Radioactive source, ALPHA, Polonium 210, low energy, suitable for classroom use, for study in radioactivity and absorbers. Some years ago, Americium 235 was the normal Alpha source used in the classroom. This product is now banned from being used as an Alpha source, however, it is used in millions of domestic smoke detectors.
The replacement is POLONIUM 210 which has a very short half-life of 135 days.
NOTE: About 18 months after purchase, the item is useless for experiments. Therefore we normally do not carry stocks of this item.