  Gray molasses is a powerful tool for sub-Doppler laser cooling of atoms to
low temperatures. For alkaline atoms, this technique is commonly implemented
with cooling lasers which are blue-detuned from either the D1 or D2 line. Here
we show that efficient gray molasses can be implemented on the D2 line of 40K
with red-detuned lasers. We obtained temperatures of 48(2) microKelvin, which
enables direct loading of 9.2(3)*10^6 atoms from a magneto-optical trap into an
optical dipole trap. We support our findings by a one-dimensional model and
three-dimensional numerical simulations of the optical Bloch equations which
qualitatively reproduce the experimentally observed cooling effects.
