648
K. Hübner et al.
Apart from the DS the insertions comprise the following sections, given in order
from the interaction point:
• A 31 m long superconducting low-β triplet assembly operated at 1.9 K and
providing a nominal gradient of 215 T/m.
• A pair of 9.45 m long superconducting separation/recombination dipole magnets
separated by approximately 66 m.
• Four matching quadrupole magnets. The first two quadrupole magnets following
the separation dipole magnets, Q4 and Q5, are wide aperture magnets operating at
4.5 K and yielding a nominal gradient of 160 T/m. The remaining two quadrupole
magnets are normal aperture quadrupole magnets operating at 1.9 K with a
nominal gradient of 200 T/m.
The triplet quadrupoles are powered in series and are followed by the separation/recombination dipoles D1 and D2, which guide the beams from the IP into two
separated vacuum chambers. Q4, Q5, Q6, Q7, Q8, Q9 and Q10 are individually
powered magnets. The aperture of Q4 is increased to provide sufficient aperture for
the crossing-angle separation orbit. The aperture of Q5 left of the IP is increased
to provide sufficient aperture for the injected beam. The injection septum MSI is
located between Q6 and Q5 on the left-side of the IP and kicks the injected beam
in the horizontal plane towards the closed orbit of the circulating beam (positive
deflection angle). The injection kicker MKI is located between Q5 and Q4 on the
left-hand side of the IP and kicks the injected beam in the vertical plane towards the
closed orbit of the circulating beam (negative deflection angle). In order to protect
the cold elements in case of an injection failure a large absorber (TDI) is placed
15 m upstream from the D1 separation/recombination dipole left from the IP. The
TDI absorber is complemented by an additional shielding element 3 m upstream of
the D1 magnet and two additional collimators installed next to the Q6 quadrupole
magnet. In order to obtain an optimum protection level in case of injection errors
the vertical phase advance between MKI and TDI must be 90 ◦ and the vertical
phase advance between the TDI and the two auxiliary collimators must be an integer
multiple of 180 ◦ ± 20 ◦ .
The matching section extends from Q4 to Q7 and the DS extends from Q8 to
Q11. In addition to the DS, the first two trim quadrupoles of the first arc cell (QT12
and QT13) are also used for the matching procedure. All magnets of the DS are
equipped with a beam screen. The magnets left and right from the IP up to Q7
inclusive are placed symmetrically with respect to the IP. The positions of Q8, Q9
and Q10 left and right from the IP differ by approximately 0.5 m with respect to the
IP due to the limited space in the DS.
10.6.2.6 LSS8
IR8 houses the LHCb experiment and the injection elements for Beam 2. The small
β-function values at the IP are generated with the help of a triplet quadrupole
assembly. At the IP, the two rings share the same vacuum chamber, the same low-
K. Hübner et al.
Apart from the DS the insertions comprise the following sections, given in order
from the interaction point:
• A 31 m long superconducting low-β triplet assembly operated at 1.9 K and
providing a nominal gradient of 215 T/m.
• A pair of 9.45 m long superconducting separation/recombination dipole magnets
separated by approximately 66 m.
• Four matching quadrupole magnets. The first two quadrupole magnets following
the separation dipole magnets, Q4 and Q5, are wide aperture magnets operating at
4.5 K and yielding a nominal gradient of 160 T/m. The remaining two quadrupole
magnets are normal aperture quadrupole magnets operating at 1.9 K with a
nominal gradient of 200 T/m.
The triplet quadrupoles are powered in series and are followed by the separation/recombination dipoles D1 and D2, which guide the beams from the IP into two
separated vacuum chambers. Q4, Q5, Q6, Q7, Q8, Q9 and Q10 are individually
powered magnets. The aperture of Q4 is increased to provide sufficient aperture for
the crossing-angle separation orbit. The aperture of Q5 left of the IP is increased
to provide sufficient aperture for the injected beam. The injection septum MSI is
located between Q6 and Q5 on the left-side of the IP and kicks the injected beam
in the horizontal plane towards the closed orbit of the circulating beam (positive
deflection angle). The injection kicker MKI is located between Q5 and Q4 on the
left-hand side of the IP and kicks the injected beam in the vertical plane towards the
closed orbit of the circulating beam (negative deflection angle). In order to protect
the cold elements in case of an injection failure a large absorber (TDI) is placed
15 m upstream from the D1 separation/recombination dipole left from the IP. The
TDI absorber is complemented by an additional shielding element 3 m upstream of
the D1 magnet and two additional collimators installed next to the Q6 quadrupole
magnet. In order to obtain an optimum protection level in case of injection errors
the vertical phase advance between MKI and TDI must be 90 ◦ and the vertical
phase advance between the TDI and the two auxiliary collimators must be an integer
multiple of 180 ◦ ± 20 ◦ .
The matching section extends from Q4 to Q7 and the DS extends from Q8 to
Q11. In addition to the DS, the first two trim quadrupoles of the first arc cell (QT12
and QT13) are also used for the matching procedure. All magnets of the DS are
equipped with a beam screen. The magnets left and right from the IP up to Q7
inclusive are placed symmetrically with respect to the IP. The positions of Q8, Q9
and Q10 left and right from the IP differ by approximately 0.5 m with respect to the
IP due to the limited space in the DS.
10.6.2.6 LSS8
IR8 houses the LHCb experiment and the injection elements for Beam 2. The small
β-function values at the IP are generated with the help of a triplet quadrupole
assembly. At the IP, the two rings share the same vacuum chamber, the same low-