2.3 Shifting of the HOM Frequencies to the Closest Dangerous Resonant Frequency

A monopole HOM impedance can contribute the maximum growth rate to a symmetric longitudinal mode when the HOM frequency falls on a revolution harmonic upper-synchrotron sideband. Similarly, a dipole HOM impedance can contribute the maximum growth rate to a symmetric transverse mode when the HOM frequency falls on a revolution harmonic lower-betatron sideband. An optional data column may be included in the HOM definition file (see section 4) as a flag to force selected HOM frequencies onto dangerous resonances. Because of the relatively low probability for HOM frequencies to hold exactly these resonant values, this option is mostly useful in checking the calculated growth rates against those obtained in hand calculations.