Status and Plan for the PEP-II Lattices Yunhai Cai For Optics Task Force May 2, 2007

Luminosity Franz-Josef Decker Green: 1-Aug-2006 to 17-Aug-2006 Yellow: 1-Apr-2007 to 19-Apr-2007 Red: 20-Apr-2007 to 26-Apr-2007 (First week of PSK) Blue: 26-Apr-2007 to 1-May-2007 Franz-Josef Decker

Completed Tasks (I) Prepare implementation of the new lattice with permanent skew quadrupoles Build and measure magnets (FJ-D) Generate and double check the magnet knob (FJ-D, YY, YN) Prepare the online design lattice (GY,YY) Prepare the IP orbit bumps (YN,HS) Improve the turn-by-turn measurement from the beam position monitor Quantify and highlight the problem (YY,YC) Find work around: more bunch charge and calibration with bunch train (FJ-D,WW,UW)

Completed Tasks (II) April 19-23, 2007 Commission the new lattice in chronicle sequence: Install PSK (FJ-D) Store positron beam and initial tuning (Cap Sigma y = 14 microns) (FJ-D,GY) Build MIA models (YY) Beta beating and coupling correction with SK1, SK1L (-9,4.5 mrad, minus sign?) (GY, YY, YC) Full MIA correction including bumps (FJ-D,GY,YY,YC) Vertical dispersion correction with bumps (FJ-D, YC) Global coupling correction with bumps (FJ-D, YC) IP MIA coupling correction (25% in) (FJ-D, YY) Reach Lsp = 5 at low currents (MS, WW) Beta beating correction with QF2L (-0.26%) (FJ-D,YC)

Beta Beatings in Horizontal Plane First look After SK1, SK1L, and QF2L tweaks, dispersion and coupling corrections

Beta Beating in the Vertical Plane First look After SK1, SK1L, and QF2L tweaks, dispersion and coupling corrections

Couplings First look After SK1, SK1L, and QF2L tweaks, dispersion and coupling corrections

Beam-Beam Scans First look After SK1, SK1L, and QF2L tweaks, dispersion and coupling corrections

Vertical Dispersions

Global Coupling X->Y Phase I

Global Coupling X->Y Phase II

Global Coupling Y->X Phase I

Global Coupling Y->X Phase II

Integrated LER Emittance Y comparison from MIA calculation Yiton Yan

Dispersion in Interaction Region April 25, 2007

Dispersion Corrections Using Sextupole Bumps

Coupling Correction Using Sextupole Bumps

Completed Tasks (III) April 30, 2007 Improve the new lattice (L=8.0) Dial 15% of full MIA knob with bumps (FJ-D,YY) Use w11,w12,w21,w22 knobs to gain lifetime and luminosity (F-J-D) Lower the x chromaticity by -3.5 unit (FJ-D) Improve the lifetime and background Enlarged the momentum aperture (> 1/3 KHz) Made the positron beam stronger Have to made the electron beam stronger to gain luminosity (FJ-D)

Conclusion Clearly, there are more work to do for this new lattice: both coupling and vertical dispersion. But differences are not that large. We are nearly back to even point at comparable currents relative to Apr 18, 2007. Even we back out the permanent skew quadrupoles, we still have some work to do to reach the Aug. 15, 2006 lattice. This lattice has the potential to surpass the Aug. 15, 2006 lattice. We opened a new region of parameters to gain luminosity with very high specifics. The High Energy Ring needs to be tuned accordingly. We all worked extremely hard on this new lattice, especially FJ-D.

Short-Term Plan Check setting of sextupoles and chromaticity: SF2, SD2 should be weaker: 6.556 and -10.182 (in LEGO init compared to 6.894 and -11.5099) Reduce dispersions and couplings Why large orbit excursion at SK5? Directly correct dispersions Maybe do it at high currents Move nx+ toward the half integer It was not a problem for single beam Build and test IP tuning knobs, including couplings