Studies of Decay and Snapback Effects on LHC Dipole Magnets

LHC model magnets have dynamic field imperfections of various nature. Two effects of particular importance are field component decay during injection and ''snapback'' during the first few seconds of acceleration, which happens over typically 15 to 20 mT. The dynamic behaviour of the model magnets was measured as a function of several parameters in the operation cycle and powering history. We demonstrate how the systematic variation of only one single operation cycle parameter can affect the behaviour of the sextupole component.