Author: Federmann, S.
Paper Title Page
WEPPD072 Frequency Fine-tuning of a Spin-flip Cavity for Antihydrogen Atoms 2690
  • S. Federmann, F. Caspers, E. Mahner
    CERN, Geneva, Switzerland
  • B. Juhasz, E. Widmann
    SMI, Vienna, Austria
  As part of the ASACUSA collaboration physics program a spin-flip cavity for measurements of the ground-state hyperfine transition frequency of anti-hydrogen atoms is needed. The purpose of the cavity is to excite anti-hydrogen atoms depending on their polarisation by a microwave field operating at 1.42 GHz. The delicacy of designing such a cavity lies in achieving and maintaining the required properties of this field over a large aperture of 10cm and for a long period of time (required amplitude stability is 1% within 12h). The present paper presents the frequency fine tuning techniques to obtain the desired centre frequency of 1.42 GHz with a Q value below 500 as well as the tuning circuit used for the frequency sweep over the desired bandwidth of 6 MHz.  
THPPC023 RF Loads for Energy Recovery 3326
  • S. Federmann, M. Betz, F. Caspers
    CERN, Geneva, Switzerland
  Different conceptional designs for RF high power loads are presented. One concept implies the use of solid state rectifier modules for direct RF to DC conversion with efficiencies beyond 80%. In addition, robust metallic low-Q resonant structures, capable of operating at high temperatures (>150 ̊C) are discussed. Another design deals with a very high temperature (up to 800 ̊C) air cooled load using a ceramic foam block inside a metal enclosure. This porous ceramic block is the actual microwave absorber and is not brazed to the metallic enclosure.