Measurement of the transverse quadrupole-mode frequencies of an electron bunch in the KEK photon factory storage ring

In order to extend our knowledge on the collective beam behavior, we measured the transverse quadrupole-mode frequencies of an electron bunch in the Photon Factory storage ring at KEK. The transverse quadrupole oscillations were excited by applying oscillating quadrupole magnetic fields. The responses of the excited oscillations were recorded by detecting visible synchrotron light using a photo multiplier and a spectrum analyzer. As a result, we found remarkable dependences of the horizontal and the vertical quadrupole frequencies on the bunch current