Hourglass effects for asymmetric colliders
Conference
·
OSTI ID:5740920
We give the expressions for the geometrical reduction factor of the luminosity and the geometrical beam-beam aggravating factor'' for the general asymmetric case, for tri-gaussian bunches colliding head on. With these formulas we attempt a (limited) analytic understanding of the multiparticle tracking simulations carried out for the proposed SLAC/LBL/LLNL B factory when parasitic crossings are ignored. We conclude the following: (a) the geometrical reduction in luminosity is {approximately}6% relative to the zero-bunch-length (nominal) value; (b) only the vertical beam-beam parameter of the LER is significantly altered by the hourglass effect: the geometrical enhancement of the central positron's vertical beam-beam parameter is {approximately}10% relative to the nominal value, and (c) the positrons at the head or tail of the bunch have vertical beam-beam parameters much larger than nominal. We discuss the electromagnetic disruption effect only qualitatively. This effect probably compensates (or overcompensates) the geometrical reduction of the luminosity, and it is possibly detrimental for the beam-beam parameters. 7 refs., 3 figs.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5740920
- Report Number(s):
- LBL-30833; CONF-910505--333; ON: DE91014449
- Country of Publication:
- United States
- Language:
- English
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