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ABSTRACT: The commissioning of the RHIC spin flipper in the RHIC Blue ring during the RHIC polarized proton run in 2009 showed the detrimental effects of global vertical coherent betatron oscillation induced by the 2-AC dipole plus 4-DC dipole configuration [1]. This global orbital coherent oscillation of the RHIC beam in the Blue ring in the presence of collision modulated the beam-beam interaction between the two RHIC beams and affected Yellow beam lifetime. The experimental data at injection with different spin tunes by changing the snake current also demonstrated that it was not possible to induce a single isolated spin resonance with the global vertical coherent betatron oscillation excited by the two AC dipoles. Hence, RHIC spin flipper was re-designed to eliminate the coherent vertical betatron oscillation outside the spin flipper by adding three additional AC dipoles. This paper presents the experimental results as well as the new design.
Journal of Physics Conference Series 05/2011; 295(1):012162.
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M Minty,
A Curcio,
C Dawson,
C Degen,
Y Luo,
G Marr,
B Martin,
A Marusic,
K Mernick, P Oddo,
Others
BNL C-AD AP Note. 01/2010; 366(August).
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M. Bai,
L. Ahrens,
I.G. Alekseev,
J. Alessi,
J. Beebe-Wang,
M. Blaskiewicz,
A. Bravar,
J.M. Brennan,
K. Brown,
D. Bruno, [......],
D.N. Svirida,
D. Trbojevic,
N. Tsoupas,
J. Tuozzolo,
M. Wilinski,
S. Tepikian,
A. Zaltsman,
A. Zelenski,
K. Zeno,
S.Y. Zhang
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ABSTRACT: The relativistic heavy ion collider (RHIC) as the first high energy polarized proton collider was designed to provide polarized proton collisions at a maximum beam energy of 250 GeV. It has been providing collisions at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated to the record energy of 250 GeV in RHIC with a polarization of 46% measured at top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival to orbit distortions.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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ABSTRACT: As part of the Low Level RF (LLRF) upgrade project at Brookhaven National Laboratory's Collider-Accelerator Department (BNL C-AD), we have recently developed and tested a prototype high performance embedded controller. This controller is a custom designed PMC module employing a Xilinx V4FX60 FPGA with a PowerPC405 embedded processor, and a wide variety of on board peripherals (DDR2 SDRAM, FLASH, Ethernet, PCI, multi-gigabit serial transceivers, etc.). The controller is capable of running either an embedded version of LINUX or VxWorks, the standard operating system for RHIC front end computers (FECs). We have successfully demonstrated functionality of this controller as a standard RHIC FEC and tested all on board peripherals. We now have the ability to develop complex, custom digital controllers within the framework of the standard RHIC control system infrastructure. This paper will describe various aspects of this development effort, including the basic hardware, functional capabilities, the development environment, kernel and system integration, and plans for further development.
