Compensation of the {open_quotes}Pacman{close_quotes} tune spread by tailoring the beam current

Conference · Sat Apr 01 04:00:00 EST 1995

OSTI ID:97353

Furman, M A

{open_quotes}Factory{close_quotes}-like e{sup +}-e{sup {minus}} colliders presently under design or construction achieve high luminosity by resorting to large numbers of closely-spaced bunches. The short bunch spacing implies that there are unavoidable parasitic collisions (PCs) in the neighborhood of the interaction point (IP). Since the bunch population of the beam is not uniform due to an intentional ion-clearing gap, the bunches at the head or tail of the train ({open_quotes}pacman bunches{close_quotes}) experience different beam-beam tune shifts than those away from the edges ({open_quotes}typical bunches{close_quotes}). The author presents here a method to minimize the vertical tune spread at the expense of increasing the horizontal tune spread (it is assumed that there is only one IP). Since the beam-beam dynamics for flat beams typically tolerates a significantly higher horizontal tune spread than a vertical tune spread, this method implies a net advantage. The author presents this discussion in the context of the PEP-II collider.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 97353
• Report Number(s): LBL--36471; CONF-950512--295; ON: DE95016415
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BEAM BUNCHING
BEAM DYNAMICS
COLLIDING BEAMS
ELECTRON-POSITRON INTERACTIONS
TUNING