brownian machine and find that loosely coupled machines operate with a smaller efficiency at maximum power than their strongly coupled counterparts.