On multiple Siberian snakes

Technical Report · Thu Sep 01 00:00:00 EDT 1988

DOI:https://doi.org/10.2172/6813701· OSTI ID:6813701

Yokoya, Kaoru ^[1]

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1. Lawrence Berkeley Lab., CA (USA). SSC Central Design Group National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

The acceleration of polarized proton beams has been done in a number of synchrotrons such as at ANL, Saclay, BNL, and KEK. The theory and technique have been well established up to the energy of few tens of GeV; however, the same technique cannot be applied to an energy range of TeV as in the SSC. For such a machine we need Siberian snakes. As for this clever scheme, however, nothing is known experimentally and even theoretical knowledge is not enough to make reliable predictions for the SSC. It is generally thought that the single and double Siberian snake schemes are insufficient and that we need many pairs of double snakes. The point of controversy now is how many pairs are necessary and sufficient. A most drastic depolarization during acceleration can occur when the spin-orbit resonance condition {nu} = m{sub 0} + m{sub 1}{nu}{sub x} + m{sub 2} {nu}{sub y} + m{sub 3} {nu}{sub s} is satisfied. Here, {nu} is the spin precession tune, {nu}{sub x}, {nu}{sub y}, {nu}{sub s} are the horizontal betatron, vertical betatron and synchrotron tunes and m's are integers. In planar rings, since the spin tune is given by {nu} = {gamma}{alpha} = E/0.52335 GeV to a good approximation, where {gamma} is the beam energy in units of the rest mass and a is the coefficient of the anomalous magnetic moment, the spin tune varies over a large range during acceleration, which makes resonances inevitable. The Siberian snake is an idea to keep the spin tune at some value, usually 1/2, away from any resonance. However, in very high energy rings, perturbations such as machine imperfections and betatron oscillations may change the spin tune considerably so as to cause a resonance. Also, even if the spin tune does not satisfy the first equation, we may have non-resonant depolarization during acceleration. In this paper we shall discuss this problem.

• Research Organization: Lawrence Berkeley Lab., CA (USA). SSC Central Design Group
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC02-89ER40486
• OSTI ID: 6813701
• Report Number(s): SSC-189; ON: DE90013782; TRN: 90-023079
• Country of Publication: United States
• Language: English

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