dorsal/arxiv
View SchemaOptimal Axes of Siberian Snakes for Polarized Proton Acceleration
| Authors | Georg H. Hoffstaetter |
|---|---|
| Categories | |
| ArXiv ID | physics/0405109 |
| URL | https://arxiv.org/abs/physics/0405109 |
| DOI | 10.1103/PhysRevSTAB.7.121001 |
| Journal | Phys.Rev.STAccel.Beams7:121001,2004 |
Abstract
Accelerating polarized proton beams and storing them for many turns can lead to a loss of polarization when accelerating through energies where a spin rotation frequency is in resonance with orbit oscillation frequencies. First-order resonance effects can be avoided by installing Siberian Snakes in the ring, devices which rotate the spin by 180 degrees around the snake axis while not changing the beam's orbit significantly. For large rings, several Siberian Snakes are required. Here a criterion will be derived that allows to find an optimal choice of the snake axes. Rings with super-period four are analyzed in detail, and the HERA proton ring is used as an example for approximate four-fold symmetry. The proposed arrangement of Siberian Snakes matches their effects so that all spin-orbit coupling integrals vanish at all energies and therefore there is no first-order spin-orbit coupling at all for this choice, which I call snakes matching. It will be shown that in general at least eight Siberian Snakes are needed and that there are exactly four possibilities to arrange their axes. When the betatron phase advance between snakes is chosen suitably, four Siberian Snakes can be sufficient. To show that favorable choice of snakes have been found, polarized protons are tracked for part of HERA-p's acceleration cycle which shows that polarization is preserved best for the here proposed arrangement of Siberian Snakes.
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"abstract": "Accelerating polarized proton beams and storing them for many turns can lead\nto a loss of polarization when accelerating through energies where a spin\nrotation frequency is in resonance with orbit oscillation frequencies.\nFirst-order resonance effects can be avoided by installing Siberian Snakes in\nthe ring, devices which rotate the spin by 180 degrees around the snake axis\nwhile not changing the beam\u0027s orbit significantly. For large rings, several\nSiberian Snakes are required.\n Here a criterion will be derived that allows to find an optimal choice of the\nsnake axes. Rings with super-period four are analyzed in detail, and the HERA\nproton ring is used as an example for approximate four-fold symmetry. The\nproposed arrangement of Siberian Snakes matches their effects so that all\nspin-orbit coupling integrals vanish at all energies and therefore there is no\nfirst-order spin-orbit coupling at all for this choice, which I call snakes\nmatching. It will be shown that in general at least eight Siberian Snakes are\nneeded and that there are exactly four possibilities to arrange their axes.\nWhen the betatron phase advance between snakes is chosen suitably, four\nSiberian Snakes can be sufficient.\n To show that favorable choice of snakes have been found, polarized protons\nare tracked for part of HERA-p\u0027s acceleration cycle which shows that\npolarization is preserved best for the here proposed arrangement of Siberian\nSnakes.",
"arxiv_id": "physics/0405109",
"authors": [
"Georg H. Hoffstaetter"
],
"categories": [
"physics.acc-ph"
],
"doi": "10.1103/PhysRevSTAB.7.121001",
"journal_ref": "Phys.Rev.STAccel.Beams7:121001,2004",
"title": "Optimal Axes of Siberian Snakes for Polarized Proton Acceleration",
"url": "https://arxiv.org/abs/physics/0405109"
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