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Spin Flipper

Spin Flipper. M. Bai, T. Roser, A. Brava, G. Bunce, A. Luccio, R. Gill, P. Oddo Thanks for the help from: Itaru, Larry Hoff, Brian Oerter, JoeP. Summary of spin tune measurement experiment during RUN06 Plan for commissioning spin tune measurement during RUN07 Outlook to spin flipping.

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Spin Flipper

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  1. Spin Flipper M. Bai, T. Roser, A. Brava, G. Bunce, A. Luccio, R. Gill, P. Oddo Thanks for the help from: Itaru, Larry Hoff, Brian Oerter, JoeP • Summary of spin tune measurement experiment during RUN06 • Plan for commissioning spin tune measurement during RUN07 • Outlook to spin flipping

  2. Summary of the spin tune measurement experiment • Goal of the experiment • Use the ac dipole to induce a coherent spin precession in the horizontal plane. The turn by turn asymmetry measured by CNI polarimeter can be transformed into the rotating frame to give the coherent precession amplitude in the horizontal plane • Results • Took data at injection and store(100 GeV) without detune snakes • Observed full depolarization at injection by setting the ac dipole tune at 0.498 • Encouraging data but not conclusive

  3. Summary of the spin tune measurement experiment

  4. Summary of the spin tune measurement experiment

  5. Summary of the spin tune measurement experiment

  6. Summary of the spin tune measurement experiment

  7. Last spin tune measurement experiment in RUN06 • During the last APEX session, we took data for different ac dipole tune from 0.499 to 0.492. However, what we observed is full depolarization at all the ac dipole tune settings. The offline data analysis of the ac dipole current readback suggests that the actual ac dipole tune was stuck at 0.498 even when it was asked to oscillate at different tunes Sample frequency: 30Hz Data from Peter Oddo

  8. Problems during the spin tune measurement experiment • system problem • Low level glitch causes power supply trip for long ac dipole pulse • Power supply gets tripped off around 80 Gauss-m • Lack of online current readback for monitoring whether the magnet is providing what we request • Conceptual problem • Rotating ac field vs. oscillating field

  9. How to construct a rotating field with ac dipoles -167.493o Ac dipole 2 208.03o Ac dipole 1 # of spin precessions between the two ac dipoles

  10. Plan for the spin tune measurement for RUN07 • Fix the low level waveform generator problem • Design/commission an online ac dipole current/frequency readback data acquisition/logging • Exam the ps tripping issue • If time permits, add an ac dipole after D0 to get a rotating field

  11. Outlook of spin flipping in the presence of two snakes • Requirement on the spin flipper for RHIC • Spin flipping with beam spin tune at ½ • This can only be achieved by an induced resonance with rotating axes • Minimum effect on the beam orbital motion • With the two ac dipoles separated by DX and D0, a resonance with rotating axes can be induced by keeping both ac dipoles’ amplitude at a relative small value and slowly sweep their tune through ½ • Single particle • Spin tune = 0.5 • Spin flipper: • Amplitude: 20 Gauss-m • Tune: 0.49 -> 0.51 • Sweep in half million turns • Tolence on the error of phase between the two ac dipoles: • ~1 degrees

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