Measurements of field decay and snapback effect on Tevatron dipole magnets

The performance of Fermilab\´s Tevatron accelerator, currently in its Run II stage, is degraded by beam loss and emittance dilution during ramping from injection to collision energy. This could be related in part to insufficient compensation of dynamic effects such as the decay of the magnetic field in the dipoles during the dwell at injection and the following so-called snapback during the first few seconds of the energy ramp. The two effects are closely related and depend on the powering history of the magnets. Dynamic effects, which were originally discovered at the Tevatron [D.A. Finley et al., "Time dependent chromaticity changes in the Tevatron", Proceeding pf Part. Acc. Conf., Washington DC, 1987.], were investigated on Tevatron magnets in various past measurement campaigns in the 1980s and later in 1996 [G. Annala et al., "Tevatron Dipole Measurements at MTF", http://www-bdnew.fnal.gov/tevatron/adcon/magnets.html, P. Bauer et al., "Analysis of the b2 Correction in the Tevatron", These Proceedings]. This paper reports on the most recent measurements performed on an additional set of Tevatron magnets.