BNL, Upton, Long Island, New York, USA
A critical point for the polarized proton program of the RHIC is the polarization transmission through the AGS acceleration cycle. Recent developments in the Zgoubi model of the AGS allow multi-particle tracking with realistic beam and machine conditions on a large scale computing system. This gives the opportunity to simulate the influence of many beam and machine conditions on the polarization transmission and leads to a better understanding of the depolarization processes, for instance the horizontal intrinsic resonances, that cannot be accurately explored by the conventional simulation approaches or by the experiments with beam. This paper introduces the developments realized on the Zgoubi code to run these simulations and shows some of the latest results.
Tech-X, Boulder, Colorado, USA
BNL, Upton, Long Island, New York, USA
DESY, Hamburg, Germany
Graphics processing units (GPUs) have now become powerful tools for scientific computation. Here we present our work on using GPUs (singly or in parallel) to speed the tracking of both orbital and spin degrees of freedom in particle accelerators. This work includes the development of new spin integrators that are both fast and accurate. We have also developed an integrated set of tools for analysing the results. To demonstrate the utility of these new tools, we use them to study the spin dynamics of protons in the Relativistic Heavy Ion Collider at Brookhaven National Lab.
BNL, Upton, Long Island, New York, USA
As the world’s only high energy polarized proton collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been providing collisions of polarized proton beams at beam energy from 100~GeV to 255~GeV for the past decade to explore the proton spin structure as well as other spin dependent measurements. With the help of two Siberian Snakes per accelerator plus outstanding beam control, beam polarization is preserved up to 100~GeV. About 10% polarization loss has been observed during the acceleration between 100~GeV and 255~GeV due to several strong depolarizing resonances. Moderate polarization loss was also observed during a typical 8 hour physics store. This presentation will overview the achieved performance of RHIC, both polarization as well as luminosity. The plan for providing high energy polarized He-3 collisions at RHIC will also be covered.
This work is on behalf of RHIC team.
BNL, Upton, Long Island, New York, USA
To search for the critical point in the QCD phase diagram, RHIC needs to operate at a set of low gold beam energies between 2.5 and 20 GeV per nucleon. During run 12, first successful collider operation at the lowest energy of 2.5 GeV per nucleon was achieved. We present the challenges and achieved results, and discuss possible future upgrades and improvements.
BNL, Upton, Long Island, New York, USA
We performed numerical simulations to study the effects of head-on beam-beam compensation with the realistic RHIC lattices. To better cancel the beam-beam resonance driving terms during half beam-beam compensation operation, the betatron phase advances between the interaction point IP8 and the center of the electron lens should be multiples of pi. for this purpose two shunt power supplies were added to the main quadrupole circuit buses in the arc between them. For the realistic beam-beam compensation lattices, the integer tunes are (27, 29) for the Blue ring and (29, 30) for the Yellow ring. The betatron phase advances between IP8 and the e-lens are (8pi,11pi) in the Blue ring and (11pi, 9pi) in the Yellow ring. Recent simulation results will be presented.
BNL, Upton, Long Island, New York, USA
UCR, Riverside, California, USA
The 2013 operation of the Relativistic Heavy Ion Collider (RHIC) marks the second year of running under the RHIC II era. Additionally this year saw the implementation of several important upgrades designed to push the intensity frontier. Two new E-lenses have been installed, along with a new lattice designed for the E-lens operation. A new polarized proton source which generates about factor of 2 more intensity was commissioned as well as a host of RF upgrades from a new longitudinal damper, Landau cavity in RHIC to a new low level RF and new harmonic structure for the AGS. We present an overview of the challenges and results from this years run.
BNL, Upton, Long Island, New York, USA
At the Relativistic Heavy Ion Collider (RHIC) at BNL the physics program includes collisions between beams of polarized protons at high beam energies. Maintaining the proton's polarization is vital and preserved primarily by application of a pair of Siberian snakes. Measurements from recent high-energy physics runs indicate polarization loss during acceleration between 100 and 250 GeV. Based on analytic estimations for off-momentum particles and/or beams, a nonzero difference in DX prime - the dispersion function angle - between the snakes can result in a shift in the spin tune, or equivalently, of the conditions of snake resonances in close proximity to the beam during acceleration. Requiring that DX prime at the two Siberian snakes in RHIC being equal would reduce the spin tune shift for off-energy particles so helping to maintain polarization during the energy ramp. Preservation of half-integer spin tune is also important for future operation of the spin flipper at store. In this report, the matching scheme and simulations using MAD-X will be presented together with a newly applied method based on response matrices.
BNL, Upton, Long Island, New York, USA
This paper gives a status of the AGS model in the ray-tracing code Zgoubi and its operation via the ‘‘AgsZgoubiModel'' and the ‘‘AgsModelViewer'' applications available from the controls system application launcher, ‘‘StartUp''. Examples of typical uses and studies performed using these are included, as optics controls, spin matching to RHIC, etc. A companion paper (MOPWA085) gives additional details, regarding especially spin dynamics and polarization studies aimed at determining optimal AGS settings for polarization during RHIC Run 13. This work is an additional step towards further combination with the already existing RHIC spin tracking model in Zgoubi, and AGS's Booster model in Zgoubi, a promising suite for detailed beam and spin dynamics studies and optimizations.