The Instrumentation Center



Contributor: Alyson Lautar. Alyson is an undergraduate student of Pharmacy at UT and donated the smoke alarm.

About the Display: Americium 241 is used in smoke detectors because it detects a wide range of fire conditions. They are also less expensive and easier to install than their photoelectric counterparts. 
Americium releases alpha - particle, which can be measured at 0.9 micro-Curie. These alpha particles collide with oxygen and nitrogen in the air to create charged particles, or ions, in the detector's ionization chamber.
These ions are collected by a low level voltage that is applied across the chamber. When the ions are collected, a small steady electric current flows between two electrodes.
If smoke reaches the detector, particles from the smoke will attach to the ions formed from the alpha particles and oxygen or nitrogen. With fewer ions reaching their destination, the electric current drops, triggering the alarm.
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Symbol: Am

Atomic Number: 95

Atomic Mass: 243 u

Electron Configuration: [Rn] 5f77s2

Year Discovered: 1945

Discovered By: Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso

Last Updated: 6/27/22