TGM-Beamline at DELTA

Abstract

The former TGM3-beamline of BESSYI was rebuilt at the 1.5 GeV storage ring facility DELTA at the University of Dortmund, Germany. This dipole beamline provides synchrotron radiation between 6 and 200 eV for photoelectron spectroscopy and Fermi-surface-mapping experiments. The former beamline design was kept, especially the optical layout. The vacuum system was completely redesigned, except the mirror and slit chambers. For the beamlinesetup at DELTA, the focusing mirror is mounted inside the radiation wall shielding, therefore a motorisation of the mirror movements was necessary. The thermal load on the optical elements at DELTA is much higher than the previous load at BESSYI because of the higher electron beam energy in the storage ring. Therefore a watercooling of the first mirror had to be integrated and a complete new design of the chamber for the focusing mirror was necessary. In order to integrate the monochromator into the beamline control system, the monochromator control system had to be replaced. First commissioning of the beamline will be performed in 2006.

Signatures of different carbon bonds in graphene oxide from soft x-ray reflectometry

“…The photon flux at this point is typically~10 12 photons/s for a synchrotron ring current of 100 mA, a photon energy of 400 eV and a 40 μm exit slit width. [19] Figure 3b gives a schematic overview of the reflectometry set-up used in this work. The graphene samples were placed at the centre of a magnetization device in a multipurpose ultra-high vacuum chamber of 600 mm diameter.…”

Flemish Strings of Magnetic Solitons and a Nonthermal Fixed Point in a One-Dimensional Antiferromagnetic Spin-1 Bose Gas

“…Recently, a non-thermal fixed point (NTFP) [11,12,34,35] has attracted growing interest as a universal thermalization scenario in isolated quantum systems. It is expected to provide a unified framework of different nonequilibrium phenomena in diverse systems ranging from cosmology to cold atoms [34,35]. As illustrated in Fig.…”

“…In Ref. [72], a NTFP in a 1D Bose gas is theoretically discussed, but the dynamical scaling (1), which is regarded as a hallmark of a NTFP [34], is not confirmed. In Ref.…”

Boltzmann equations for preheating

“…While we calculate the collision terms directly from the operator algebra, we have written them in terms of the self-energies and Green's functions so as to make contact with approaches based on non-equilibrium quantum field theory (see, e.g., Refs. [56,57]). In this case, the collision terms can be associated with the absorptive cuts of the non-equilibrium self-energies, which can be calculated by means of the Kobes-Semenoff [77,78] cutting rules that generalize those of Cutkosky [79], and 't Hooft and Veltman [80].…”

“…[50][51][52] by means of the Schwinger-Keldysh closed-time-path [53,54] and Kadanoff-Baym [55] formalisms of non-equilibrium quantum field theory (see also Refs. [56,57]). Therein, the number density must be carefully defined [58], and the pair correlations can then be accounted for in the non-equilibrium Green's functions by working with coherent quasi-particle approximations [59][60][61] or directly in terms of the operator algebra by means of the so-called interaction-picture approach [62,63].…”