Abstract
This paper proposes a new design of spin flipper for high-energy accelerators to obtain full spin flip with the spin tune staying at half integer. The traditional technique of using a single rf spin rotator with a fixed spin rotation axis and an oscillating spin rotation, either an rf dipole or solenoid, as spin flipper to achieve full spin flip in the presence of a full Siberian snake has been demonstrated [B. B. Blinov et al., Phys. Rev. Lett. 81, 2906 (1998); B. B. Blinov et al., Phys. Rev. Lett. 88, 014801 (2001); V. S. Morozov et al., Phys. Rev. ST Accel. Beams 7, 024002 (2004); R. A. Phelps, AIP Conf. Proc. 338, 361 (1994); Ya. S. Derbenev et al., Part. Accel. 8, 115 (1978)]. However, this technique requires one to change the snake configuration to move the spin tune away from half integer which is not practical for an operational high-energy polarized proton collider such as RHIC where beam and polarization lifetime are sensitive to small changes. Based on the conceptual designs to use rf dipoles to achieve full spin flip with the spin tune at half integer [T. Roser, BNL Report No. BNL-52453, 1994; R. A. Phelps, BNL Report No. BNL-52453, 1994], this paper presents a compact design of a spin flipper for a high-energy accelerator. The theory of the new spin flipper technique and numerical simulations are also presented.
Highlights
In order to cancel the systematic errors in experiments of high-energy polarized proton collisions, one would like to reverse the spin directions of the two colliding beams multiple times during the store when data are taken
For the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, two pairs of full Siberian snakes were installed in the two rings
With the two snakes in each ring, the spinor one turn map of RHIC in the presence of the spin flipper is given by OTM 1⁄4 ðÀi2ÞeÀði=2ÞG 3 ðÀi1ÞeÀði=2ÞG 3 eði=2Þð=4Þ3
Summary
This paper proposes a new design of spin flipper for high-energy accelerators to obtain full spin flip with the spin tune staying at half integer. This technique requires one to change the snake configuration to move the spin tune away from half integer which is not practical for an operational high-energy polarized proton collider such as RHIC where beam and polarization lifetime are sensitive to small changes. Based on the conceptual designs to use rf dipoles to achieve full spin flip with the spin tune at half integer [T. The theory of the new spin flipper technique and numerical simulations are presented
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