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Helical magnets Siberian snakes. I.Koop, A.Otboyev, P.Shatunov Yu.Shatunov Budker Institute for Nuclear Physics Novosibirsk. Praha- Dubna SPIN2013. yoke. coil. Helical magnet. cm. yoke. coil. cm. B z. B x. B y. kGs. kGs. kGs. cm. cm. cm. cm. cm. cm.
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Helical magnets Siberian snakes I.Koop, A.Otboyev, P.Shatunov Yu.Shatunov Budker Institute for Nuclear Physics Novosibirsk Praha- Dubna SPIN2013
yoke coil Helical magnet cm yoke coil cm
Bz Bx By kGs kGs kGs cm cm cm cm cm cm Transverse cross section of the field map
Bx By Helix field components on the axis(λ=2.5 m)
Particle and spin motion equations in the Cartesian frame (Bρ is a rigidity)
e2 S e3 -k e1 Spin in helical magnet(zero approximation) For protons (a=1.793) p=1 by b0λ=19.6 Tm
Siberian snakes and spin rotators • Spin rotation • No orbit disturbing and coupling outside α3 α4 α1 α2 R3 R4 R1 R2 p3 p4 p1 p2 rotators snakes . R1=R4; R2 =R3 p1=-p4; p2 =-p3
Siberian Snake in RHIC 4 superconducting helical dipoles: Magnetic field 4T, length 2.4 m each with 360° twist, coil inner aperture 100 mm.
RHIC polarization E=255 GeV L=5·1031cm-2s-1 S~50%
Snake from 2 helical magnets ξ = - ξ = + By Bx z (cm)
Optimal particle trajectory y x (cm) z (cm)
Spin trajectory S(0)=Sy→ -Sy Sz Sy Sx z (cm)
Spin trajectory S(0)=Sz→ -Sz Sz Sy Sx z (cm)
corrector corrector Helix 3.4 m (λ=0.75 m) Partial snakes(field on axis)
corrector corrector Helix 3.4 m (λ=0.75 m) Proton’s trajectory in the snake E=25 ГэВ x
ACCELERATION OF POLARIZED PROTONS IN THE AGS WITH TWOHELICAL PARTIAL SNAKES H. Huang, L.A. Ahrens, M. Bai, K. Brown, E. D. Courant, C. Gardner, J.W. Glenn, R. C. Gupta, A.U. Luccio, W.W. MacKay, V. Ptitsyn, T. Roser, S. Tepikian, N. Tsoupas, E. Willen, A. Zelenski,K. Zeno, BNL, Upton, USAM. Okamura, J. Takano, Radiation Laboratory, RIKEN, Saitama, Japan, F. Lin, Indiana University, Bloomington S=70% 6% AGS 13%
l r ⊗ ⊙ NICA polarization(protons 10 GeV) Helical magnet snake B=4 T; L=10 m Δx~Δz~1-2 mm Solenoid snake B=4T; L=10 m (coupling?)
longitudinal IBS diffusion rate (s-1) e L transverse NICA polarization + luminosity
“Rotating” quads angle I1/I2
bunches. space-charge effect ● Limitations: instabilities in electron cooler: ● beam-beam effect ● Luminosity considerations Coulomb scattering cross-section: ● Assumptions: ● ● round beams ● ● electron cooling will squeeze beams to the space charge limit
Np=1011 Ek (GeV) Luminosity considerations
Conclusion Let’s do it! Thanks for attention!