No abstract

The microwave surface reactance of copper was measured over the temperature range from 300 to 14 K using the TE011 mode of a cylindrical cavity. The result was that with decreasing temperature the ratio of the reactive-to-resistive component remained at around 1 from 300 to 75 K, and increased to 1.32 at 14 K, in contrast to the theoretical extreme anomalous limit, equal to or higher than ∛. The discrepancy between the measured and theoretical values may be attributed to the quality of the material and the surface finishing. In this experiment an accurate measurement of the resonant frequency is important. Associated with the frequency, we discuss two thermal-expansion measurement techniques: cavity dilatometry and capacitance dilatometry. Further, the usefulness of the present data for studying high-Tc films will be mentioned.

Crab cavities have been installed in the KEKB BFactory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the prediction of simulation. Proceedings of PAC07,

No abstract

The deflecting modes of the 805 MHz side-coupled cavity structure with the relativistic factor 0.566 are studied. Our main concern is the dispersion properties among different configurations of side-coupling cells and their interpretations. It is shown that the ninety degree side-coupling cell configuration, so to speak, the Mickey Mouse configuration has a merit in reducing the HEM1 passband. Another concern is the magnitude of the transverse coupling impedance around the synchronization condition. It is shown that the existence of the coupling cell introduces the nonuniformity of the deflecting mode and gives differ.:nt impedance relative to the beam axis and that the coupling impedance at 7t/10 exceeds 50 Mn/m if the quality value of the mode is around 12000.