Americum 241

Am-241 has a half-life of approximately 430 years and it a predominant alpha emitter with some beta emissions as well. In addition to the particulate decay, it also is a moderate gamma ray emitter. Here are the decay energies reported for Am-241:

Alpha: 5.5 MeV. (Though it is stopped by a thin piece of paper).

Beta: 0.052 MeV. (Doesn't take much to stop this).

Gamma: 0.033 MeV. (About 0.03 MeV is the borderline for "don't worry about it" levels. Above 0.03 MeV is when you should start to take notice of what is around you. For comparison's sake, the gamma emmissions of U-238 is only about 0.0014 MeV. It's U-235 that has the quite strong gamma emissions of 0.16 MeV. This is why natural uranium, and uranium ores, are far more dangerous than depleted uranium. DU doesn't have nearly the amount of strong gamma emissions that the other type of uranium have).