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Beam spot size measurements

Beam spot size measurements. A. Fisher & W. Kozanecki See details in PEP-II e-logbook, 25 Apr 06 day shift. Single-beam & IP beam size measurements  scans at moderate currents (to minimize beam-beam effects) simultaneously measure beam sizes @ HER & LER SLM, interferometer & SXM

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Beam spot size measurements

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  1. Beam spot size measurements A. Fisher & W. Kozanecki See details in PEP-II e-logbook, 25 Apr 06 day shift • Single-beam & IP beam size measurements •  scans at moderate currents (to minimize beam-beam effects) • simultaneously measure beam sizes • @ HER & LER SLM, interferometer & SXM • both in collision and in single-beam mode • with (almost?) the same lattices as characterized on 21/22 Apr 06 • will then use R-matrices derived from MIA data of 21-22 Apr to estimate HER & LER IP beam sizes, using  measurements as a constraint • Calibration of HER SLM scale using local closed-orbit bump

  2. Beam conditions standard by-2, 1722 bunches I- / I+ = 535/230 mA (.31/.13 mA/b) 1 round of tune optimization in collision before beam-bean scans Data files: PHYSICS5_DATA [pep2.ip.witold.spr06]*25Apr [pep2.char.25apr06] (FJD, MS, JT, GY)  scans

  3. e+ only Stable collisions e- only Beam currents & luminosity current Lsp Hcurrent

  4. e+ only Stable collisions  SLM X interf Y SXM X SXM Y

  5. Stable collisions e+ only Stable collisions Stable collisions e- only e- only x-tilt & HER  SXM  HSLM X Hinterf Y

  6. Beam size measurement summary Spot size data: LUMSIZ_2B_25AprLER & HER dispersion: 21 Apr 06 characterization

  7. Data files: HSLM_XCALIB_2_25APRHSLM_YCALIB_1_25APR HER SLM calibration • Two steps • SLM response vs. knob: d centroid_x, y / d Knob_x, y • x: 0.840 y: 0.850 (d SLM / d knob) • knob calibration wrt BPMs using orbit fit • x: 0.952 y: 0.982 (d OrbFit / d kknob) Overall: x (y) measured / true = 0.882 (0.867) • Note that this vertical calibration applies to the HER SLM only, NOT to the corresponding interferometer

  8. Spares

  9. Bump closure & orbit fits at HER SLM for a 0.5mm bump

  10. SLM/interf off-diagonal response X scan: Y centroid Y scan: X centroid X scan: Y size Y scan: X size

  11. Dispersion at HER & LER SLM/SXM HER SLM LER SXM

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