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Some PSK Lattice Observations U. Wienands, April 23, 07. Coupling bumps B eam Sizes. SK5 & -5 mm bump. C 12 (BAR) Sunday 2pm. SKG1. Dispersion. Sizeable y upstream (SK5 bump!). Beam Sizes. @ LER SXM ß x ≈ 5.1 m, ß y ≈ 27 m ( ß y meas’d)
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Some PSK Lattice ObservationsU. Wienands, April 23, 07 • Coupling bumps • Beam Sizes
SK5 & -5 mm bump C12(BAR) Sunday 2pm
Dispersion • Sizeabley upstream (SK5 bump!)
Beam Sizes • @ LER SXM • ßx ≈ 5.1 m, ßy ≈ 27 m (ßy meas’d) • x ≈ 0.34 m, y ≈ 0.01 m (y upper limit, from meas.) • dp/p = 6.3E-4 • => in x, 0.4 mm for 24 nmr • => in y, 0.2 mm for 1.5 nmr
volume Major (x) Minor (y) Peak (x)
Analysis of data: • x,min ≈ 29 nmr (possible) • y,min ≈ 2.7 nmr (unlikely, but…)
IP beam sizes • Measurements: • ∑minor = 7.9 µm • ∑major = 150 µm • ß*x,HER = 24 cm, ß*x,LER = 60 cm • ß*y,HER = 9.7mm, ß*y,LER = 8.1mm • Use meas’d LER emitt, 50/1.5 nmr for HER, meas’d ß* to estimate ∑: • ∑x = 170 µm, ∑y = 6 µm (6.5 µm if ß*y=10 mm) • ∑x ok since dyn. ß reduces meas’t, • ∑y too small • ß*y,eff maybe higher => coupling issue (??)
BaBar Beam Sizes • What’s up with bunch length??
Conclusion • Fundamentally the new optics works • Lsp ≈ 5 at low currents, > 4.4 starting point. • Local C12(bar) looks ok. • We will need to address the SK5 coupling bump • With luck, SK5 & SKG1 make a closed wave • LER vertical emittance not yet really small • ∑minor measured is too big for beam sizes, ß*y • > may indicate local coupling issue