Saito K.

Paper	Title	Page
TU202	Gradient Yield Improvement Efforts for Single and Multi-Cells And Progress for Very High Gradient Cavities	82
	K. Saito KEK
	ILC cavity specification was fixed at the ILC Snowmass workshop 2005. However, after the workshop DESY developed a low production yield problem on the TTF cavities. GDE R&D board has built a task force to solve the problem. This task force proposed S0/S1 studies and accepted by GDE. DESY has nearly demonstrated the 35MV/m high gradient module, even the gradient yield is still low. The other major laboratories, FNAL, JLAB and KEK also started the R&D. S0 study has started in JLAB. STF activity has stated in KEK. In these activities, 9-cell cavity result is accumulated. S0 single cell program has been started and very promising recipe has been developed. We have a remarkable improvement with high gradient in these two years. High gradient shapes: Low loss or Re-entrant has brought a breakthrough. Now the world record is 60MV/m. In this paper these worldwide activities are presented.
	Slides(PDF)
TUP10	High Reliable Surface Treatment Recipe of High Gradient Single Cell SRF Cavities at KEK	125
	F. Furuta, K. Saito, T. Saeki, H. Inoue, Y. Morozumi, Y. Higashi, T. Higo KEK
	We have continued the series tests of single cell superconducting cavities at KEK. These tests are aimed at establishing a high yield production of surface treatment that would reliably allow cavities to reach gradients in excess of 45 MV/m with high Q in vertical tests. The cavity shape is all of the KEK Low Loss design. Early results from this series test demonstrated that reaching gradients as high as 50 MV/m was feasible. However, the initial yield was of order 50 %. In order to increase the yield we have modified our surface preparation followed an established KEK procedure (KEK-WG5 recipe). We have succeeded to reach the >95 % yield with gradient of > 45 MV/m.
TUP15	Multipacting Study of ICHIRO End Cavity	142
	I. Hwang, E. -S. Kim CHEP, Kyoungpook National University J. Hong POSTECH Y. Morozumi, K. Saito KEK
	High gradient superconducting RF cavity named Ichiro type in KEK is developing as the Alternatives Configuration Document for the international linear collider. Multipacting is one of the most serious limitations to achieve high gradient. Several simulation research found out that multipacting at the tapered beam pipe is too strong. We investigated multipacting effects in various end cavities with beam tube and compared with experiments.
WEP45	The first processing of capacitive-coupling coupler at room temperature in a cryomodule at STF	587
	T. Saeki, H. Matsumoto, S. Kazakov, F. Furuta, K. Saito, Y. Higashi, T. Higo, H. Inoue, Y. Morozumi, M. Sato, H. Yamaoka KEK J. Hong PAL J. Zhai IHEP, CAS
	We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of ILC accelerator. In the beginning of year 2007, we installed one TESLA-like 9- cell cavity and one high-gradient Low-Loss (LL) type 9- cell cavity into cryomodules at STF. For the LL 9-cell cavity, an Capacitive-Coupling (CC) input-coupler, a ballscrew tuner and other peripherals were assembled with the cavity. The assembled cavity package was installed with thermal shields and so on into a cryomodule. After the installation, we performed the first processing of Capacitive-Coupling (CC) input-coupler in a cryomodule at the room-temperature. We achieved the power of 250 kW with the pulse-width of 1.5 msec at the repetition rate of 5 pps. This presentation describes about the assembly of a CC coupler and a high-gradient LL 9-cell cavity in a clean room and the processing of the CC coupler at the room temperature in a cryomodule.
WEP66	High pressure rinsing system studies	664
	D. Sertore, M. Fusetti, P. Michelato, C. Pagani INFN Milano-LASA T. Higo, J. Hong, K. Saito KEK G. Ciovati, T. Rothgeb JLab A. Matheisen, N. Krupka DESY
	High pressure rinsing (HPR) is a key process for the surface preparation of high field superconducting cavities. HPR water jets used in different laboratories have been characterized measuring the transferred momentum between the water jet and a target connected to a load cell. The information taken during these measurements, combined with HPR process parameters, allow calculating new significant measurable variables such as the jet power, the deposited energy on the cavity surfaces and the pressure.
WEP69	MgB2 thin films on Nb cavity by pulse laser deposition	672
	S. Mitsunobu, S. Inagaki, H. Nakanishi, K. Saito, M. Wake, M. Yoshida KEK M. Fukutomi NIMS
	The large efforts have been concentrated on Nb cavities for International Linear Collider (ILC). The maximum accelerating field gradient of Nb cavities is limited about 50 MV/m due to Hcsh. MgB2 (MgB2) have higher Tc than Nb and expected to have higher Hcsh. Thin films of MgB2 on Nb is useful to increase future ILC energy upgrading. At KEK, the preliminary test of thin films on Nb by Pulse Laser Deposition(PLD) method have been started and initially the direct deposition of MgB2 film on Nb discs and single cell cavity was studied.