85520483
A superconductive undulator for the munich laser-plasma accelerator
Laser-plasma accelerators are expected to produce electron beams with bunch charges in the nano-Coulomb range with energies in the GeV range. By employing shortperiod superconductive undulators (e.g. [1]) this may be utilised for the generation of undulator radiation in the Xray regime with a compact laboratory-sized set up. In this contribution we report on the project of testing this concept at the Laser Wakefield Accelerator (LWFA) in Munich. A particular aim of this project is to push the superconductive undulator technology to shortest periods and highest on-axis fields at gap widths sufficiently large to reduce the impact of resistive wall wake fields on the electron beam. This might open a path to the generation of coherent radiation via the SASE process.
44202799
Construction and First Magnetic Field Test of a Superconducting Transversal Gradient Undulator for the Laser Wakefield Accelerator in Jena.
A superconducting transversal gradient undulator (TGU), tailored to the particular beam properties of the laser wakefield accelerator (LWFA) at the University of Jena, has been designed and constructed at KIT. This undulator in combination with a specialized beam transport line will be employed to produce undulator radiation with natural bandwidth despite the relatively large energy spread of the electrons (ΔE/E0 ∼ 10 %) produced by the LWFA. The fabrication of this undulator and first results of the magnetic field measurement are discussed in this paper.
55394694
Inductive Shimming of Superconductive Undulators - Preparations for a realistic test
The monochromaticity and intensity of synchrotron light emitted by undulators strongly depend on the undulator field quality. For the particular case of superconductive undulators it was shown recently that their field quality can be significantly improved by an array of coupled high temperature superconductor loops attached to the surface of the superconductive undulator. Local field errors induce currents in the coupled closed superconducting loops and, as a result, the hereby generated magnetic field minimises the field errors. In previous papers the concept was described theoretically and a proof-of-principle experiment was reported. This paper reports on a preparation experiment for the first quantitative measurement of the phase error reduction in a 13-period short model undulator equipped with a full-scale induction shimming system.
59470127
A YEAR'S EXPERIENCE WITH A SUPERCONDUCTING UNDULATOR IN THE STORAGE RING ANKA *
In March 2005 a superconductive undulator was installed in ANKA and since that time has been in operation [1]. The cryogen-free superconducting undulator was warmed up for one day one year later for routine maintainance of the cryocoolers. The results of the first ever beam tests of a superconducting undulator in a storage ring are summarized in this paper including the obtained spectra and the measurements on the heat load from the beam. The values obtained are so promising that a new undulator with improved performance will be built for ANKA and installed in two years from now.
124003158
Design of a Dispersive Beam Transport Line for the JETI Laser Wakefield Accelerators
125204951
A new concept for reducing phase errors in superconductive undulators: induction-shimming
Undulators are the most advanced sources for the generation of synchrotron radiation. The photons generated by a single electron add up coherently along the electron trajectory. In order to do so the oscillatory motion of the electron has to be in phase with the emitted photons along the whole undulator. Small magnetic errors can cause unwanted destructive interferences. In standard permanent magnet undulators the magnetic errors are reduced by applying shimming techniques. Superconductive undulators have higher magnetic fields than permanent magnet undulators but shimming is more complex. In this paper it is shown that coupled superconductive loops installed along the surface of the superconductive undulator coil can significantly reduce the destructive effect of the field errors. This new idea might allow the building of undulators with a superior field quality.
121019950
Search for a small-scale neutrino anisotropy with three years of IceCube data
The IceCube neutrino observatory built in the antarctic ice offers unique opportunities in studying high energy neutrino emission from Galactic and extragalactic sources. Detecting such neutrino emission could give valuable information about the origin of cosmic rays. Recently, first evidence for a diffuse astrophysical neutrino signal in the PeV range was found with IceCube. There is no clear point source signal yet, and advanced analysis methods are being developed in order to improve the sensitivity to point sources and resolve the diffuse signal into point sources. Other searches like a energy-dependent likelihood scan were already performed on IceCube data. In this paper, we report a complementary search for multiple neutrino point sources from three years of IceCube data, performing an autocorrelation test on the full sky. This analysis is aiming for various faint sources at unknown positions and energy spectra in the sky. The result obtained from this search is consistant with a background-only case and shows an underfluctuation. Here, we present limits using the ansatz of the small-scale anisotropy search.