Abstract
The figure-8-shaped ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC) is transparent to the spin. It allows one to preserve proton and deuteron polarizations using weak stabilizing solenoids when accelerating the beam up to 100 GeV/c. When the stabilizing solenoids are introduced into the collider’s lattice, the particle spins precess about a spin field, which consists of the field induced by the stabilizing solenoids and the zero-integer spin resonance strength. During acceleration of the beam, the induced spin field is maintained constant while the resonance strength experiences significant changes in the regions of “interference peaks”. The beam polarization depends on the field ramp rate of the arc magnets. Its component along the spin field is preserved if acceleration is adiabatic. We present the results of our theoretical analysis and numerical modeling of the spin dynamics during acceleration of protons and deuterons in the JLEIC ion collider ring. We demonstrate high stability of the deuteron polarization in figure-8 accelerators. We analyze a change in the beam polarization when crossing the transition energy.
Highlights
To preserve the polarizations of the proton and deuteron beams during acceleration from 8 GeV/c to 100 GeV/c in the ion collider ring, it is sufficient to use a weak solenoid with a field integral of 1.2 T m, which does not perturb the design orbit and has practically no effect on the beam’s orbital parameters [3,4,5,6,7,8,9,10]
The graphs of the longitudinal spin components practically do not differ from each other, i.e. synchrotron energy modulation does not give a noticeable contribution to the ion spin motion when stabilizing the polarization by a weak solenoid in the Jefferson Lab Electron-Ion Collider (JLEIC) ion collider ring
Crossing the transition energy When accelerating polarized protons and deuterons in the JLEIC ion collider ring in the momentum range from 8 GeV/c to 100 GeV/c, one has to consider the question of preserving the beam polarization during transition energy crossing
Summary
To preserve the polarizations of the proton and deuteron beams during acceleration from 8 GeV/c to 100 GeV/c in the ion collider ring, it is sufficient to use a weak solenoid with a field integral of 1.2 T m, which does not perturb the design orbit and has practically no effect on the beam’s orbital parameters [3,4,5,6,7,8,9,10]. The resonance strength is the average spin field ω⃗ (the zero-integer Fourier harmonic of the spin perturbation without a stabilizing solenoid) determined by deviation of the trajectory from the design orbit due to machine element errors and beam emittances.
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