Author: Borland, M.
Paper Title Page
THPC074 Dynamic Aperture and Tolerances for PEP-X Ultimate Storage Ring Design 3065
 
  • M.-H. Wang, Y. Cai, R.O. Hettel, Y. Nosochkov
    SLAC, Menlo Park, California, USA
  • M. Borland
    ANL, Argonne, USA
 
  Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
A lat­tice for the PEP-X ul­ti­mate stor­age ring light source[1], hav­ing 11 pm-rad nat­u­ral emit­tance at a beam en­er­gy of 4.5 GeV at zero cur­rent, using 90 m of damp­ing wig­gler and fit­ting into the ex­ist­ing 2.2-km PEP-II tun­nel, has been re­cent­ly de­signed[2]. Such a low emit­tance lat­tice re­quires very strong sex­tupoles for chro­matic­i­ty cor­rec­tion, which in turn in­tro­duce strong non-lin­ear field ef­fects that limit the beam dy­nam­ic aper­ture. In order to max­i­mize the dy­nam­ic aper­ture we choose the cell phas­es to can­cel the third and fourth order ge­o­met­ric res­o­nances in each 8-cell arc. Four fam­i­lies of chro­mat­ic sex­tupoles and six fam­i­lies of ge­o­met­ric (or har­mon­ic) sex­tupoles are added to cor­rect the chro­mat­ic and am­pli­tude-de­pen­dent tunes. To find the best set­tings of the ten sex­tupole fam­i­lies, we use a Mul­ti-Ob­jec­tive Ge­net­ic Op­ti­miz­er em­ploy­ing el­e­gant[3] to op­ti­mize the beam life­time and dy­nam­ic aper­ture si­mul­ta­ne­ous­ly. Then we eval­u­ate dy­nam­ic aper­ture re­duc­tion caused by mag­net­ic field mul­ti­pole er­rors, mag­net fab­ri­ca­tion er­rors and mis­align­ments. A suf­fi­cient dy­nam­ic aper­ture is ob­tained for in­jec­tion, as well as work­able beam life­time[2].