Beam-beam tune shifts and spreads in the SSC (Superconducting Super Collider): Head on, long range, and PACMAN conditions
- Texas Accelerator Center, The Woodlands, TX (USA)
- Lawrence Berkeley Lab., CA (USA). SSC Central Design Group
This note analyses the regions of the tune plane which are occupied in a (nominal) model SSC which has two collision points with {beta}* = 0.5 metres, and two with {beta}* = 10.0 metres. The full crossing angle at each collision point is taken to be {alpha}* = 75 microradians, and the head on tune shift parameter is {xi} = {minus}0.00084, (significantly less than the SPS parameter {xi}{sub SPS} {approx} 0.004). Long range beam-beam interactions take place in the free spaces on either side of the collision point, {plus minus}L = 72 metres for the low beta IRs, and 150 metres in the high beta IRs, which are assumed for convenience to be pure drifts. Bunches in one beam are longitudinally separated from each other by S{sub B} = 4.8 metres. In one variant of the model the transverse beam separation is vertical in all cases, while in a second variant alternate crossings are vertical and horizontal. In both of these cases the horizontal and vertical tune shifts of a test particle in a nominal bunch, and in a PACMAN bunch, are calculated and plotted as a function of its transverse amplitudes, (a{sub x}, a{sub Y}), which are conveniently measured in units of {sigma}, the rms size of the incident gaussian beam. Similar results to these have also been reported elsewhere.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA). SSC Central Design Group
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC02-89ER40486
- OSTI ID:
- 6722673
- Report Number(s):
- SSC-63; ON: DE90014690; TRN: 90-028695
- Country of Publication:
- United States
- Language:
- English
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