Is it an Americium element sensor for a fire/smoke alarm or a similar detector?
If so, Americium is a man-made radioactive element created in nuclear reactors from plutonium. It's most important isotope is Americium-241 and is popularly used in the ionization chamber of most smoke detectors. It does emit both alpha particles and low level gamma radiation. Americium is abundant on site, after nuclear weapons detonations. Americium-241 is a long-lived radionuclide and has a half-life of 432 years!!!
Now the bigger question is whether you have handled that device to photograph it for this thread? It's not an element to be fiddling around with, even though it looks harmless. If you did handle it outside the ionization chamber without using protective measures, the dosage of gamma rays you received is low and likely to be harmless depending upon your body's physical make-up. A professional radiation meter would yield a reading as to it's potential for health risks. Here's a snippet I found on Am-241:
Exposure to Americium:
Smoke detectors containing Am-241 also provide some radiation exposure. However, the radiation exposure people receive from a smoke detector is very low. The health risk reduction from the fire protection vastly outweighs the health risk from the radiation. That said, you should still handle smoke detectors containing americium with care. To avoid exposure:
- never dismantle a smoke detector
- never burn a smoke detector in your fireplace
- check with your local fire department for safe disposal procedures
What does americium-241 do once it gets into the body?
Once in the body, americium-241 tends to concentrate in the bone, liver, and muscle. It can stay in the body for decades and continue to expose the surrounding tissues to radiation, and increase your risk of developing cancer.
When inhaled, some Am-241 remains in the lungs, depending upon the particle size and the chemical form of the americium compound. The chemical forms that dissolve easily may pass into the bloodstream from the lungs. The chemical forms that dissolve less easily tend to remain in the lungs, or are coughed up through the lung's natural defense system, and swallowed. From the stomach swallowed americium may dissolve and pass into the bloodstream. However, undissolved material passes from the body through the feces.