A study of Polarized Proton Acceleration in j-parc a. U. Luccio, M. Bai, T. Roser
tarix 27.12.2018 ölçüsü 489 b. #87506
A.U.Luccio, M.Bai, T.Roser Brookhaven National Laboratory, Upton, NY 11973, USA A.Molodojentsev, C.Ohmori, H.Sato High Energy Accelerator Research Organization, Tsukuba, Ibaraki, Japan H.Hatanaka Layout of J-PARC for polarized proton acceleration Optically Pumped Polarized Ion Source: 1012 H- per 0.5 ms pulse and > 5 Hz rep. rate, 85% polarization (similar to KEK-TRIUMF-BNL OPPIS) Bunch emittance: ~ 5 rad and 0.3 eVs for 2 1011 protons (required for polarized beam acceleration) Linac: No depolarization RCS (25 Hz, y = 6.35, P = 3, Ekin = .18 … 3 GeV, G = 2.2 … 7.5) 5 imperfection resonances; harmonic correction needed for G = 7 Intrinsic resonances: G = 2.65 (9- y), 3.35 (-3+ y), 5.65 (12- y), 6.35 (0+ y) Full spin flip with rf dipole: 20 Gm gives > .99 spin-flip (seems feasible) Avoid depolarization with tune jump: y = 0.2 in 6 turns large aperture ferrite quadrupoles with fast pulsing power supplies (difficult) Issues of accelerating polarized protons in Main Ring Beam energy: 3 50 GeV (G = 7.5 97.5) Design working point: x = 22.34; y = 20.27 Many imperfection resonances Strong intrinsic resonances No space for full snake installation Solution of accelerating polarized protons in Main Ring 12 particles at 4 rad (1.5 beam sigma) 12 particles at 4 rad (1.5 beam sigma) Two 30% synthetic snakes Working point: Main Ring Partial Snake AGS type of cold snake magnetic field strength: 3.4 Tesla snake strength 30% (540 spin rotation angle) at injection and gets weaker at higher energy according to: Matching of the INSA with snake at the energy =11 Solution of Correcting Quadrupoles Conclusion Possible to accelerate polarized protons of 10 mm-mrad in the J-PARC Main Ring using two 30% partial snakes of AGS type. The perturbation on the MR optics from snakes is significant at low energy. This can be minimized by using a correcting quadrupole doublet each at the entrance and exit of each snake. Tracking with the code Spink using synthetic snakes with variable strength and a static lattice shows good polarization survival. Dostları ilə paylaş:
