Vacuum constraints
static density of 10-7 mbar ? 2 m (H2 300K) ?
0.01 % of LHC limit for integrated density
( 2.7 106 cm ? 1.6 109 molecules/cm3 )
- beam stability: dynamic effects must be taken into account
- 10-7 mbar ? 1.2 m (H2 300K) ? 1.5 % of LHCb nominal luminosity
Difficult to achieve with silicon detectors, electronics and signal wires
directly in LHC vacuum ! ? differential pumping.