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MD report: IP aperture scans

MD report: IP aperture scans. P. Grenier, W. Kozanecki & M. Weaver + S. Ecklund's watchful eyes!. MD goals Experimental procedure HER-only x & y scans + high-current extrapolation [LER only X & y scans] + high-current extrapolation. MD goals.

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MD report: IP aperture scans

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  1. MD report: IP aperture scans P. Grenier, W. Kozanecki & M. Weaver + S. Ecklund's watchful eyes! • MD goals • Experimental procedure • HER-only x & y scans + high-current extrapolation • [LER only X & y scans] + high-current extrapolation

  2. MD goals • Quantify Babar background sensitivity to IP x & y angles for • single beams (HER & LER separately, moderate currents) • collisions (moderate currents, then high currents) and determine the optimum angles (from the background viewpoint) • Cross-calibrate • LIPP & HIPP BPMs • Babar luminous & boost angles against support-tube (ST) BPMs • Determine LER IP angles  center of luminosity monitor • absolute angles (from ST BPMs) at moderate current • reference angles (from HIPP & LIPP), corrected for high-current operation

  3. Support-tube (ST) BPMHIPP BPMLIPP BPM Locations of the IP BPMs & neutron monitors Neutron_forw_1 Neutron_forw_2 Neutron_bckw_1 CsI 7

  4. (Intended)Measurement Sequence • Setup • colliding beams, offset by-2 patterns at 300 mA ea. • Single-beam scans: Babar on • HER • XP scan, then YP scan @ 300 mA, offset pattern • with XP & YP at optimum, raise IH as high as it will go, to measure current-dependence of support-tube (ST) - L/HIPP correlation • LER • XP scan, then YP scan @ 300 mA, offset pattern • with XP & YP at optimum, raise IL until ST BPMs saturated • Luminosity-monitor scans: Babar on • YP(e+) scan attempted; failed bec. IP Multiknob fbk not functional • Current-dependence of ST-L/HIPP correlation in collision • most likely different from single-beam (heat from both beams) • Background scans @ high current: XP(e-), YP(e+), XP(e+), YP(e-) • beam-beam tails behave diffferently from beam-gas

  5. Experimental procedure • Operating procedure: general • manual scans, CRR plots vs time • monitor angles with ST BPMs, LIPP/HIPP orbit fits & monitoring fbks • monitor temps & vacuum throughout the scans • trickle, Babar on (incl. DAQ, with background-enriched trigger) • Initial setup: colliding beams, offset patterns, trickle, Babar on • bunch patterns • LER: by-2, 300 mA, buckets 400-3400. BPM measdef @ bucket 3200 • HER: by-2, 300 mA, buckets 0-3000. BPM measdef @ bucket 200 • set initial IP angles based in May 2005 lumi-monitor settings (exc. XP-) • LER XP = 9.25 mrad (ST BPMS) YP = - 1.1 mrad (ST BPMs) • HER XP = -16.7 mrad (ST BPMS) YP = + 1.1 mrad (ST BPMs)

  6. YP_ST (e-) during XP scan HER-only scans: current- & angle history HER current XP_ST (e-) YP_ST (e-)

  7. HER-only scans: ST vs HIPP BPMs @ 300 mA XP (HIPP) vs. XP_ST XP (orbFit) vs. XP_ST YP (orbFit) vs. XP_ST YP (HIPP) vs. XP_ST

  8. HER-only XP scan (1a) Normalized to HER-only prediction TR-23 (EMC) x 2.6 x 1.7 BW dmd, normalized E-collim (PR12 9082) x 2.3

  9. PR02 VP8020 HER-only XP scan (1b) PR02 VP7032 CsI 3054 PR02 VP8029

  10. HER-only XP scan (2a) SVT occpcy,  = 180 (W) SVT occpcy,  = 0 (E) x 2.7 x 3.6 neutron fwd_1 x 11

  11. PR02 VP8027 HER-only XP scan (2b) PR02 VP7042 PR02 VP7034 PR02 VGH_8027

  12. HER-only YP scan (1a) Xcoll PR12 7102 Ycoll PR12 8072 CSi7052 neutron bwd_1

  13. HER-only YP scan (1b) SVT occpcy,  = 0 (E) SVT occpcy,  = 180 (W)

  14. PR02 VP8027 HER-only YP scan (1c) PR02 VP8020 PR02 VGH_8027

  15. HER-only YP scan (2) TR-23 (EMC) BW dmd, normalized neutron fwd_1 Normalized to HER-only prediction

  16. HER-only YP scan (3) neutron fwd_2 CSi3054 PR02 VP8024

  17. High-current extrapolation: HER-only HER current XP_ST (e-) YP_ST (e-)

  18. HER-only YP scan (4) E-collim (PR12 9082) PR02 VP8029

  19. High-current extrapolation (HER-only): ST vs HIPP XP (HIPP) XP (HIPP) vs. XP_ST (e+) YP (HIPP) vs. YP_ST (e+)

  20. High-current extrapolation (HER-only) (1a) BW dmd, normalized Dynamic pressure E-collim (PR12 9082) TR-23 (EMC)

  21. High-current extrapolation (HER-only): pressure sampling Thermal outgassing

  22. High-current extrapolation (LER-only): angles vs. I LER current YP_ST (e+) XP_ST (e+)

  23. High-current extrapolation (LER-only): ST vs. LIPP XP (YIPP) YP (LIPP) YP_ST (e+) XP_ST (e+)

  24. To do… • Document usable scan ranges • first pass (PG) @ http://www.slac.stanford.edu/BFROOT/www/Detector/Backgrounds/ApertureScan-05Mar07.html • supply tables of XP(LER/HER, ST BPMS) vs. time stamps • Detailed analysis for each subdetector • SVT occupancies, DCH current + occupancies, DIRC scalers & currents - use normalized quantities (2004) wherever possible • clean up data sets (e.g. remove spikes associated with LER LFB problems, with knob turning, etc) • how well does the 'family' concept hold? • Analyse temperatures • Analyse vacuum signatures Volunteers needed!

  25. Summary (preliminary!) • Background sensitivity to single-beam aperture scans @ 300 mA • significant, may explain part of the discrepancy w/ Jan '04 norm'lztn; • is different, in both magnitude & optimum, for different subdetectors. The overall background optimum is incompatible with the SR load, at least in the HER (LER tba) • There may be subdetectors 'families' that depend on X/Y, HER/LER; within one scan, several sources are at work, depending on the direction of SR fans & local aperture restrictions. • Consistency between ST BPM's & LIPP/HIPP • much improved since run 5 • degrades as current increases, esp. for LER XP • Luminosity monitor scan • could not be completed for lack of working IPO Multiknob feedback. Can the fast dither play the same role? We need to know the center! • may yield LER IP angles different from the single-beam optimum. • No reason to believe that this single-beam optimum will coincide with that for beam-beam tails: need to explore XP & YP optimization on both L and backgrounds under physics conditions!

  26. Appendix: CRR plot files & data sets • PEP-II e-log: 5 March 2007 day + swing shift See also http://www.slac.stanford.edu/BFROOT/www/Detector/Backgrounds/ApertureScan-05Mar07.html for scan times & ranges • CRR button files • BBR_BKG_LERIPORB.btn • BBR_BKG_HERIPORB.btn • BBR_ALL_BKG.btn • All data in PHYSICS_DATA:[pep2.char.05mar07]

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