  Measurements of the cross sections of the reference processes seen by the
ALICE trigger system were obtained based on beam properties measured from van
der Meer scans. The measurements are essential for absolute cross section
determinations of physics processes.
  The paper focuses on instrumental and technical aspects of detectors and
accelerators, including a description of the extraction of beam properties from
the van der Meer scan. As a result, cross sections of reference processes seen
by the ALICE trigger system are given for proton-proton collisions at two
energies; $\sqrt{s}$=2.76 TeV and 7 TeV, together with systematic uncertainties
originating from beam intensity measurements and other detector effects.
Consistency checks were performed by comparing to data from other experiments
in LHC.
