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Title: Field of first magnetic flux entry and pinning strength of superconductors for rf application measured with muon spin rotation

Here, the performance of superconducting radiofrequency (SRF) cavities used for particle accelerators depends on two characteristic material parameters: field of first flux entry H entry and pinning strength. The former sets the limit for the maximum achievable accelerating gradient, while the latter determines how efficiently flux can be expelled related to the maximum achievable quality factor. In this paper, a method based on muon spin rotation (μSR) is developed to probe these parameters on samples. It combines measurements from two different spectrometers, one being specifically built for these studies and samples of different geometries. It is found that annealing at 1400°C virtually eliminates all pinning. Such an annealed substrate is ideally suited to measure H entry of layered superconductors, which might enable accelerating gradients beyond bulk niobium technology.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [2] ;  [5] ;  [6] ;  [7] ;  [5] ;  [4] ;  [8]
  1. Lancaster Univ., Lancaster (United Kingdom); Cockcroft Institute, Warrington (United Kingdom)
  2. Univ. of Toronto, Toronto, ON (Canada)
  3. Univ. of Waterloo, Waterloo, ON (Canada)
  4. Univ. of British Columbia, Vancouver, BC (Canada)
  5. Univ. of British Columbia, Vancouver, BC (Canada); TRIUMF Canada's National Lab. for Particle and Nuclear Physics, Vancouver, BC (Canada)
  6. Brookhaven National Lab. (BNL), Upton, NY (United States)
  7. Univ. of Victoria, Victoria, BC (Canada); TRIUMF Canada's National Lab. for Particle and Nuclear Physics, Vancouver, BC (Canada)
  8. TRIUMF Canada's National Lab. for Particle and Nuclear Physics, Vancouver, BC (Canada)
Publication Date:
Report Number(s):
BNL-204653-2018-JAAM
Journal ID: ISSN 2469-9888; PRABCJ
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Physical Review Accelerators and Beams
Additional Journal Information:
Journal Volume: 21; Journal Issue: 3; Journal ID: ISSN 2469-9888
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS
OSTI Identifier:
1438430