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Article
Title	Betatron Tune Spread Generation and Differential Chromaticity Control by Octupole at Tevatron
Author(s)	Ivanov, Petr M ; Alexahin, Yuri ; Annala, Jerry ; Lebedev, Valeri
Affiliation	(Fermilab, Batavia, Illinois)
Publication	2005
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.2756
Subject category	Accelerators and Storage Rings
Abstract	Application of octupoles for Landau damping of the unstable head-tail modes requires careful consideration at their combination into separate families to insure maximum effectiveness and avoid degradation of the dynamic aperture due to the non-linear magnetic fields. Existing octupolar magnets around the machine have been arranged into four functional families with individual power supplies. Two of these families generate betatron tune spreads in the vertical and horizontal planes whereas the other two control the differential chromaticity between the proton and antiproton helices. The calculated effect on tunes and chromaticity is compared with direct measurements. Analytical formulas for betatron tune spectral density functions are presented.