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20130225 Quad Scan Analysis

Previous quad scans took a lot of time and don't provide the clearest picture. During the previous quad scan on shift on the 20130222, the following procedure was used:

Name Samples Steps Range (um) Average Time Provides?
Quick vertical scan 10 5 20 44s vertical centring
Detailed horizontal scan 40 20 2000 11m33s horizontal centring and horizontal size
Nonlinear vertical scan 50 30 150 8m40s vertical size

  • Typically 25 minutes per magnet current with 5 minutes changing, minimising background again (post ip) and ensuring don't loose signal
  • 3A steps, 9 points measured

Despite increasing the chamber speed to 50um/s, the horizontal scan still takes the most time and with a typical uncertainty of +-10um on the horizontal size (fitting to be improved..) it's still not the most accurate.

  • The time for this whole process needs to be reduced
  • The horizontal uncertainty ideally needs to be less
  • Ideally, 2 or 3 vertical scans would be repeated at each current for statistics.


  • OTR images provide horizontal sizes with a lower uncertainty than the laser-wire scans and can be done much quicker at the end.
  • Use the OTR images for horizontal information and do only a small horizontal scan for centring.
  • Perform 2 non-linear scans at each location
  • Optimise non-linear scan points to reduced number of points required for the same uncertainty or even lower uncertainty

Physics WebpagesRHUL WebpagesCampus Connect • Royal Holloway, University of London, Egham, Surrey TW20 0EX; Tel/Fax +44 (0)1784 434455/437520

Topic revision: r1 - 25 Feb 2013 - LaurieNevay

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