Straightening of superconducting HERA dipoles for the any-light-particle-search experiment ALPS II

At DESY the ALPS II experiment is being installed in the HERA tunnel to search for axion like particles. A laser beam will be injected into the magnetic field of a string of superconducting (s.c.) dipole magnets, available from the HERA proton storage ring, to produce axion like particles. After passing a light tight wall, the ALPs can reconvert into photons in a second string of HERA s.c. dipoles. The sensitivity of the experiment will be increased by two mode-matched optical cavities before and behind the wall. The dipoles for the HERA storage ring are curved, suited for stored proton beam. However, the curvature of the magnets limits the aperture and hence the performance of theoptical resonators beyond a certain length. As the sensitivity of the search scales with the length of the magnetic field, the aperture for the optical resonators inside the HERA dipoles was increased by straightening the curved magnet yoke. The procedure of straightening the s.c. HERA dipoles is described in this report

Straightening of Superconducting HERA Dipoles for the Any-Light-Particle-Search Experiment ALPS II

At DESY the ALPS II experiment is being installed in the HERA tunnel to search for axion like particles (ALPs). A laser beam will be injected into a string of superconducting HERA dipole magnets, to produce ALPs. After passing a light tight wall, the ALPs can reconvert into photons in a second string of HERA dipoles.The sensitivity of the experiment will be increased by two mode-matched optical cavities before and behind the wall. The curvature of the magnets limits the performance of the optical resonators, Therefore the aperture for the optical resonators inside the HERA dipoles was increased by straightening the curved magnet yoke. The procedure of straightening the HERA dipoles is described in this report

Results of the Magnetic Measurements of the Superconducting Magnets for the European XFEL

A new linear accelerator, i.e., the European X-ray Free-Electron Laser (XFEL), is under construction at DESY in Hamburg. The construction started in early 2009, and the commissioning is planned for 2016. The design energy of the electron beam is 17.5 GeV (0.05-4.7 nm wavelength), and more than 27000 flashes/s are expected. The accelerator contains 102 cryomodules equipped with a string of eight superconducting RF cavities and one superconducting magnet package. Each magnet consists of two cos -θ-type correction dipoles, horizontal and vertical deflecting. They are glued onto the surface of the beam pipe and are surrounded by a superferric quadrupole magnet. The package is mounted inside of a compact stainless steel vessel with a length of 30 cm and a diameter of 20 cm. Each package and current lead assembly was tested separately at room temperature and together at 2 K in a dedicated superfluid helium cryostat at DESY. A summary of the results is reported here. During the cold test, special emphasis was given to hysteresis and persistent current effects, as the operating current varies from very low currents at the beginning of the accelerator to the full design current 50 A at the end