This looks like it measures smoke density by measuring radiation. The americium is bound up in a gold matrix called "Americium alpha foil" and the sensor essent

This looks like it measures smoke density by measuring radiation. The americium is bound up in a gold matrix called "Americium alpha foil" and the sensor essentially measures how many alpha particles make it through the smoke or how much the gamma emissions ionize it? I can't tell. According to some random Nuclear Regulatory Commission documents, a specific EC 23095-1 with Serial no. 830101 was used as the calibration standard for testing other MICs: https://www.nrc.gov/docs/ML0037/ML003770968.pdf https://www.nrc.gov/docs/ML0037/ML003770968.pdf