Volker Tympel

Planar hybrid superconductor-normal metal-superconductor thin film junctions based on BaFe1.8Co0.2As2

Abstract To investigate the transport properties of iron based superconductors, we prepared planar hybrid superconductor-normal metal-superconductor (SNS’) thin film junctions with BaFe 1.8 Co 0.2 As 2 as base electrode. As counter electrode we used a lead indium alloy, while the normal metal layer was formed by thin gold films. The junction design allows us to characterize the electrodes as well as the junction itself. Temperature dependent Andreev reflection studies of the junction show gap-like features but were also strongly influenced by the properties of the electrodes.

Preparation of hybrid Josephson junctions on Co-doped Ba-122 single crystals

In this paper we present a method for processing a hybrid Josephson junction on Co-doped (Ba-122) single crystals with a thin film Pb-counter electrode and a barrier layer of . This includes the leveling and polishing of the crystals and structuring them with thin film techniques such as photo lithography, sputtering and ion beam etching. The junctions show hysteretical resistively and capacitively shunted junction-like I?V characteristics with an -product of about 800 .

A Cryogenic Current Comparators (CCC) Customized for FAIR-Project

The principle of non-destructive measurement of ion beams by detection of the azimuthal magnetic field, using low temperature Superconducting Quantum Interference Device (SQUID) sensors, has been established at GSI already in the mid 90s. After more recent developments at Jena, GSI and CERN, a CCC was installed in the CERN Antiproton Decelerator (AD) and is operated there routinely as the first stand-alone CCC system. For the Facility for Antiproton and Ion Research (FAIR) a new version of the CCC with eXtended Dimensions (CCC-XD) especially with a larger inner diameter and adapted parameters was constructed and first lab tests have already been performed. In parallel, a concept for a dedicated UHV beamline cryostat has been worked out. The CCC-XD system together with the new cryostat will be ready for testing in the CRYRING at GSI before the end of 2018. In this contribution, experimental results for the resolution, frequency range, slew rate and pulse-signal obtained by electrical laboratory measurements with the CCC-XD are presented.

Physical Society of Japan : Superconducting beam charge monitors for antiproton storage rings

Institute for Solid State Physics, Friedrich Schiller University, D-07743 Jena, Germany 1 Institute for Solid State Physics, Friedrich Schiller University, D-07743 Jena, Germany 2 Institute for Optics and Quantum Electronics, Friedrich Schiller University, D-07743 Jena, Germany 3 Helmholtz Institute Jena, D-07743 Jena, Germany 4 GSI Helmholtz Center for Heavy Ion Research, D-64291 Darmstadt, Germany 5 The Cockcroft Institute, University of Liverpool, Daresbury, Cheshire WA4 4AD, U.K 6 CERN European Organization for Nuclear Research, CH-1211 Geneva, Switzerland

Optimization Studies for an Advanced Cryogenic Current Comparator (CCC) System for FAIR

After successful tests with the GSI-CCC prototype, measuring beam intensities down to 2 nA at a bandwidth of 2 kHz, a new advanced Cryogenic Current Comparator system with extended geometry (CCC-XD) is under development. This system will be installed in the upcoming Cryring facility for further optimization, beam diagnostics and as an additional instrument for physics experiments. After the test phase in Cryring it is foreseen to build four additional CCC units for FAIR, where they will be installed in the HEBT lines and in the Collector Ring (CR). A universal cryostat has been designed to cope with the various boundary conditions at FAIR and at the same time to allow for uncomplicated access to the inner components. To realize this compact cryostat, the size of the superconducting magnetic shielding has to be minimized as well, without affecting its field attenuation properties. Hence detailed FEM simulations were performed to optimize the attenuation factor by variation of geometrical parameters of the shield. The beam tests results with the GSI-CCC prototype, and the developments for FAIR, as well as the results of simulation for magnetic shield optimization are presented.