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Very short summary of EMMA machine status

Very short summary of EMMA machine status. Shinji Machida o n behalf of commissioning team ASTeC /STFC/RAL 24 June 2010. ALICE beam. 15 MeV kinetic energy (15.5 MeV/c momentum). 20 pC , depends on tuning. 1 Hz, can be 3 Hz. 1 bunch, can be 5 bunches. Hardware restrictions.

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Very short summary of EMMA machine status

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  1. Very short summary of EMMA machine status Shinji Machida on behalf of commissioning team ASTeC/STFC/RAL 24 June 2010

  2. ALICE beam • 15 MeV kinetic energy (15.5 MeV/c momentum). • 20 pC, depends on tuning. • 1 Hz, can be 3 Hz. • 1 bunch, can be 5 bunches.

  3. Hardware restrictions • Only analog signal is available from BPM. Also only 7 pairs (E-W or N-S) at one time. • Main quadrupole magnet should be less than 260 A, enough for the present operation. • Up to 6 Hz due to the heating of septum. It is also enough. • Changing kicker amplitude shifts the kicker timing. Difficult to adjust kicker strength at crest.

  4. Injection (1) • (x, x’) at the exit of septum is not what we expected. • ~15 mm off to set angle correct and ~0.15 rad off to set position correct (number should be checked). • Septum translation and rotation can make it better, but we did not fully investigated. • Initially septum was not at design position. We found it by orbit measurement. However, it still does not give the design (x, x’).

  5. Injection (2) • Septum strength is more or less what we expected. • Kicker is only 10% or less than the design. • Small kick at kicker-1 outward. • kicker-2 kicks a beam inward. We use overshoot of kicker-2 to change the polarity. • We think we checked kicker polarity by observing beam deflection • Because (x, x’) at septum is different, kicker strength cannot be the design value.

  6. Injection (3) • Although kicker-1 kicks a beam only with a few % of design, no kicker does not make a beam go through. • The last knob which made a beam go to the end was kicker-2. • Combination of a small kicker-1 and a little stronger kicker-2 (inward) works now.

  7. Main ring • Quadrupole excitation current is a little low than the design, we think. • Nothing clear at the moment because injection was not well understood.

  8. Transverse tune • Tune measurement with 7 BPM shows • 0.12 to 0.15 for H • Around 0.13 for V • With quadrupole strength variation of -5%/+10%. • Oscillation amplitude is +/-10 mm or more. • No simple decrease vs momentum (or Q strength).

  9. Summary • EMMA is obviously running with different parameters, especially for injection, we prepared. • However, it is a set of parameters works. It was lucky we found it anyway. • Hopefully more detail report on next Thursday.

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