ambient radiation???

Discussion in 'B&W: Film, Paper, Chemistry' started by djkloss, May 29, 2008.

  1. djkloss

    djkloss Subscriber

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    what is that? I tried goggling the term but couldn't find anything that I could understand in plain English. I read in a few different forums it can fog film.

    Thanks
     
  2. frdrx

    frdrx Member

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    Radiation present in the surrounding environment.
     
  3. PeterB

    PeterB Subscriber

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    Better known as Background Radiation.

    There are 3 sources. The earth, the upper atmosphere and outer space. the latter two are impractical to protect against. Such high energy photons (gamma radiation) and particles(cosmic rays) pass through any practical shielding you choose to place around your film. Over time the radiation will reduce the contrast of your film and paper.

    Kodak has is a bit more info here and here.

     
  4. Dan Henderson

    Dan Henderson Member

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    Over time the radiation will reduce the contrast of your film and paper.

    So I can blame ambient radiation for the reduction in contrast of my thinking as well? I knew I should have started wearing an aluminum foil hat years ago!
     
  5. djkloss

    djkloss Subscriber

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    Sounds good to me!
     
  6. panastasia

    panastasia Member

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    It wouldn't do any good, some particles, neutrinos, are believed to be able to travel through lead with a thickness measured in light years.
     
  7. milkplus-mesto

    milkplus-mesto Member

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    ambient radiation (according to the physics i've been taught) is usually 3-4 counts per second, on a standard geiger tube/counter.
     
  8. Photo Engineer

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    Ummm, for this you would need a lead helmet.

    PE
     
  9. Vaughn

    Vaughn Subscriber

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    And a footballer's neck muscles!

    Vaughn
     
  10. rwyoung

    rwyoung Member

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    They will in fact collide on rare occasions. The Icecube Observatory at the South Pole is looking for the Cherenkov (spelling?) radiation produced when a neutrino strikes a water molecule.

    http://icecube.wisc.edu/
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    Neutrinos will pass through film and our bodies with little to no harm. Its the bigger klunkers with more energy that do the damage.

    PE
     
  12. Ole

    Ole Moderator Staff Member Moderator

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    Cosmic radiation increases with altitude. So it's really mostly a problem if you live in La Paz, Bolivia; or if you tend to carry film with you on intercontinental flights.

    Terrestrial background radiation varies with location, and there are places where I would not like to live. There's also a very small component from radioactive Potassium in our bodies and in the film itself!

    So since there's very little you can do about "ambient radiation" (except if you live on uranium-rich ground), it's best not to worry about it. :smile:
     
  13. Photo Engineer

    Photo Engineer Subscriber

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    I would be more concerned about radon in the basement. Film has survived one week on the moon with no bad effects. It has survived days in orbit as well.

    PE
     
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  15. Ole

    Ole Moderator Staff Member Moderator

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    Precisely. And that's the only time you can really do anything about ambient radiation: If you live on uranium-rich ground, have your basement checked for Radon buildup. Alpha particles from radon won't penetrate your skin, but if you inhale the gas the alpha particles will be released inside your body where they can do maximum harm.

    I used to work with radioactive sources whose activity was measured in Gigabequerel. Even that can be done safely (and without fogging film) if you know what you are doing and the correct procedures are followed.
     
  16. djkloss

    djkloss Subscriber

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    Well thank you all for your 'over & above' responses. I always know I can count on Apuggers for answers to my questions. When I put my old Cooke-Telar barrel lens in the same camera bag with my loaded film holders, and then read the words 'ambient' & 'radiation', and foma film has higher density, I didn't know what to think. I started reading all sorts of things.

    So thanks guys!
    Dorothy
     
  17. MartinP

    MartinP Member

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    As I recall, the higher energy particles go right through the earth . . a lead hat isn't going to help ;o)
     
  18. Frank Szabo

    Frank Szabo Member

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    A thin lead-foil hat would offer more protection.

    FYI - I usually blame the wife's gray cat.

    Frank
     
  19. Photo Engineer

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    Most high energy particles are slow klunkers that are either stopped or broken up by the atmosphere. They do not penetrate the earth to any great depth and do the most damage to film. They are stopped by enough lead.

    Neutrinos are fast particles that pass through the earth. They are believed to be weightless (or massless) and travel at the speed of light.

    PE
     
  20. keithwms

    keithwms Member

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    Ionizing radiation is the principal concern, since the development process is of course based on redox. Neutrals (like the neutrinos) have very low cross sections in general, although of course neutrons do have a high cross section for interaction with protons and can also decay down.

    What really annoys me are the neutral kaons. I am quite certain that somebody is directing a beam of them at my brain lately, causing me to think strange thoughts.
     
  21. waynecrider

    waynecrider Member

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    From what I understand, the magnetic poles which shields us to whatever degree from radiation, including solar radiation, is undergoing a shift. This is the changing of the magnetic poles. As the magnetic pole fields change (actually move) they weaken and allow more radiation to hit the earth. This from what I understand will increase skin cancers and have other effects on such things are crops. Of course this will take quite a long time before it is completed, but in the meantime it effects are starting to manifest. Apparently the changing of the poles is in combination with the rotation of the earth changing and the expected slight tilt. There is a documentary that was made on the subject and aired on the public broadcasting stations last year. If you want to read up on the subject do a search on "earth changing poles" of the like.
     
  22. Ole

    Ole Moderator Staff Member Moderator

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    Wayne, please do the search yourself before spreading pseudoscience.

    Except for the fact that the magnetic field is weakening very slowly which may or may not presage a flip, everything you have referred to is balderdash to put it nicely.
     
  23. Photo Engineer

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    Acutally, the magnetic field of the earth is weakening, and also it 'bends' the solar wind around the earth while creating a band of particles circling the earth. This band is the Van Allen belt. So, in a sense, the magnetic field does shield the Earth. At the same time, the UV is blocked by the Ozone layer which is decaying and the UV is the major contributor to skin cancers. Cosmic radiation is weakly blocked by the magnetic field and also by the atmosphere.

    It is believed that the magnetic poles have shifted every several hundred thousand years, and this has been extensively discussed in science journals but due to the lack of positive evidence it is a theory at this point with reasonably good backing.

    The earth and any planet with a metallic core or a molten magnetic core has a magentic field with a strong influence on solar wind. Thus, Earth and Jupiter have strong fields due to iron and metallic hydrogen respectively. Mars has virtually no field and is weakly shielded from solar (and cosmic) radiation. The solar wind is considered to be a contributor to the conditions on both Mars and Venus.

    The sun has a huge magnetic field itself, and in addition there is a 'sphere' around the entire solar system which limits the extent of the size of the solar wind. The reflection of the solar wind from this sphere was recently detected as a signal by an astronomy team working with the Pioneer sattelites. They have named the field and its reflection or limiting ability in a recent article. It is approximately 10 - 20 Billion miles in radius.

    There is a distinction between cosmic rays and solar wind, although both are made up of ionizing radiation to some extent. Cosmic rays are directed at us from all directions at about the same intensity, whereas the solar wind is unidirectional and shaped like a teardrop as it strikes the earth's magnetic field and is deflected.

    You guys should read "Science News" and watch "The Universe" and "The Planets" on the Science Channel and Discovery.

    PE
     
  24. Monophoto

    Monophoto Member

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    Back in the dark ages when I was in high school, I attempted a science project to detect background radiation, or more specifically, radioactive fallout from nuclear testing (this was in the early 60s) using photographic film. A friend helped me select a high-speed black and white film (Ansco Super Hypan) that I cut into small pieces, wrapped in black plastic and then left outdoors for several days before processing. The hypothesis in this "research" was that fallout particles would result in pinpoint exposure of the film that would show up after processing. That was my first experience with processing film (in the bathroom using a monobath), and while it probably helped form my current interest in photography, was a failure as a science project.

    Incidentally, I heard a presentation a few months ago by a physician who has some association with NASA who pointed out that astronauts are carefully monitored for exposure to background radiation. The duration of time in space has traditionally been limited to minimize exposure. It is known that radiation exposure can, over time, lead to various forms of cancer. So far, one astronaut has died of leukemia, but it isn't known if that was an anomaly or a consequence of exposure during space flight, and the other members of the astronaut fleet are monitored very carefully for any signs of problem.

    She also noted that one of the concerns in any future longer duration space flights (eg, Mars) is that the astronauts will be exposed to much more radiation than on orbiter or moon flights, and that as a result, it is likely that the individuals who are finally selected for these journeys will be much older than traditional astronauts partly to minimize the risk that they could eventually develop cancer as a consequence of that exposure.
     
  25. Photo Engineer

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    After the first nuclear tests in the US, Kodak observed an increase in fog in many products. Tests found that it was due to fallout being brought in on shoes. At that point, Kodak installed shoe washers at all entry points into Kodak Park buildings in which emulsions were made or in which coatings were made. The only exceptions, AFAIK, were the research labs buildings (at that time, B-3 and B-59) and the new research buildings also lacked these devices.

    PE
     
  26. panastasia

    panastasia Member

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    Kaons are strange virtual particles, AFAIK, so you could be right about that. I'm not sure about a beam though, they don't travel a great distance and exist for some small fraction of a millisecond during decay interactions. But then there are those quantum uncertainties - 'spooky action from a distance'.