AGS Dynamic Aperture at Injection of Polarized Protons and Helions (original) (raw)

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.

Optics Setup in the AGS and AGS Booster for Polarized Helion Beam

2014

Future RHIC physics program calls for polarized helion beam. The helion beam from the new EBIS source has a relative low rigidity which requires delicate control of injection and RF setup in the Booster. The strong depolarization resonance strength in both AGS and AGS Booster requires careful consideration of beam energy range and optics setup. Recently, the unpolarized helion beam was accelerated to 11GeV/n in the AGS. The optics with special tune path has been tested in both AGS and the Booster. The near term goal of 4×10/bunch at RHIC injection requires several RF bunch merges in both AGS and the Booster. The beam test results are presented in this paper.

Status of AC-Dipole Project at RHIC Injectors for Polarized Helions

2018

Polarized helions will be used in the eRHIC collider to collide with polarized electrons. To allow efficient transport of polarized helions in the Booster, to rigidities sufficiently high (B rho=10.8 T.m, |G gamma|=10.5) for minimizing the optical perturbations from the two partial helical dipoles in the AGS, an upgrade for overcoming depolarizing intrinsic resonances is needed. An AC-dipole is being designed to induce spin flips through intrinsic resonances. Booster AC-dipole operation will be established with protons while the polarized helion source is being completed. This paper reports the status of the project (which is now well advanced after two years of theoretical and design studies) and provides an overview of proof of principle experiments to take place after successful installation of the AC-dipole, during RHIC Run 19 with polarized proton beams.

Scanning the AC Dipole Resonance Proximity Parameter in the AGS Booster

2019

An ac dipole system will be installed in the AGS Booster in preparation for polarized helion experiments at RHIC and the future EIC. An ac dipole is a device that drives large amplitude betatron oscillations which cause all particles to sample the strong depolarizing horizontal fields in quadrupoles, resulting in a full spin flip of all particles. The amplitude of the vertical coherent oscillations induced by the ac dipole depends on the resonance proximity parameter, δm, which is the distance between the betatron tune and the modulated tune of the ac dipole. The rapid acceleration rate of the booster causes the modulated tune to decrease and δm to change. The absolute change in δm depends on the energy and the duration of the ac dipole cycle. Due to the non-zero momentum spread, particles with different momenta will have different value of δm and thus different coherent amplitudes. These effects are significant for helions crossing |Gγ | = 12 − νy and are simulated using zgoubi. A ...

Imperfection resonance crossing in the AGS Booster

Polarized helions are part of the spin physics program for the EIC, allowing collisions of polarized neutrons with polarized electrons [1, 2]. Helion imperfection resonances are 2.4 times closer than protons. Helions cross two intrinsic resonances (|Gγ| = 12 − ν y and |Gγ| = 6 + ν y) and six imperfection resonances (|Gγ| = 5, 6, 7, 8, 9, and 10) in the Booster as they are accelerated to extraction at |Gγ| = 10.5. In this same range of γ, protons cross two imperfection resonances (|Gγ|=3, and 4) and are extracted from the Booster prior to crossing the |Gγ| = 0 + ν y. Preliminary benchmarking simulations are performed using protons crossing the |Gγ| = 3 and 4 imperfection resonances, results of which are compared to experimental data. The settings used for protons are extrapolated to the helion case to show there is sufficient corrector strength to preserve polarization at each imperfection resonance up to extraction.

Simulations of AGS Boosters Imperfection Resonances for Protons and Helions

2021

As part of the effort to increase the polarization of the proton beam for the physics experiments at RHIC, a scan of orbit harmonic corrector strengths is performed in the Booster to ensure polarization transmission through the |G gamma|=3 and 4 imperfection resonances is optimized. These harmonic scans have been simulated using quadrupole alignment data and accurately match experimental data. The method used to simulate polarized protons is extended to polarized helions for crossing the |G gamma|=5 through |G gamma|=10 imperfection resonances and used to determine the corrector strength required to cross each resonance.

Transfer of a polarized proton beam from AGS to RHIC

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167), 1998

As part of the RHIC project, the RHIC machine will also be able to accelerate polarized proton beam bunches. The bunches will be extracted from the AGS machine, with kinetic energy T=25 GeV, and transfered into RHIC via the AtR transfer line . When the RHIC machine accelerates polarized protons, it will operate with two full snakes, which define the stable spin direction of a polarized proton beam circulating in each ring, along the vertical. Therefore a polarized proton beam should be injected into the RHIC machine with the stable spin direction along the vertical in order to match that of the RHIC machine. The layout of the dipole magnets of the AtR line[1] creates a dependance, on the injection energy, of the stable spin direction of a polarized proton beam injected into the RHIC machine. In this paper, the study of the stable spin direction (at the RHIC injection point) of a polarized proton beam as a function of the injection energy is presented. A modification of the AtR transfer line, which eliminates this energy dependance (within the range of proton injection energies) of the stable spin direction is also presented. 207 0-7803-4376-X/98/$10.00

Intrinsic resonances and AC-dipole simulations of 3He in the AGS Booster

Polarized 3 He collisions are part of future RHIC physics programs and of the eRHIC project. The anomalous magnetic moment of 3 He (G=-4.184) is roughly three times greater than that of protons (G=1.793), a polarized species that is already used at the Collider-Accelerator complex at BNL. Because of the higher anomolous magnetic moment and possibly injecting into the AGS at rigidities beyond 7 T • m, 3 He may have to cross depolarizing intrinsic resonances while accelerating in the Booster. To overcome these strong intrinsic resonances we look to an AC-dipole, which will need to be installed in the Booster. An AC-dipole is a magnet that induces large betatron oscillations which forces the entire bunch to experience a stronger resonance and induce a spin flip of all particles. An artificial intrinsic resonance is created, with close proximity to the original intrinsic resonance, which requires simulations to gauge what magnet strength is required. Simulations have been performed using zgoubi regarding the resonances 0 + ν y , 12 − ν y , and 6 + ν y and show that the AC-dipole is effective at overcoming these resonances. Benefits of avoiding the 0 + ν y and crossing the 12 − ν y and 6 + ν y in the Booster presents the advantage of allowing injection above the 0 + ν y in the AGS and minimizes the orbit distortions from the snakes.

SPIN COUPLING RESONANCE STUDY IN AGS

2002

In the AGS spin resonances due to coupling may account for as much as a 50 percent loss in polarization at a reduced acceleration rate. The major source of coupling in the AGS is the solenoidal snake. In the past some preliminary work was done to understand this phenomena [1], and a method to overcome these resonances was attempted . However in the polarized proton run of 2002 we sought to study more thoroughly the response of these coupled spin resonances to the strength of the solenoidal snake, skew quadrupoles and vertical and horizontal betatron tune separation. In this paper we present our results and compare them with those predicted by a modified DEPOL program .