Effect of Overlapping Intrinsic Spin Resonances on e-Lens Lattices from FY13 Polarized Proton Run

Vahid H Ranjbar

doi:10.1142/s2010194516600880

Abstract

During the 2013 Polarized Proton run RHIC was run with a lattice designed to accommodate the phases necessary for the Electron lens. This lattice resulted in significant changes in magnitude and distribution of the intrinsic resonances. The overall magnitude of the strong intrinsic resonances were smaller, however the neighbouring weak intrinsic resonances grew. We present results from 2D direct tracking with 5,000 particles and 2D lattice independent tracking .

Highlights

One of the major limitations for high intensity colliders are due to the head on beam-beam collisions which with a high enough intensity can lead to emittance blow-up
In order to compensate this effect an electron lens[1] has been installed in the Relativistic Heavy Ion Collider (RHIC). In order for this compensation to work effectively the betatron phase advance between the collisional interaction point (IP) and the e-lens should be fixed at 90 degrees
Re-use and distribution is strictly not permitted, except for Open Access articles. This was the first time the RHIC lattice had run with significantly altered intrinsic spin resonance structure

Summary

Indroduction

One of the major limitations for high intensity colliders are due to the head on beam-beam collisions which with a high enough intensity can lead to emittance blow-up. Effect of Overlapping Spin Resonances on e-Lens Lattices signatures for polarization loss.[6] So after considering the single resonance model under resonances strengths (0 - 5) over a whole range of irrational tunes (0-1.0) our conjecture is that provided we begin tracking on the stable spin direction and compare final spin orientation with the final stable spin direction that there is no mechanism to move the spin vector away from the stable spin direction for acceleration rates common in RHIC This conjecture is based on our tracking with the single resonance model with orthogonal snakes and the understanding that for this system the spin tune is amplitude independent. What are the thresholds in strength and distance from the main resonance? What role does phase play?

Bench Marking Lattice Independent Tracking

Effect of Overlapping Resonances