  The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e+e-
collider under development. For an optimal exploitation of its physics
potential, CLIC is foreseen to be built and operated in a staged approach with
three centre-of-mass energy stages ranging from a few hundred GeV up to 3 TeV.
The first stage will focus on precision Standard Model physics, in particular
Higgs and top-quark measurements. Subsequent stages will focus on measurements
of rare Higgs processes, as well as searches for new physics processes and
precision measurements of new states, e.g. states previously discovered at LHC
or at CLIC itself. In the 2012 CLIC Conceptual Design Report, a fully optimised
3 TeV collider was presented, while the proposed lower energy stages were not
studied to the same level of detail. This report presents an updated baseline
staging scenario for CLIC. The scenario is the result of a comprehensive study
addressing the performance, cost and power of the CLIC accelerator complex as a
function of centre-of-mass energy and it targets optimal physics output based
on the current physics landscape. The optimised staging scenario foresees three
main centre-of-mass energy stages at 380 GeV, 1.5 TeV and 3 TeV for a full CLIC
programme spanning 22 years. For the first stage, an alternative to the CLIC
drive beam scheme is presented in which the main linac power is produced using
X-band klystrons.
