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Measurements in PS @ 2GeV (Analysis is ongoing!!!)

Measurements in PS @ 2GeV (Analysis is ongoing!!!). Space Charge Meeting, 1 Dec 2011. Qy. 0. 5. 0.25. 0. 0. 0. 5. 0.25. Qx. Working point scan. Dynamic tune scan Losses & Tune measurements Large emittance, low-intensity beam Chromaticity not corrected (x x~-0.8, x y ~-1 )

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Measurements in PS @ 2GeV (Analysis is ongoing!!!)

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  1. Measurements in PS @ 2GeV (Analysis is ongoing!!!) Space Charge Meeting, 1 Dec 2011

  2. Qy 0. 5 0.25 0 0 0. 5 0.25 Qx Working point scan • Dynamic tune scan • Losses & Tune measurements • Large emittance, low-intensity beam • Chromaticity not corrected (xx~-0.8, xy~-1) → efforts by Alex to find working point w. PFW to correct 1stand 2nd order Chromaticity, ONGOING)

  3. Parameters • LIU_V1_SpaceCharge: (LHC_Hi_Bright_rebuket in PSB) • Nb~70e10 • Ex*~Ey*~2um • Bunch length(4s)=55ns , parabolic bunch • (bunch compression by increasing RF voltage) • dp/p~1.21e-3 • Space Charge tune shift (H,V): -0.21; -0.29 • Qx=6.20, Qv= scan from 6.21 to 6.38 • xx=-0.8, xv=-1

  4. Losses and Transverse emittance evolution vs. Qv Qv Tails in the vertical profiles for Qv>0.30 • Large error-bars in WireScanners measurements (need to refine analysis) • Tomoscope data still to be analyzed • Important losses @ Qv=0.28-0.29

  5. Losses on the 0.25 line • Apparently no blow-up or profile modification • Need careful analysis of profiles! • It happens: • between C784-995 --> Qy=.268-.29 for short bunch (DQy=-0.27) • between C677-816 --> Qy=.257-.27 for long bunch (DQy=-0.175) ms Quick check with low-intensity beam:→ small change in loss slope for Qv=6.25

  6. Example of tails in vertical profile a.u. 320 ms 1320 ms Qv=6.32 Qx=6.20 • Attempt to fit it: • 2 Gaussians (thanks Ana, BI!) • Levy distribution (thanks Michel!) mm

  7. Levy-Student distribution • Material from Michel, Simone and…Google!  • Developed for finance, where non-Gaussian tails are important • Parametrization (a=2 → Gaussian, a=1 → Cauchy) • N. Cufaro Petroni, S. De Martino, S. De Siena, F. Illuminati, Lévy-Student distributions for halos in accelerator beams, Phys. Rev. E 72, 066502 (2005)

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