106 MHz cavity for improving coalescing efficiency in the Fermilab Main Ring

In Fermilab´s Main Ring a fast coalescing scheme called Snap coalescing has replaced the slower adiabatic coalescing. In Snap coalescing the adiabatic voltage reduction to reduce the dp/p of the bunch has been replaced with a quarter of a synchrotron period rotation in a 53-MHz bucket. A 106 MHz second harmonic cavity has been constructed to help linearize the 53 MHz rotation and reduced the minimum achievable dp/p. The effect of the second harmonic cavity on the 53 MHz rotation and the coalescing efficiency will be described