Abstract
We recently analyzed all available data on spin-flipping stored beams of polarized protons, electrons, and deuterons. Fitting the modified Froissart-Stora equation to the measured polarization data after crossing an rf-induced spin resonance, we found 10--20-fold deviations from the depolarizing resonance strength equations used for many years. The polarization was typically manipulated by linearly sweeping the frequency of an rf dipole or rf solenoid through an rf-induced spin resonance; spin-flip efficiencies of up to $99.9%$ were obtained. The Lorentz invariance of an rf dipole's transverse $\ensuremath{\int}Bdl$ and the weak energy dependence of its spin resonance strength $\mathcal{E}$ together imply that even a small rf dipole should allow efficient spin flipping in 100 GeV or even TeV storage rings; thus, it is important to understand these large deviations. Therefore, we recently studied the resonance strength deviations experimentally by varying the size and vertical betatron tune of a $2.1\text{ }\text{ }\mathrm{GeV}/c$ polarized proton beam stored in COSY. We found no dependence of $\mathcal{E}$ on beam size, but we did find almost 100-fold enhancements when the rf spin resonance was near an intrinsic spin resonance.
Highlights
Polarized beam experiments have become an important part of the programs in storage rings such as the IUCF Cooler Ring [1], AmPS at NIKHEF [2], the MIT-Bates Storage Ring [3], COSY [4], LEP at CERN [5], RHIC at BNL [6] and HERA at DESY [7,8]
We did this by varying the size and the vertical betatron tune of a 2:1 GeV=c polarized proton beam stored in COSY
By compiling existing data and fitting it to the Froissart-Stora equation, we first found 10 –20-fold deviations from the spin resonance strength equation that has been used for many years
Summary
Polarized beam experiments have become an important part of the programs in storage rings such as the IUCF Cooler Ring [1], AmPS at NIKHEF [2], the MIT-Bates Storage Ring [3], COSY [4], LEP at CERN [5], RHIC at BNL [6] and HERA at DESY [7,8]. The vertical polarization can be perturbed by an rf magnet’s horizontal rf magnetic field This perturbation can induce an rf depolarizing resonance, which can flip the spin direction of stored polarized particles [12 –25]; the resonance’s frequency is fr fc k s;. One can obtain the resonance strength EBdl due to an rf solenoid or rf dipole using solenoid : EBdl. Rwhere e is the particle’s charge, p is its momentum, and Brmsdl is the rf magnet’s rms magnetic field integral in its rest frame [26 –28]. Rwhere e is the particle’s charge, p is its momentum, and Brmsdl is the rf magnet’s rms magnetic field integral in its rest frame [26 –28] These equations are for an ideal flat circular accelerator with a point rf magnet causing the only perturbation of the spin motion.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical Review Special Topics - Accelerators and Beams
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
