If that were the goal, then it would make more sense to use a nuclear exit sign. The signs are illuminated by small capsules of tritium gas (a radioisotope of hydrogen manufactured in nuclear reactors) which are coated on the inside with a phosphor. The tritium decays by ejecting beta particles, which bang into the phosphor, causing it to glow. The signs have a service life of about ten years. (The half-life of the tritium that powers them is about twelve.)
Garrett A. Wollman | As the Constitution endures, persons in every snipped-for-privacy@csail.mit.edu | generation can invoke its principles in their own Opinions not those | search for greater freedom. of MIT or CSAIL. | - A. Kennedy, Lawrence v. Texas, 539 U.S. 558 (2003)
[TELECOM Digest Editor's Note: But was that type of exit sign (using tritium gas) generally avaialable in the middle 1970's, which is when I recall seeing the building janitor using his technique and discussing it? There are also exit signs illuminated with tiny little flourescent tubes are there not? I think those are sort of new, within the last 15-20 years. PAT]