  The physics programme and the design are described of a new collider for
particle and nuclear physics, the Large Hadron Electron Collider (LHeC), in
which a newly built electron beam of 60 GeV, up to possibly 140 GeV, energy
collides with the intense hadron beams of the LHC. Compared to HERA, the
kinematic range covered is extended by a factor of twenty in the negative
four-momentum squared, $Q^2$, and in the inverse Bjorken $x$, while with the
design luminosity of $10^{33}$ cm$^{-2}$s$^{-1}$ the LHeC is projected to
exceed the integrated HERA luminosity by two orders of magnitude. The physics
programme is devoted to an exploration of the energy frontier, complementing
the LHC and its discovery potential for physics beyond the Standard Model with
high precision deep inelastic scattering measurements. These are designed to
investigate a variety of fundamental questions in strong and electroweak
interactions. The physics programme also includes electron-deuteron and
electron-ion scattering in a $(Q^2, 1/x)$ range extended by four orders of
magnitude as compared to previous lepton-nucleus DIS experiments for novel
investigations of neutron's and nuclear structure, the initial conditions of
Quark-Gluon Plasma formation and further quantum chromodynamic phenomena. The
LHeC may be realised either as a ring-ring or as a linac-ring collider. Optics
and beam dynamics studies are presented for both versions, along with technical
design considerations on the interaction region, magnets and further
components, together with a design study for a high acceptance detector. Civil
engineering and installation studies are presented for the accelerator and the
detector. The LHeC can be built within a decade and thus be operated while the
LHC runs in its high-luminosity phase. It thus represents a major opportunity
for progress in particle physics exploiting the investment made in the LHC.
