We had the 6th IP-BPM meeting at 15:00-16:00, 27th July 2006, 425, 3-gokan, KEK.
Participants: P.Doublet, Y.Honda and T. Tauchi
Philippe reported his work for last two weeks. His presentation is here and the electronics test summary report ( here )
Cavity design for an ILC-like beam (2)
He continued to design a new cavity based on the present rectangular IP-BPM. The design goal is a cavity with QL=400 for the ILC-like beams with shorter bunch length.
First, he optimized the slot position for good signal transmission without hitting the beam pipe by the wave-guide. The slot position is defined by a distance between two centers of the cavity and the slot in x direction. It was 17mm. Resonant structure of signals largely depends on the slot x-dimension, while it has less dependence on the y-dimension. The dipole and 2nd monopole signals become to overlap with larger x-dimension. So, he chose 12mm for the x-dimension. The wave guide position was chosen for maximum transmission without hitting the beam pipe, while it does not change the frequencies.
He has a question, i.e. is it good to only survey S-parameter (transmission) ... ? His own answer is " OK until now, the Q-value will be adjusted with the wave guides" .
Honda commented that the wave guide can not change the Q-value but matching the signals for readout. Major parameter must be the slot dimension for the Q-value. QL can be calculated by f/Δf, while perfect conductor has been assumed in the MAFIA calculation; i.e. external Q is equal to loaded Q.
He will follow the above suggestion for small QL .
After he summarized the electronics test results, he concentrated on writing a final report both in French and English. The reports will be completed before he leave here.
We will have the next meeting on 3rd August 2006, 10:00 -. room 222 at 3-gokan.