- Open Access
Energy transparency and symmetries in the beam-beam interaction
Phys. Rev. ST Accel. Beams 3, 024401 – Published 7 February, 2000
DOI: https://doi.org/10.1103/PhysRevSTAB.3.024401
Abstract
We have modified the beam-beam simulation code CBI to handle asymmetric beams and used it to look at energy transparency and symmetries in the beam-beam interaction. We find that even a small violation of energy transparency, or of the symmetry between the two beams, changes the character of the collective (coherent) motion; in particular, period- oscillations are no longer seen. We speculate that the one-time observation of these oscillations at LEP, and the more ubiquitous observation of the flip-flop instability in colliders around the world, may be a consequence of breaking the symmetry between the electron and positron beams. We also apply this code to the asymmetric collider PEP-II, and find that for the nominal parameters of PEP-II, in particular, the nominal tune-shift parameter of , there are no collective beam-beam issues. Collective quadrupole motion sets in only at and above, consistent with earlier observations for symmetric beams.
References (6)
- S. Krishnagopal, Phys. Rev. Lett. 76, 235 (1996); S. Krishnagopal and R. Siemann, 67, 2461 (1991).
- S. Krishnagopal, Centre for Advanced Technology Report No. CAT-95/5, 1995.
- S. Krishnagopal and R. Siemann, Phys. Rev. D 41, 1741 (1990).
- M. Furman and J. Eden, PEP-II AP Note No. 6-92, 1992; ESG Technical Note No. 216, 1993.
- CERN Courier 34, 20 (1994).
- J. L. Tennyson, in Beam Dynamics Issues of High-Luminosity Asymmetric Collider Rings, A. M. Sessler, AIP Conf. Proc. No. 214 (AIP, New York,1990), p. 130.
