Ok, if you're not already familiar with the 'hafnium reactor', read a little about it here..
Now, as for it's x-spectrum amplification property, does it actually work via an induced gamma decay? I'm pretty sure they use the metastable isomer hafnium-172 because it has a high atomic number. But it seems like all the requirements for gamma decay demand is that the nucleus be excited to the point to where it releases a photon. Are both the Nuetrons and Protons releasing a photon, or is it really a positron emission that will soon after annihilate into gamma rays (probably the latter)?
Even so, can somebody explain how the nucleus emits a photon and which partical is doing it?