Suchergebnisse

5 pages, 6 figures. v2: minor updates after referee comments, matches published version in IEEE ; The axion is a hypothetical particle which is a candidate for cold dark matter. Haloscope experiments directly search for these particles in strong magnetic fields with RF cavities as detectors. The Relic Axion Detector Exploratory Setup (RADES) at CERN in particular is searching for axion dark matter in a mass range above 30 $\mu$eV. The figure of merit of our detector depends linearly on the quality factor of the cavity and therefore we are researching the possibility of coating our cavities with different superconducting materials to increase the quality factor. Since the experiment operates in strong magnetic fields of 11 T and more, superconductors with high critical magnetic fields are necessary. Suitable materials for this application are for example REBa$_2$Cu$_3$O$_{7-x}$, Nb$_3$Sn or NbN. We designed a microwave cavity which resonates at around 9~GHz, with a geometry optimized to facilitate superconducting coating and designed to fit in the bore of available high-field accelerator magnets at CERN. Several prototypes of this cavity were coated with different superconducting materials, employing different coating techniques. These prototypes were characterized in strong magnetic fields at 4.2 K. ; This project has received funding from the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871 (ARIES-TNA). BD and JG acknowledge funding through the European Research Council under grant ERC-2018-StG-802836 (AxScale). We also acknowledge funding via the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under project PID2019- 108122GB-C33, and the grant FPI BES-2017-079787 (under project FPA2016-76978-C3-2-P). Furthermore we acknowledge support from SuMaTe RTI2018-095853-B-C21 from MICINN co-financed by the European Regional Development Fund, Center of Excellence award Severo Ochoa CEX2019- 000917-S and CERN under Grant ...

The matter - anti matter asymmetry observed in the universe today still lacks a quantitative explanation. One possibility that could contribute to the observed state could be a violation of the combined Charge-, Partiy- and Timesymmetries (CPT). To test if the CPT symmetry is broken the ASACUSA collaboration (Atomic Spectroscopy And Collisions Using Slow Antiprotons) at the CERN AD (Antiproton Decelerator) tries to produce a low temperature beam of antihydrogen - the most simple atomic system built only of anti particles. The ground state hyperfine splitting of hydrogen is one of the most precisely determined quantities in physics. Therefore it follows naturally to test CPT invariance by comparing the ground state hyperfine splitting of hydrogen and antihydrogen at zero B field. This contribution will focus on presenting the current state of the fully assembled spectroscopy beamline, including a field-ioniser chamber, a strip-line resonator microwave cavity, a super conducting sextupole magnet and a detector for counting antihydrogen annihilations. We will put a spotlight on the performance of the beamline and on the detection part of the spectrometer. Our spectroscopy apparatus was tested with a beam of cold hydrogen and these tests lead to a measurement of the GS-HFS of hydrogen whose precision is in good agreement with simulation. The newly developed detector is composed of a position sensitive Bismutgermanat (BGO) disc in the centre and a two layer hodoscope made of plastic scintillators that is read via silicon photo multipliers (SiPM) with self developed frontend electronics. In addition, our first preliminary results of the detector performance with the fully assembled beamline from the 2014 beamtime at CERN are discussed. ; Grant-in-Aid for Specially Promoted Research (No. 24000008) of the Japan Society for the Promotion of Science (JSPS), and Pioneering Project of RIKEN, European Research Council under European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement (291242), the ...