  We consider theoretically the relaxation of electron spin component parallel
to the growth direction in multiple (110) GaAs quantum wells. The sources of
spin relaxation are the random Rashba spin-orbit coupling due to the electric
field of donors and spin-flip collisions of electrons from different quantum
wells. We show that the screening of the Coulomb forces at low temperatures
leads to a very strong enhancement of the spin relaxation time. In a degenerate
electron gas the Pauli blocking suppresses the electron-electron collisions,
and the leading spin relaxation mechanism comes from the field of donors. If
the electron gas is nondegenerate the electron-electron collisions and
scattering by the ionized donors give similar contributions to the relaxation
rate.
