Good Point, Charles.? Yes, I fully agree — gammas and X-rays are both photons, and once they are emitted from the atom both look and behave the same.? From the IAEA Isotope Browser app, Ge-68 has a maximum X-ray energy of 10.26 keV at 5.68%, and if you consider three other X-rays between 9.225 and 10.26 keV, the total X-ray emissions add up to 50.34%.? At these relatively low energies, these X-rays would be attenuated relatively quickly in the air, let alone by the thickness of the material enclosing the source, so would have limited detectability at a distance.? I found a reference from an accelerator lab that indicated that 10 keV x-rays are attenuated to ~0.57 (57%) of its initial intensity by 1-meter of air.? Thus, the attenuation through 5-meters of air would reduce the intensity to about 6% of the original intensity, and 10-meters of air would reduce the intensity to 0.36% of the original intensity.? Once you couple in the effects of the inverse square law for a point source, I think you'd be hard pressed to detect 10 keV x-ray photons from a Ge-68 poiont source much beyond 6 or 7 meters.

However, as I mentioned in the earlier email, Ge-68 decays to Ga-68 which has a 67.7 minute half-life, and would effectively be in equilibrium with the Ge-68.? The Ga-68 does emit some gammas, the most abundant of which is 1077.34 keV at 3.22%, and total gamma emissions above 578 keV add up to 3.58%.? Ga-68 decays by positron emission, so it will also produce 511 keV annihilation photons with a total yield of 178%, which would be the most likely photons detectable from a distance.?

Good topic of discussion.? Have a great day, Charles.? 73

Ken -- WB?OCV