||<p>Nearly mono-energetic, high intensity (~10<super>7</super> gamma/s), and approximately
100% linearly polarized gamma-ray beams at energies between 5.15 and 7.60 MeV were
used to induce photofission of <super>232</super>Th, <super>233,235,238</super>U,
<super>237</super>Np, and <super>239,240</super>Pu. Prompt fission neutron yields
parallel and perpendicular to the plane of beam polarization were measured using arrays
of 12-18 liquid scintillator detectors. Prompt neutron polarization asymmetries close
to zero were found for the even-odd actinides (<super>233,235</super>U, <super>237</super>Np,
and <super>239</super>Pu), while significant asymmetries were found for the even-even
actinides (<super>232</super>Th, <super>238</super>U, and <super>240</super>Pu).
Predictions based on previously measured fission fragment angular distributions combined
with a model of prompt neutron emission agree well with our experimental results.
Finally, we describe a new method of measuring the enrichment of special nuclear material
based on our results.</p>