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PS RF Developments for Pb 54+ Ions in 2007

PS RF Developments for Pb 54+ Ions in 2007. S. Hancock. Context. We are required to provide the early beam for the SPS, but this and advancing the nominal beam requires some problem solving. In a previous “to do” list it was noted that:

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PS RF Developments for Pb 54+ Ions in 2007

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  1. PS RF Developments for Pb54+ Ions in 2007 S. Hancock

  2. Context We are required to provide the early beam for the SPS, but this and advancing the nominal beam requires some problem solving. In a previous “to do” list it was noted that: • There is insufficient pick-up sensitivity to permit the radial loop to be closed until ~100ms after injection. This is the most probable cause of the ~20% losses seen at the start of acceleration. It is proposed to remove 12dB of attenuation during the next shutdown. • Given that the beam lifetime issues of the fixed-target era did not recur, the intermediate plateau could be lowered. This would facilitate the rf gymnastics of the nominal scheme (lower energy  longer bunches, higher synchrotron frequency). Proposal: 0.31 0.17 T, which coincidentally corresponds to 3.57 GeV/c proton equivalent. It should be deferred until the low-energy performance of the radial loop has been verified. • Control of the relative phasing between the different harmonic components of the 10MHz system is an issue that must be addressed (cf., triple splitting for LHC protons). All MHSs receive a common clock that is tagged at the revolution frequency. A consequence of the common clock is that there is no relative phase control of the harmonic components during triple splitting, ion gymnastics and batch compression. New tagging hardware is being built to overcome this. Setting-up could be delicate, but debugging will use protons. • Several more MDs will be required to complete the work on the nominal beam.

  3. Radial Pick-up Sensitivity In 1999, -12 dB capacitive dividers were introduced before the cathode followers of pick-ups 83 and 93 in order to increase the maximum intensity that can be handled by the H16LI beam control (to somewhere in the region of 1E11 ppb). This attenuation has now roughly been halved and a large difference in overall gain between the two pick-ups has been eliminated. It has also been established that the lack of sensitivity suffered last year was not due to insufficient bandwidth. However, the net effect on the beam – for both the maximum intensity of protons and the minimum intensity of ions – remains to be seen.

  4. Batch Expansion and Bunch Splitting (Simulation)

  5. Local Oscillators In principle, it should be possible to minimize the complexity of the nominal beam control by reducing the number of local oscillators used in the loop processing to just two: h=12 and h=21. This was not done last year because, out of expediency, h=16 was used at injection in the same way as for the early beam. The MDs required to establish if the h=16 LO can be eliminated are likely to conflict with the simultaneous delivery of the early beam.

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