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Title: Studies of polarized beam acceleration and Siberian Snakes

Abstract

We studied depolarization mechanisms of polarized proton acceleration in high energy accelerators with snakes and found that the perturbed spin tune due to the imperfection resonance plays an important role in beam depolarization at snake resonances. We also found that even order snake resonances exist in the overlapping intrinsic and imperfection resonances. Due to the perturbed spin tune of imperfection resonances, each snake resonance splits into two. Thus the available betatron tune space becomes smaller. Some constraints on polarized beam colliders were also examined.

Authors:
Publication Date:
Research Org.:
Indiana Univ., Bloomington, IN (United States). Dept. of Physics
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10172834
Report Number(s):
DOE/ER/40747-3; CONF-921131-13
ON: DE93017207; TRN: 93:017884
DOE Contract Number:
FG02-92ER40747
Resource Type:
Conference
Resource Relation:
Conference: 10. international symposium on high-energy spin physics,Nagoya (Japan),9-14 Nov 1992; Other Information: PBD: [1992]
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; POLARIZED BEAMS; EQUATIONS OF MOTION; SYNCHROTRONS; PROTON BEAMS; BETATRON OSCILLATIONS; SPIN; COLLIDING BEAMS; TUNING; 430200; BEAM DYNAMICS, FIELD CALCULATIONS, AND ION OPTICS

Citation Formats

Lee, S.Y. Studies of polarized beam acceleration and Siberian Snakes. United States: N. p., 1992. Web.
Lee, S.Y. Studies of polarized beam acceleration and Siberian Snakes. United States.
Lee, S.Y. Thu . "Studies of polarized beam acceleration and Siberian Snakes". United States. doi:. https://www.osti.gov/servlets/purl/10172834.
@article{osti_10172834,
title = {Studies of polarized beam acceleration and Siberian Snakes},
author = {Lee, S.Y.},
abstractNote = {We studied depolarization mechanisms of polarized proton acceleration in high energy accelerators with snakes and found that the perturbed spin tune due to the imperfection resonance plays an important role in beam depolarization at snake resonances. We also found that even order snake resonances exist in the overlapping intrinsic and imperfection resonances. Due to the perturbed spin tune of imperfection resonances, each snake resonance splits into two. Thus the available betatron tune space becomes smaller. Some constraints on polarized beam colliders were also examined.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Dec 31 00:00:00 EST 1992},
month = {Thu Dec 31 00:00:00 EST 1992}
}

Conference:
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  • Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20-30% partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction.
  • Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20-30% partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction.
  • We successfully injected polarized protons in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. Each snake consists of four helical superconducting dipoles which rotate the polarization by 180{sup o} about a horizontal axis. This is the first time that polarized protons have been accelerated to 100 GeV. We report on our experiences during commissioning and operation of collider with polarized protons.
  • Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.
  • The RHIC spin program requires 2 x 10{sup 11} proton/bunch with 70% polarization. As the injector to RHIC, AGS is the bottleneck for preserving polarization: there is no space for a full snake to overcome numerous depolarizing resonances. An ac dipole and a partial snake have been used to preserve beam polarization in the past few years. Two helical snakes have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate all depolarizing resonances encountered during acceleration. This paper presents the setup and preliminary results.