BNL, Upton, Long Island, New York, USA
RHIC operation as the polarized proton collider presents unique challenges since both luminosity and spin polarization are important. With longitudinally polarized beams at the experiments, the figure of merit is LP4. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system has been installed to improve longitudinal match at injection and to increase luminosity. The beam dumps were upgraded to allow for increased bunch intensities. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control has also been improved this year. Additional efforts were put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point was chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper.
BNL, Upton, Long Island, New York, USA
We present a lattice design of a CW Electron Recovery Linacs (ERL) for future electron-hadron colliders eRHIC and LHeC. In eRHIC, an six-pass ERL installed in the existing Relativistic Heavy Ion Collider (RHIC) tunnel will collide 5-30 GeV polarized electrons with RHIC’s 50-250 (325) GeV polarized protons or 20-100 (130) GeV/u heavy ions. In LHeC, a stand-along 3-pass 60 GeV CW ERL will collide polarized electrons with 7 TeV protons. After collision, electron beam energy is recovered and electrons are dumped at low energy. Two superconducting linacs are located in the two straight sections in both ERLs. . The multiple arcs are made of Flexible Momentum Compaction lattice (FMC) allowing adjustable momentum compaction for electrons with different energies. The multiple arcs, placed above each other, are matched to the two linacs straight sections with splitters and combiners.
BNL, Upton, Long Island, New York, USA
A model of the Alternating Gradient Synchrotron is being developed based on stepwise ray-tracing numerical tools. It provides a realistic representation of the lattice, and accounts for the two helical partial Siberian snake insertions. The aim is to make this stepwise ray-tracing based model an aid for the understanding of the AGS, in matter of both beam dynamics and polarization transmission.
BNL, Upton, Long Island, New York, USA
* V.N. Litvinenko, I. Ben-Zvi, Proceedings of FEL'2004, http://jacow.org/f04/papers/WEBOS04/
BNL, Upton, Long Island, New York, USA
We are presenting the layout and the optics of a beam line to be used as a medical gantry in radiation therapy. The optical properties of the gantry’s beam line are such as to make the beam line achromatic and uncoupled. These two properties make the beam spot size, which is delivered and focused by the gantry, on the tumor of the patient, independent of the angular orientation of the gantry. In this paper we present the layout of the magnetic elements of the gantry, and also present the theoretical basis for the optics design of such a gantry.
* N. Tsoupas et. al. “Uncoupled achromatic tilted S-bend” Presented at the 11th Biennial European Particle Accelerator Conference, Genoa, Italy, June 23-27,2008
BNL, Upton, Long Island, New York, USA
FRIB, East Lansing, Michigan, USA
MIT, Middleton, Massachusetts, USA
We present the design of future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 1034 cm-2 s-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling and the compact magnets for recirculating passes. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs and a potential of adding polarized positrons are also presented.
BNL, Upton, Long Island, New York, USA
As part of the search for a phase transition or critical point on the QCD phase diagram, an energy scan including 5 different energy settings was performed during the 2010 RHIC heavy ion run. While the top beam energy for heavy ions is at 100 GeV/n and the lowest achieved energy setpoint was significantly below RHICs injection energy of approximately 10 GeV/n, we also provided beams for data taking in a medium energy range above injection energy and below top beam energy. This paper reviews RHIC experience and challenges for RHIC medium energy operations that produced full experimental data sets at beam energies of 31.2 GeV/n and 19.5 GeV/n.
BNL, Upton, Long Island, New York, USA
The RHIC polarized proton physics program requires high luminosity and high polarization which depends directly on the intensity, emittances and polarization delivered to RHIC by the injector chain. In the AGS, two partial snakes create gaps in the realized spin-tune around the integers which allows an accelerating beam with sufficiently small vertical emittance and near-integer vertical tune to avoid the imperfection and vertical intrinsic resonances. The same strategy strengthens the many (82) weak horizontal intrinsic resonances crossed during AGS acceleration. A system speeding up these resonance crossings – the AGS JumpQuad system: 82 tiny (0.04) fast (100usec) betatron tune shifts – has been commissioned and evolved during RHIC Runs 09, 10, and 11. Subtle properties of the AGS geometry and lattice, magnified into relevance by the high vertical tune can result in polarization-damaging emittance growth when combined with the Jump Quad gymnastics. Orbit stability is critical. Some aspects of the JumpQuad system, of this commissioning effort and related developments will be described.