  We have used measurements by the Fermi Large Area Telescope (LAT) to study
the interstellar gamma-ray emission in a region of the second Galactic
quadrant, at 100 deg < l < 145 deg and -15 deg < b < 30 deg. This region
encompasses the prominent Gould-Belt clouds of Cassiopeia, Cepheus, and the
Polaris flare, as well as large atomic and molecular complexes at larger
distances in several spiral arms. The good kinematic separation in velocity
between the local, Perseus, and outer arms, and the presence of massive
complexes in each, make this region very well suited to probe the gamma-ray
emission from the interstellar medium beyond the solar circle. The
unprecedented sensitivity and angular resolution of the LAT provide improved
constraints on the gradient of the cosmic-ray densities and on the increase of
the CO-to-H2 conversion factor, Xco, in the outer Galaxy.

High Energy Astrophysical Phenomena