Commissioning and future plans for polarized protons in RHIC (original) (raw)
Related papers
Accelerating and colliding polarized protons in RHIC with Siberian snakes
We successfully injected polarized protons in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. Each snake consists of four helical superconducting dipoles which rotate the polarization by 180 • about a horizontal axis. This is the first time that polarized protons have been accelerated to 100 GeV. We report on our experiences during commissioning and operation of collider with polarized protons.
Acceleration of Polarized Protons in the AGS With Two Helical Partial Snakes
Proceedings of the 2005 Particle Accelerator Conference, 2005
The RHIC spin program requires 2~1 0 '~ protonhunch with 70% polarization. As the injector to RHIC, AGS is the bottleneck for preserving polarization: there is no space for a 111 snake to overcome numerous depolarizing resonances. An ac dipole and a partial snake have been used to preserve beam polarization in the past few years. Two helical snakes have been built and installed in the AGS. With careful setup of optics at injection and aIong the ramp, this combination can eliminate all depolarizing resonances encountered during acceleration. This paper presents the setup and preliminary results.
RHIC polarized proton operation
2011
The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP 4 . A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is 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.
Many spin-depolarizing resonances occur during the acceleration of a polarized proton beam in a high energy circular ring. The individual resonance correction technique used at the ZGS,' S a t ~ r n e , ~ KEK3 and the AGS4 becomes impractical above beam energies of about 20 GeV. Recent experiments5-lo at the IUCF Cooler Ring demonstrated that a full Siberian snake" could overcome an imperfection depolarizing re~onance,~ an intrinsic resonance6 and overlapping resonancesg by rotating the spin of each proton by 180" on each turn around the ring. However, the orbit distortions caused by a full transverse Siberian snake are especially large at injection in medium-energy accelerators such as the Fermilab Main Injector and the Brookhaven RHIC. This large orbit excursion problem could be overcome if the adiabatic turn-on of a Siberian snake does not cause depolarization. The strong higher energy depolarizing resonances could then be overcome by adiabatically turning on a full...
RHIC polarized proton operation and highlights
RHIC operation as a polarized proton collider presents unique challenges since both luminosity and spin polarization are important. Many improvements and modifications have been made since the last polarized proton operation in 2009. A 9 MHz rf system was completed that improved the longitudinal match at injection. To preserve polarization on the ramp, a new working point was chosen with the vertical tune near a third order resonance. The newly realized orbit and tune feedback systems are essential for polarization preservation. To calibrate the polarization measurement at 250 GeV, polarized protons were accelerated up to 250GeV and decelerated back to 100GeV. A vertical realignment of RHIC was conducted before the run to reduce magnet misalignment. A record peak luminosity was achieved with higher polarization at 250 GeV in this run.
Polarized proton collider at RHIC
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003
In addition to heavy ion collisions (RHIC Design Manual, Brookhaven National Laboratory), RHIC will also collide intense beams of polarized protons (I. Alekseev, et al., Design Manual Polarized Proton Collider at RHIC, Brookhaven National Laboratory, 1998 [2]), reaching transverse energies where the protons scatter as beams of polarized quarks and gluons. The study of high energy polarized protons beams has been a long term part of the program at BNL with the development of polarized beams in the Booster and AGS rings for fixed target experiments.
RHIC Performance with Polarized Protons in Run-6
AIP Conference Proceedings, 2007
The RHIC polarized proton run (Run-6) in 2006 started on February 1 and continued for 21 weeks. The Run-6 included the machine operation at different beam energies and with different orientation of beam polarization at the collision points. The machine operation at lOOGeV and 31.2 GeV provided physics data of polarized proton collisions to the STAR, PHENIX and BRAHMS experiments. Record levels of the luminosity (up to 3.5.1031 cm-* s-' peak) and proton beam polarization (up to 65%) were achieved during the lOOGeV operation. The beam polarization was preserved during the acceleration by using Siberian Snakes, based on helical magnets. The polarization orientation at STAR and PHENIX experiments was controlled with helical spin rotators. During different stages of the run the physics data were provided with longitudinal, vertical and horizontal orientations of the beam polarization at the collision points. Total luminosity integrals of 45 pb-' at 100 GeV and 0.35 pb" at 3 1.2 GeV were delivered to the experiments.
RHIC polarized proton operation in Run 12
Successful RHIC operation with polarized protons requires meeting demanding and sometimes competing goals for maximizing both luminosity and beam polarization. Run 12 consisted of four weeks of collisions with 100 GeV beams and five weeks colliding 255 GeV beams. We sought to fully integrate into operation the many systems that were newly commissioned in Run 11 as well as to enhance collider performance with incremental improvements throughout the acceleration cycle. Improvements to the luminosity were provided largely by increased intensity delivered by the polarized proton source. Increases in beam polarization came from improvements in both the injectors and in RHIC.
Status and Plans for the Polarized Hadron Collider at RHIC
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.
Polarized Proton Collisions at 205 GeV at RHIC
Physical Review Letters, 2006
The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 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 first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions.