1. Electron cloud measurement in Cu/Al chambers with/without TiN coating at KEKB positron ring 2010.2.23 ILC DR Working Group Meeting Kyo Shibata (KEK)

2. Test chambers with/without TiN coating have been installed into KEKB positron ring (Low Energy Ring, LER), and the electron cloud densities in them have been measured. Test chambers (circular duct with a diameter of 94 mm): 1. Copper chamber (Cu, OFC C10100) 2. Copper chamber with TiN coating (Cu+TiN) 3. Aluminum alloy chamber (Al, 5052) 4. Aluminum alloy chamber with TiN coating (Al+TiN) – Thickness of TiN coating : 200 nm 2010/2/232ILC DR Working Group Meeting CuCu + TiNAl + TiN

3. KEKB LER (positron ring) : – Energy : 3.5 GeV – Beam current :  1600 mA – Number of bunch :  1585 (  1 mA/bunch,  10 nC/cunch) – Bunch spacing : 6 ns – Bunch length : 6 mm All test chambers were installed into the same location. – Straight section – Number of Photon : 3  10 12 photons /s/m/mA – Drift space – No solenoid field 2010/2/233ILC DR Working Group Meeting Test chamber (Al) Electron monitor

4. Electron cloud density near the bunch were measured by a electron monitor with RFA. – By selecting high energy electrons, the density near the bunch can be estimated. 2010/2/234ILC DR Working Group Meeting Electron monitor Conceptual drawing of the density measurement

5. Electron cloud density in the bare Al chamber is much larger than that in Cu chamber. TiN coating is effective for both Cu and Al chambers. 2010/2/235ILC DR Working Group Meeting Al Cu Al + TiN Cu + TiN K. Kanazawa