  We calculate the location of the magnetically-inactive dead zone in the
minimum-mass protosolar disk, under ionization scenarios including stellar
X-rays, long- or short-lived radionuclide decay, and energetic protons arriving
from the general interstellar medium, from a nearby supernova explosion, from
the disk corona, or from the corona of the young star. The disk contains a dead
zone in all scenarios except those with small dust grains removed and a
fraction of the short-lived radionuclides remaining in the gas. All the cases
without exception have an "undead zone" where intermediate resistivities
prevent magneto-rotational turbulence while allowing shear-generated
large-scale magnetic fields. The mass column in the undead zone is typically
greater than the column in the turbulent surface layers. The results support
the idea that the dead and undead zones are robust consequences of cold, dusty
gas with mass columns exceeding 1000 g/cm^2.
