1. Vacuum status at KEKB
Junji Haba

2. KEKB Vacuum system

3. Vacuum monitoring

4. HER vacuum characteristics
Dependence on HER current is clear.
<p> ~ 0.3 (0A)  1.2 (1.3A) x10-7Pa
1nTorr (PEPII) =1.3 x 10-7 Pa (KEKB)
Far from “base pressure dominance”
Not always simple linear relation
Some show a clear thermal behavior
Beam life time is a function not only of pressure but also luminosity or beam-beam effect.

5. 2004 June

6. Heat up at the
feed back kicker
structure
Discharge starts
around 0.9A at
septum?

8. Life time is predetermined by luminosity

9. Beam-beam also affects the lifetime
LER current
HER beam size vs LER current
HER life and beam size

10. LER vacuum characteristics
Current dependence is clear
<p>~ 0.2 (0A)  0.8 (1.6A) x10-7Pa
Thermal behavior everywhere we have the parts with a special internal shape like GV, crotches, injection chamber etc.