Train of 72 bunches that is injected into the SPS in one PS to SPS transfer.
Train of 4 × 72 or 3 × 72 bunches that is injected into the LHC in one SPS to LHC transfer.
|Beam 1 and Beam 2||Beam 1 and Beam 2 refer to the two LHC beams. Beam 1 circulates clockwise in Ring 1 and Beam 2 circulates counter clockwise in Ring 2. If colors are used for beams, Beam 1 is marked blue and Beam 2 red.|
|Beam cleaning||Removal of the large amplitude (larger than 6 sigma) particles from the beam halo. The LHC has two beam cleaning insertions: one dedicated to the removal of particles with large transverse oscillation amplitudes (IR7) and one dedicated to the removal of particles with large longitudinal oscillation amplitudes (IR3). These insertions are also referred to as the betatron and momentum cleaning or collimation insertions.|
|Beam crossing angle||Dedicated orbit bumps separate the two LHC beams at the parasitic beam crossing points of the common beam pipe of Ring 1 and Ring 2. The crossing angle bumps do not separate the beams at the IP but only at the parasitic crossing points. These orbit bumps generate an angle between the orbit of Beam 1 and Beam 2 at the IP. The full angle between the orbit of Beam 1 and Beam 2 is called the crossing angle. In IR2 and IR8 the crossing angle orbit bumps consist of two separate contributions. One external bump generated for the beam separation at the parasitic beam crossing points and one internal bump generated by the experimental spectrometer and its compensator magnets. The LHC baseline foresees vertical crossing angles in IR1 and IR2 and horizontal crossing angles in IR5 and IR8.|
|Beam screen||Perforated tube inserted into the cold bore of the superconducting magnets in order to protect the cold bore from synchrotron radiation and ion bombardment.|
|Beam types||pilot beam:
Consists of a single bunch with 0.5×1010 protons. It corresponds to the maximum beam current that can be lost without inducing a magnet quench.
Beam tailored for a maximum luminosity with reduced total beam power (i.e. increased operational margins related to beam losses and magnet quenches) and possibly smaller beam sizes (i.e. increased mechanical acceptance in terms or the transverse beam size and larger tolerances for orbit and β-beat).
Beam tailored for a high accuracy of the beam measurements with reduced total beam power (i.e. increased operational margins related to beam losses and magnet quenches).
Beam required to reach the design luminosity of L = 1034 cm-2s-1 with β* = 0.55 m (→ normalized emittance εn = 3.75 μm; Nb = 1.15 × 1011; nb = 2808).
Beam consisting of the nominal number of bunches with nominal emittances (normalized emittance of 3.75μm) and ultimate bunch intensities (I = 0.86A → Nb = 1.7×1011). Assuming the nominal value of β* = 0.55 m and 2808 bunches, the ultimate beam can generate a peak luminosity of L = 2.3 × 1034 cm-2s-1 in the two high luminosity experiments.
|BPM||Beam Position Monitor.|
|Bunch||Collection of particles captured within one RF bucket.|
|Bus bar||Main cable that carries the current for powering the magnets outside the magnet coil.|