Keyword: polarization
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MOPB050 Characterization of SRF Materials at the TRIUMF muSR Facility TRIUMF, SRF, positron, vacuum 205
 
  • R.E. Laxdal, T.J. Buck, T. Junginger, P. Kolb, Y.Y. Ma, L. Yang, Z.Y. Yao
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • S.H. Abidi
    University of Toronto, Toronto, Ontario, Canada
  • R. Kiefl
    UBC & TRIUMF, Vancouver, British Columbia, Canada
 
  MuSR is a powerful tool to probe local magnetism and hence can be used to diagnose flux penetration in Type-II superconductors. Samples produced at TRIUMF and with collaborators in both coin shaped and ellipsoidal geometries have been characterized by applying either transverse or parallel fields between 0 and 300mT and measuring flux entry as a function of applied field. Samples include Nb treated in standard ways including forming, chemistry, and heat treatments. Further, Nb samples have been doped with Nitrogen and coated with a 2 micron layer of Nb3Sn by collaborators from FNAL and Cornell respectively and measured in three field/geometry configurations. Analysis of the method in particular the effects of geometry and the role of pinning will be presented. Results of the measurements will be presented.  
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MOPB051 Muon Spin Rotation on Treated Nb Samples in Parallel Field Geometry cavity, SRF, detector, niobium 210
 
  • S. Gheidi
    UBC, Vancouver, B.C., Canada
  • T.J. Buck, T. Junginger, R.E. Laxdal, G. Morris
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • M. Dehn
    TUM/Physik, Garching bei München, Germany
  • R. Kiefl
    UBC & TRIUMF, Vancouver, British Columbia, Canada
 
  MuSR is a powerful tool to probe local magnetism and hence can be used to diagnose the entry of magnetic flux in superconductors. First measurements on SRF samples were done with an external DC field applied perpendicular to the sample1 (transverse geometry) with the muons applied to the sample face. Here the results are strongly impacted by demagnetization, pinning strength and edge effects. A new spectrometer has been developed to allow sample testing with a field varying from 0 to 300mT applied along the sample face (parallel geometry) analogous to rf fields in SRF resonators. The geometry is characterized by a small demagnetization factor reducing the impact of pinning and edge effects on field of first flux entry. The beamline installation and first results comparing transverse and parallel results will be presented.
1 Grassellino et al. Muon spin rotation studies of niobium for superconducting rf applications.
Phys. Rev. ST Accel. Beams, 16:062002, Jun 2013.
 
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THPB017 A Higher Harmonic Cavity at 800 MHz for HL-LHC cavity, HOM, cryomodule, simulation 1100
 
  • T. Roggen, P. Baudrenghien, R. Calaga
    CERN, Geneva, Switzerland
 
  Funding: Marie Curie action: Grant agreement PCOFUND-GA-2010-267194
A superconducting 800 MHz second harmonic system is proposed for HL-LHC. It serves as a cure for beam instabilities with high beam currents by improving Landau damping and will allow for bunch profile manipulation. This can potentially help to reduce intra-beam-scattering, beam induced heating and e-cloud effects, pile-up density in the detectors and beam losses. An overview of the 800 MHz cavity design and RF power requirements is given. In particular the design parameters of the cavity shape and HOM couplers are described. Some other aspects such as RF power requirements and cryomodule layout are also addressed.
 
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