1. Vacuum in LER and HER. First estimation for the pumping system requirements A.Variola for B.Mercier, C.Prevost, F.Letellier

2. Approximation of the pressure distribution in Cell LER #2 at SuperB under static conditions
Basic vacuum parameters
Effective pumping speed? Nature of gas ? Neg strip or coat ?, …….?
Same shape in all sections
Conductance chamber (N2 at 20°C)  43 l.m.s-1
Perimeter chamber  54 cm
Input data for VASCO program
In all sections / baked copper in situ (A. G Mathewson et al, LHC project note 21 CERN)
adjacent quadrupoles / effective pumping speed for unsatured starcell
in dipoles and drift sections antechamber
Holding pumping
Half Holding pumping
LAL Vacuum group - B. Mercier

3. Approximation of the pressure distribution in Cell LER #2 at SuperB
after in situ baked copper chamber and static conditions
With distributed pumping in dipoles and drift sections antechamber
Without distributed pumping H2 H2
Pressure (mbar)
Pressure (mbar) CO
CH4
CO2 CO
CH4
CO2
Distance (cm)
Distance (cm)

4. Approximation of the pressure distribution in Cell HER #2
at SuperB under static conditions
Basic vacuum parameters
Effective pumping speed? Nature of gas ? Neg strip or coat ?, …….?
Same shape in all sections
Conductance chamber (N2 at 20°C)  35 l.m.s-1
Perimeter chamber  28 cm
Input data for VASCO program
In all sections / baked copper in situ (A. G Mathewson et al, LHC project note 21 CERN)
adjacent quadrupoles / effective pumping speed for unsatured starcell
Distributed NEG pumping in drift sections
Distributed ion pumping in dipoles
Holding pumping
Half Holding pumping
LAL Vacuum group B. Mercier

5. Approximation of the pressure distribution in Cell HER #2 at SuperB
after in situ baked copper chamber and under static condition
With distributed ion pumping in dipoles and with distributed NEG pumping in drift sections
Without distributed pumping H2 H2
Pressure (mbar)
Pressure (mbar) CO
CH4
CO2 CO
CH4
CO2
Distance (cm)
Distance (cm)

6. Measurement of the intrinsic conductance
of the LER dipole vacuum chamber by the
Monte Carlo method (Molflow plus program)
L = 1m
Vm = m.s-1 ) average velocity for a Maxwell-Boltzman distribution
A = cm2 cross sectional area of the inlet aperture
P = 7.6 % transmission probability
Intrinsic conductance
C  50 l.s-1

7. Conclusions
1) First estimations for pumping system efficiency in HER and LER
2) W and Wo distributed pumping
3) Distributed pumping => LER = NEG, HER = Ionic.
4) Main partial pressure H2. ~few 10-10
5) LER methane stays at level with NEG (HER no due to pumping). This should be the principal responsible for beam lifetime in Gas scattering (scales linear with mass number and quadratic with the charge number of the gas)
6) Need input of photon on walls, electron on walls to determine dynamic vacuum.