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Recycler 1.75 GHz Schottky Detectors Calibration

This study focuses on the calibration of Schottky detectors for emittance measurements using scrapers in the Recycler department. Three methods of emittance calculation are explored, including the 95% method, RMS method, and beam profile reconstruction. The results show consistent answers and highlight the importance of separated tunes for accurate calibration.

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Recycler 1.75 GHz Schottky Detectors Calibration

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  1. Recycler 1.75 GHz Schottky Detectors Calibration Martin Hu Recycler Department

  2. Emittance Measurement with Scrapers • Step beam loss versus change in scraper position is recorded (P141). • Schottky power • Three methods of emittance calculation: • The 95% method. • The RMS method. • Beam profile reconstruction.

  3. Emittance Measurement with Scrapers End of scrape DCCT in Recycler Start of loss X = Calibrated scraper position in mm

  4. Emittance measurement with scrapers • A Flying wire, IPM or Multi-wires measure the density profile of beam directly • Measurements with scrapers require analysis because these measure many turns of beam x’(s) scraper x(s)

  5. Coordinate transformation x’(s) y(x(s), x’(s)) R x(s) x(s)

  6. Method 1: The 95% Method Ibeam is 95% of initial End of scrape

  7. Method 2: The RMS Method

  8. Method 3: Profile Reconstruction Given the scraper position and the beam current remaining, the projection of beam density on a transverse axis is: for a certain bin centered at Y. scraper position; beam current (number of particles). This integral is approximated by a sum and calculated for each bin. The result of projected beam density on a transverse axis is then plotted and fitted to a Gaussian. This method is informative but not always useful for the calibration of a Schottky detector.

  9. Scraping both planes with one scraper – real data

  10. Evidence of betatron coupling: oscillations due to a horizontal kick

  11. Reconstructed profile with small tune separation

  12. Simulation of scraping an uncoupled beamsimultaneously with a horizontal and a vertical jaw Scraping in 2-D Scraping in 4-D 1-D density function from 2-D scraping 1-D density function from 4-D scraping

  13. Reconstructed profile with large tune separation

  14. Noise problem for the horizontal Schottky related to MI beam intensity

  15. Conclusion • Calibration accuracy is limited by MI beam related noise for the horizontal 1.75 GHz pickups • All three methods give consistent answers • Calibration of the Schottky detectors should always be made with separated tunes • Beta function at the vertical scraper has been confirmed with BPM TBT

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