Talk:Spinthariscope

Media Reference to article
http://cosmiclog.msnbc.msn.com/archive/2006/12/15/21117.aspx FancyPants 22:27, 17 December 2006 (UTC)

Radiation?
Is there any danger from any of these devices? Bizzybody (talk) 10:01, 12 October 2010 (UTC)

Good question. I'll try to answer it.

I've measured two modern spinthariscopes (made by United Nuclear, the primary producer today) with a Geiger counter. I had to use a very sensitive one to observe any radiation beyond normal background radiation. Background radiation is about 20 times greater than the radiation from one of these.

Thus, the danger from one of these devices is if it is dropped and the glass lens is shattered. Then there would be glass shards to clean up.

The radiation source in a spinthariscope must be an alpha emitter. Alpha particles can not penetrate the walls or the glass viewer of the spinthariscope. An energetic beta particle might, as would gamma rays. But, since neither beta nor gamma make the spinthariscope "work", there's no point to using a radionuclide that emits these.

As the article notes, modern spinthariscopes use thorium which is minimally radioactive with a half-life of over 14 billion years. A few modern spinthariscopes were made using americium sources from a smoke detector, but the NRC put a stop to that (for licensing, not safety, reasons; the americium ones were safe but in technical violation of the license). Thorium is now used exclusively, which is OK with the NRC.

Antique spinthariscopes used radium or polonium as their source. Few, if any, of these still function. Polonium has a half life of 138 days; by now there are hardly any polonium atoms left in those spinthariscopes. The danger is with the radium based ones; they are still just as radioactive, but the zinc sulfide screen has burnt out. Any radium-based product must be treated with care; radium is particularly dangerous since in addition to its high radioactivity the body treats it as calcium.

I would not hesitate to look through an antique radium-based spinthariscope once to see if it still works. But I would not do so routinely, and I certainly would not give one to a child.

I would not have any such problem with a modern spinthariscope. It makes a fine gift for an older science-minded child who can understand (and obey) "Don't take it apart. If you do, there's nothing to see, and the screen inside is delicate enough that it will probably break and ruin this expensive toy." Put another way, probably not good for a 1st grader, but OK for a middle schooler or older. —Preceding unsigned comment added by 206.124.149.116 (talk) 20:01, 13 November 2010 (UTC)