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Protecting Unexposed Film from Cosmic Radiation?
iblink asks: "Last year Fujifilm stopped producing a color slide E-6 sheet film called Velvia 50. It has unique color characteristics that I love so I decided to purchase the remaining stocks in Europe. I now have hundreds of boxes that need to be stored for up to thirty years. A number of film experts assured me that freezing the Velvia would stabilize the dyes for long term use. However, they all mentioned that cosmic radiation would eventually fog the film, and they offered little help in finding a relatively inexpensive barrier. I found various ideas on proton cosmic radiation barriers — a big bucket of water, lead, certain plastics — but nothing convincing or sufficiently detailed (which plastic? How thick?). The film is currently in a freezer, unprotected. Any ideas?"
Were any of the film experts from FujiFilm? They may have some guidance for you. As them how they store film stocks.
--Mike
The change in sweetener is a more subtle thing than trying to pass off New Coke in the old Coke cans. No, I didn't notice the change. How long ago was it?
OTOH, ask those Dr. Pepper fans who live near and dote on the output of the one Dr. Pepper bottler in the U.S. who still uses cane sugar. They'll tell you they can easily tell the difference.
Nope. A nuclear bunker won't do it. You need one of these: http://www.sno.phy.queensu.ca/images/mine.GIF.
The box will give some protection, the metal of the freezer some, a lead box some, a 2km deep mine some... how much do you want? All radiation cannot be shielded because your shielding material will invariably be radioactive. Although, you can cut down that effect a bit by purchasing very expensive ancient lead from Roman shipwrecks. You'll be competing with a couple of observatories though.
It's counterintuitive, but shielding can actually make more radiation. The problem is that when a high energy cosmic ray strikes a nucleus, it can make a whole bunch of secondary particles which still have a lot of energy. Then those particles interact again, and so on, producing a "shower" of particles that can interact with your film. Sensitive neutrino experiments go far under the earth's surface to avoid cosmic rays, and even there they get a fair number of (low interacting) muons. I helped test a large space astronomy observatory and we regularly got blatted by cosmic ray showers, even though the observatory was inside a pressure vessel with thick steel walls. Proper shielding is an art.
Burying your film underground may make things worse too... if you live in an area rich in radioactive soil or radon gas. Building materials like concrete can often also be contaminated with uranium.
you joke but thats pretty much what you do when you want to minimise cosmic ray interference. To be honest your second best bet due to the natural radioactivity you mention is the stick it in a tunnel under a moutain .
Seriously its actually really surprising how many cosmic rays are hitting you right now. They are also extremely penetrating, often being muons (by the time they reach us). Basically its already got through 120km of atmosphere which although isnt that dense, it sure is thick so you're going to need a lot of shielding. And in 5 minutes at least one has hit you. Over 30 years that builds up. To really drive it home, it you are ever never CERN, stop in and see their microcosmin, look at the cosmic ray detector there and be amazed at how often it goes off.