Chromaticity compensation-Booster sextupoles

The current Booster lattice is studied in the context of full chromaticity compensation in the presence of the sextupole fields generated by the combined function magnets. The sextupole excitation at various energies, found from chromaticity measurements and Booster lattice analysis, was compared with magnetostatic multipole calculations. Both results agree very well and they are consistent with the original design specifications. Two families of correcting sextupole magnets are employed to compensate the sextupole excitations and to adjust the chromaticity (in both planes) to a desired value, which is set by head-tail stability consideration. Analysis of the required correcting sextupole strengths is carried out along the momentum ramp with the measured sextupole excitations of the combined function magnets. The results of our calculation give quantitative insight into the requisite performance of the sextupole magnets. It calls for much stronger sextupole strengths-at the level which can no longer be supported by the present correcting sextupole magnet design