The high nominal luminosity of the LHC requires a large number of bunches spaced by about 7.5 m. To prevent more than one head-on collision in each interaction region, a crossing angle of 0.285 mrad is necessary. A side effect of this crossing angle is the increase of the effective transverse beam cross-section, thereby decreasing the luminosity by some 16%. For the LHC luminosity upgrade, depending on the focusing scenarios, this loss significantly increases and largely offsets the potential gain of a stronger focusing. In this paper we analyze a strategy to circumvent this difficulty, based on an early beam separation using small dipoles placed at a few meters from the interaction point. From the beam dynamics point of view, the essential constraint is to control the long-range beam–beam interactions in a scenario where the normalized beam separation is not constant.
[1]
R. Schmidt,et al.
Beam-beam effects and high luminosity operation in the SPS proton antiproton collider
,
1986
.
[2]
Frank Zimmermann,et al.
Weak-strong beam-beam simulations for the Large Hadron Collider
,
1999
.
[3]
Frank Zimmermann,et al.
Estimates of diffusion due to long-range beam-beam collisions
,
2002
.
[4]
F. Zimmermann,et al.
Study of Long-Range Collisions and Wire Compensation for Tevatron Run-II
,
2004
.
[5]
J. Koutchouk.
POSSIBLE QUADRUPOLE-FIRST OPTIONS WITH β * ≤ 0 . 25
,
2005
.
[6]
F. Zimmermann,et al.
Possible Scenarios for an LHC Upgrade
,
2005
.