BNL, Upton, Long Island, New York, USA
Jacobs Engineering, Pasadena, USA
University of Huddersfield, Huddersfield, United Kingdom
IPN, Orsay, France
Fermilab, Batavia, USA
JLAB, Newport News, Virginia, USA
Thor Energy, Oslo, Norway
ESS, Lund, Sweden
Texas A&M University, College Station, Texas, USA
IThEO, Sweden
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
University of Cambridge, Cambridge, United Kingdom
BNL, Upton, Long Island, New York, USA
As the world’s first high energy polarized proton collider, RHIC has made significant progress in measuring the proton spin structure in the past decade. In order to have better understanding of the contribution of up and down quarks to the proton spin structure, collisions of high energy polarized neutron beams are required. In this paper, we present studies of accelerating polarized Helium-3 in RHIC with the current dual snake configuration. The possibilities of adding two more pairs of snakes for accelerating polarized He-3 were explored. Results of a six snake configuration in RHIC are also reported in the paper.
BNL, Upton, Long Island, New York, USA
In this article we calculate and compare the off-momentum dynamic aperture for lattices with different phase advances per FODO cell in the RHIC heavy ion runs. A lattice with an increased phase advance was adopted in 2008-2011 to reduce transverse emittance growth rates from intra-beam scattering. However, during these runs, a large beam loss was observed with longitudinal RF re-bucketing which increased the momentum spread. With operational transverse stochastic cooling in the 2011 RHIC heavy ion run, the transverse intra-beam scattering emittance growth was eliminated, and the beam loss during stores was determined by the off-momentum aperture and burn-off from luminosity. We investigate the possibilities to increase the off-momentum dynamic aperture that would lead to an increase in the integrated luminosity.
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
Tech-X, Boulder, Colorado, USA
JLAB, Newport News, Virginia, USA
BINP SB RAS, Novosibirsk, Russia
Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o’clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.
BNL, Upton, Long Island, New York, USA
The five ac dipole design of RHIC spin flipper in the Blue ring was first commissioned during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper*. Spin flipping efficiency was measured with both 100 GeV and 250 GeV polarized proton beams. This paper presents the latest commissioning results.
* M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010
BNL, Upton, Long Island, New York, USA
In addition to collisions of electrons with various unpolarized ion species as well as polarized protons, the proposed electron-hadron collider (eRHIC) will also facilitate the collisions of electrons with polarized 3He ions. The AGS is the last acceleration stage of ions before injection into one RHIC for final acceleration. The AtR (AGS to RHIC) transfer line will be utilized to transport the polarized 3He ions from AGS into one of the RHIC’s collider rings. In this paper we investigate the extraction energy of the polarized 3He ions from the AGS which will optimize the polarization of 3He ions injected into RHIC. Some of the peculiarities (interleaved horizontal and vertical bends) of the AtR line's layout may degrade this spin matching of the polarized 3He ions. We will also discuss possible simple modifications of the AtR line to accomplish a perfect “spin matching” of the injected 3He beam with that of the stable spin direction at the injection point of the RHIC ring.
BNL, Upton, Long Island, New York, USA
The idea* of using two partial helical magnets was applied successfully to the AGS synchrotron**, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides a larger “spin tune gap” for the placement of both the vertical and horizontal tunes of the AGS during acceleration, second. Although the same spin gap can be obtained with two partial helices of equal strength, the required strength of the two helices makes it impractical. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and comparison of these results with the present setup of the AGS that uses two partial helical magnets***.
* T. Roser et al., Proc. EPAC04, p. 1577 (2004).
** H. Huang et al., PRL 99, 154801(2007).
*** N. Tsoupas et. al., these proceedings.
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
The high energy (T=250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, two partial helical magnets* have been installed in AGS. In order to minimize the loss of the beam polarization due to the various intrinsic spin resonances occurring during the proton acceleration, we constrain the value of the vertical tune to be higher than 8.97. With the AGS running at near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads** in AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices.
* H. Huang, et al., Proc. EPAC06, p. 273, (2006).
** N. Tsoupas et al., Proc. PAC07, p. 3723 (2007).
BNL, Upton, Long Island, New York, USA
INFN/LNS, Catania, Italy
CSFNSM, Catania, Italy
BNL, Upton, Long Island, New York, USA
Over the last few years, physicists have suspected the presence of noise acting on the RHIC beams observable as occasional emittance growth at high beam energies. While the noise was sporadic in the past, it became more persistent during the run-11 setup period. An investigation diagnosed the source as originating from the RHIC abort kicker system. Once identified the issue was quickly resolved. We report in this paper the investigation result, circuit analysis, measured and simulated waveforms, solutions, and future plans.