PAC2013 - List of Authors (Ahrens, L.)

Paper	Title	Page
MOPBA04	Polarization Profile and Spin Dynamics Simulations in the AGS Using the Zgoubi Code	180
	Y. Dutheil, L. Ahrens, H. Huang, F. Méot, V. Schoefer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Polarization transmission during the AGS acceleration cycle is critical for the RHIC polarized proton program, driving strong interest on the exploration of the polarization losses in the AGS. Intrinsic spin resonances are the main source of depolarization in the AGS. This results in the formation of a polarization profile since the strength of such depolarizing resonance depends on the Courant Snyder invariant of each particle. The Zgoubi code and the AGS Zgoubi on-line model now allow to explore the formation of the polarization profile during the acceleration cycle using multi-particle trackings with realistic beam and machine conditions. This paper introduces the specificities of these simulations and compares some of the latest simulated and experimental results.

TUPAC10	Energy Calibration in the AGS Using Depolarization Through Vertical Intrinsic Spin Resonances	466
	Y. Dutheil, L. Ahrens, H. Huang, F. Méot, V. Schoefer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The AGS tune jump system accelerates the crossing of 82 horizontal intrinsic resonances using two fast pulsed quadrupoles. Timing of the tune jumps requires accurate tune and energy measurements. Although cross calibration using measurements of the beam revolution frequency shows good accuracy for most of the AGS energy range it is not adequately sensitive as the beam becomes highly relativistic. This drives a strong interest for a new independent energy measurement method. Reduction in the vertical tune across vertical intrinsic spin resonances can induce important depolarization of the beam. Therefore it was proposed to use the negative vertical tune shift created by this tune jump system to calibrate the energy measurement at few locations along the AGS acceleration cycle. The fast tune jump, of ΔQ≈-0.02 within 100μs in the vertical plane, allows to accurately locate the spin resonant condition, independently from orbit or field conditions. Simulations using the AGS Zgoubi on-line model facilitates the interpretation of the experimental results. This paper introduces the experimental procedure and shows some of the latest results.

THPHO10	Upgrading the RHIC Beam Dump for Higher Intensity	1322
	C. Montag, L. Ahrens, W. Fischer, H. Hahn, C.J. Liaw, J.-L. Mi, S.K. Nayak, T. Roser, P. Thieberger, J.E. Tuozzolo, K. Yip, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Mechanical analysis of the RHIC beam dump window has shown that present heavy ion beam intensities are close to the tolerable limit, and will likely exceed that limit in future runs. Different approaches to upgrade the abort system for those projected higher intensities have been studied, namely replacing the existing window, and adding a vertical kicker that distributes the individual bunches more evenly across the window, thus reducing the heat load. We present the results of these studies and the present status of the upgrade project.

Paper

Title

Page

Polarization Profile and Spin Dynamics Simulations in the AGS Using the Zgoubi Code

180

Y. Dutheil, L. Ahrens, H. Huang, F. Méot, V. Schoefer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Polarization transmission during the AGS acceleration cycle is critical for the RHIC polarized proton program, driving strong interest on the exploration of the polarization losses in the AGS. Intrinsic spin resonances are the main source of depolarization in the AGS. This results in the formation of a polarization profile since the strength of such depolarizing resonance depends on the Courant Snyder invariant of each particle. The Zgoubi code and the AGS Zgoubi on-line model now allow to explore the formation of the polarization profile during the acceleration cycle using multi-particle trackings with realistic beam and machine conditions. This paper introduces the specificities of these simulations and compares some of the latest simulated and experimental results.

TUPAC10

Energy Calibration in the AGS Using Depolarization Through Vertical Intrinsic Spin Resonances

466

Y. Dutheil, L. Ahrens, H. Huang, F. Méot, V. Schoefer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The AGS tune jump system accelerates the crossing of 82 horizontal intrinsic resonances using two fast pulsed quadrupoles. Timing of the tune jumps requires accurate tune and energy measurements. Although cross calibration using measurements of the beam revolution frequency shows good accuracy for most of the AGS energy range it is not adequately sensitive as the beam becomes highly relativistic. This drives a strong interest for a new independent energy measurement method. Reduction in the vertical tune across vertical intrinsic spin resonances can induce important depolarization of the beam. Therefore it was proposed to use the negative vertical tune shift created by this tune jump system to calibrate the energy measurement at few locations along the AGS acceleration cycle. The fast tune jump, of ΔQ≈-0.02 within 100μs in the vertical plane, allows to accurately locate the spin resonant condition, independently from orbit or field conditions. Simulations using the AGS Zgoubi on-line model facilitates the interpretation of the experimental results. This paper introduces the experimental procedure and shows some of the latest results.

THPHO10

Upgrading the RHIC Beam Dump for Higher Intensity

1322

C. Montag, L. Ahrens, W. Fischer, H. Hahn, C.J. Liaw, J.-L. Mi, S.K. Nayak, T. Roser, P. Thieberger, J.E. Tuozzolo, K. Yip, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Mechanical analysis of the RHIC beam dump window has shown that present heavy ion beam intensities are close to the tolerable limit, and will likely exceed that limit in future runs. Different approaches to upgrade the abort system for those projected higher intensities have been studied, namely replacing the existing window, and adding a vertical kicker that distributes the individual bunches more evenly across the window, thus reducing the heat load. We present the results of these studies and the present status of the upgrade project.