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  1. #41

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    "LOL, all those people who are worried about radiation of thorium show that they don't have the slightest clue how radiation works. "

    And I suppose your credentials are degrees in Physics, Nuclear Engineering or are we reading the comments of a degreed Health Physicist?
    Other than those three disciplines I would suggest that individuals refrain from Posting what they 'think' and only what they 'know' to be fact concerning isotopic emmiters, the physical effects and biological effects.
    I commented once but just don't have the time nor inclination to address all the mis-statements.-Dick

  2. #42
    polyglot's Avatar
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    "Ever been to Utah? Ra-di-a-tion. Yes, indeed. You hear the most outrageous lies about it. Half-baked goggle-box do-gooders telling everybody it's bad for you. Pernicious nonsense! Everybody could stand a hundred chest x-rays a year. They ought to have them, too. When they canceled the project it almost did me in. One day my mind was full to bursting. The next day - nothing. Swept away. But I'll show them!"

  3. #43
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    Quote Originally Posted by budrichard View Post
    "LOL, all those people who are worried about radiation of thorium show that they don't have the slightest clue how radiation works. "

    And I suppose your credentials are degrees in Physics, Nuclear Engineering or are we reading the comments of a degreed Health Physicist?
    Other than those three disciplines I would suggest that individuals refrain from Posting what they 'think' and only what they 'know' to be fact concerning isotopic emmiters, the physical effects and biological effects.
    I commented once but just don't have the time nor inclination to address all the mis-statements.-Dick
    At least I did some serious research instead of letting myself make scared by the media and others the don't know squat about it. Most people are like sheep, they just take in whatever they see from the media, I on the other hand do a lot of reading and even inform myself with people who actually work with radioactive products. And what exactly was wrong with my post to begin with?? did it contain any lies?? NO IT DIDN'T! Thorium breaks down in the Alpha and Beta spectrum, not the Gamma or X-rays. Radium does emit Gamma rays, so that's not wrong either. The amount in those lenses are small and they are encapsulated in the glass, so unless you break the glass there is nothing to worry about. Of course radioactive compounds are not toys but in the Post Chernobyl era people are way too scared because the media pictured some grotesque misconceptions about nuclear radiation.
    Sure, I could give you a boring explanation who I really am but I rather let the Origami do the talking.

  4. #44

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    Quote Originally Posted by budrichard View Post
    The check function is purely electronic and verifies if the meter responds to a current. Whether the GM tube is still functional and will generate a current is anyones guess without an actual radioactive source emmitting gamma rays which is what most of these GM counters were designed to detect.
    It's not a "check function" that I'm refering to, but rather a check source. The check source, is a small sealed radioactive substance stuck on the side of the detector. The nuclear physics professor I bought this from told me what the substance was, but now I forget.... actinium maybe.

  5. #45

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    "One day my mind was full to bursting. The next day - nothing. Swept away. But I'll show them!

    From one of my all time favorite movies!!!
    "If you look at a thing nine hundred and ninety-nine times, you are perfectly safe; if you look at it the thousandth time, you are in frightful danger of seeing it for the first time." G.K.Chesterton

  6. #46

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    Quote Originally Posted by One_DaveT View Post
    It's not a "check function" that I'm refering to, but rather a check source. The check source, is a small sealed radioactive substance stuck on the side of the detector. The nuclear physics professor I bought this from told me what the substance was, but now I forget.... actinium maybe.
    If a radioactive isotope. it has a half life i.e. after a certain amount of time only one half will be left to disintegrate and provide readiation to check your GM tube. Therefore you need to know the isotope and half life to determine if the source is still effective in checking your GM. In short, just having a GM counter without the proper documentation and/or training, you don't really know if your detecting anything.-Dick

    "At least I did some serious research instead of letting myself make scared by the media and others the don't know squat about it. Most people are like sheep, they just take in whatever they see from the media, I on the other hand do a lot of reading and even inform myself with people who actually work with radioactive products. And what exactly was wrong with my post to begin with?? did it contain any lies?? NO IT DIDN'T! Thorium breaks down in the Alpha and Beta spectrum, not the Gamma or X-rays. Radium does emit Gamma rays, so that's not wrong either. The amount in those lenses are small and they are encapsulated in the glass, so unless you break the glass there is nothing to worry about. Of course radioactive compounds are not toys but in the Post Chernobyl era people are way too scared because the media pictured some grotesque misconceptions about nuclear radiation. "

    I never said anything was wrong with your Post. I was merely trying to ascertain your credentials. Your statements actually lead me to believe you had none in this area. Now that may be good and that may be bad. It's up to you to make that determination but to make the statement "in the Post Chernobyl era people are way too scared because the media pictured some grotesque misconceptions about nuclear radiation" shows an incomplete understanding about the subject and the dangers. My last statement still stands:
    "Other than those three disciplines I would suggest that individuals refrain from Posting what they 'think' and only what they 'know' to be fact concerning isotopic emmiters, the physical effects and biological effects.
    I commented once but just don't have the time nor inclination to address all the mis-statements"
    -Dick

  7. #47

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    Quote Originally Posted by budrichard View Post
    If a radioactive isotope. it has a half life i.e. after a certain amount of time only one half will be left to disintegrate and provide readiation to check your GM tube. Therefore you need to know the isotope and half life to determine if the source is still effective in checking your GM. In short, just having a GM counter without the proper documentation and/or training, you don't really know if your detecting anything.-Dick
    -Dick
    Yes, this is all pretty common knowledge for anyone with a little interest. No, you do not need to know the isotope and half life for a check source. I think you have an inverted view of how to use a check source. If as you imply, a radioactive isotope with a very short half life was used as standard check source , and disentragated long before my test, the result would be that the check source test would not register. This opens up the possibility of a false-negative, i.e. a dead detector that's not actually dead. However, there is no room for a false-positive, as you are concerned, i.e. a working detector that is actually dead. What can not be done with an unknown check source, is to callibrate the actual reading.

    I'm not really clear on what's driving this bad detector discussion. As I mentioned earlier, regarding the 1960's quip, I don't believe it to be the case. My detector was last callibrated in 1996, and it's a model that can be bought on-line today. Do you have one of the lenses that I have listed and believe it to be radioactive?

  8. #48

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    "Do you have one of the lenses that I have listed and believe it to be radioactive?"

    Nope, but I do have Trinitite, sand fused by the first Atomic Bomb blast and graphite from Chicago Pile Number One(CP1), the first Reactor.
    I don't spend my time worrying about these or lenses as there is real stuff to worry about.-Dick

  9. #49
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    Thorium-232 has a half-life of 14.05 billion years, which---though it's about the age of the universe---is still apparently shorter than the half-life of this tedious thread.

    @FilmOnly, when you fixate on minuscule risks that have virtually no chance of harming you, while you daily engage (I presume) in other activites that pose orders-of-magnitude higher risks to you without giving them a thought (you DO drive a car, no?), then, sorry, yes, that IS irrational. behavior.

    Now, you are perfectly within your rights to engage in irrational behavior that doesn't harm others; but don't call it something it's not, and expect to go unchallenged.

    Here expireth my half-life. I'm out.
    Last edited by MikeSeb; 11-29-2009 at 06:01 PM. Click to view previous post history.
    Michael Sebastian
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  10. #50

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    Just FYI, If you were using a Geiger-Mueller tube it is not going to detect alpha. You need an instrument specifically designed for alpha detection to detect alpha particles. However, with your "Geiger Counter" you may be able to detect the accompanying gamma or any beta radiation, if the detector has a beta window, that maybe emitted by radioactive daughters in the the decay chain.


    Quote Originally Posted by One_DaveT View Post
    Tonight I just learned about the use of thorium in lenses up until 1980's. This prompted me to go dig out my 60's vintage civilian defense geiger counter, which I bought years ago after some goof ball medical technician made a wise crack about the half life of the liter of barium I had just quaffed for a cat scan. (fwiw, the drinkable stuff is from a non-radioactive isotope).

    Anway, I put my old lenses to the test. I can say after scanning for alpha and beta particle that I believe the following lenses are Thorium-free:

    Nikkor-N 24/2.8 pre-AI
    Nikor-S.C 50/1.4 pre-AI
    Nikkor-P 105/2.5 pre-AI
    Nikkor-Q C 200/4 pre-AI

    FWIW, I checked a few other lenses:
    Zuiko OM 50/1.4
    Minolta Rokkor 200/3.5
    Minolta Rokkor 50/1.7

    After reading that Thorium in lenses goes back to 1937, I checked my Exakta lenses: Steinheil 135/3.5, Westenar 50/2.5..... nope.

    In hindsite, after reading wikipedia, it doesn't seem like much of an issue anyway. It says alpha particles from thorium can't even penetrate human skin, so even if I did have a thorium lens, it likely wouldn't be a concern unless I breathed the pulverized dust of a broken lens. Given that the use of it in commercial lenses stopped around 1980 makes me wonder if three-mile island incident in 1979, might have made marketing thorium lenses impossible, and lead to the end of it's use.

    Interesting diversion for the evening though.

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