• Nautalax@lemmy.world
    0·
    17 days ago

    So long as you don’t wind up with a piece of the alpha-emitter inside you (ex. by eating it, breathing it, introduction via a wound) they are radiologically harmless. Alpha particles are highly charged and comparatively heavy since they have two protons and two neutrons. That mass and charge means that they make a lot of collisions and dump a ton of energy along a short track… VERY short, like the diameter of an individual cell even. Devastating if they are doing that in living tissue due to massive energy deposition all concentrated in a particular area, but on the outside the layers of your skin will adequately protect you. Or, as memes of old have put it:

    They are of more concern as like an airborne gas or dusty contamination since you may not be aware if you are breathing them in or accidentally eating traces after touching a innocuous looking dusty surface and not washing your hands before lunch.

    A little thought exercise they tell you when you study radiation: if you were to hypothetically have four equivalent activity sources that emitted alpha, beta, gamma and neutron radiation, and you have only four methods of either putting one in your pocket, throwing it in the trash, eating it, or holding it in your hand, which emitter do you match to which method?

    Alpha is fine to hold in your hand since your skin will block the alpha particles; you want to avoid eating it because that would really mess you up. Beta has a bit more penetration so you don’t want to have it in your hand but the pocket is relatively fine. Neutron radiation is very penetrating except for moderators similar in mass to neutrons like the hydrogen atoms in water which the neutrons collide with and dump a ton of energy on; unfortunately you are made up of a lot of excellent moderating material where those neutrons would dump a lot of energy in you so you don’t want those anywhere near you and it’s best to throw that source away. Gammas are also highly penetrating so they don’t care that much about small differences like being in your hand or pocket but through having basically no mass and no charge they aren’t particularly likely to interact with you either so all else being equal they’re the safest of the emitters to have inside you if that’s a forced option.

      • Nautalax@lemmy.world
        0·
        17 days ago

        The idea is that it gets mostly blocked by the combo of the layers of clothes and skin so that kind of optimizes you not absorbing dose for that contrived scenario. If you swap beta with alpha then the beta will be doing more damage because it can penetrate the skin while the alpha is still entirely blocked. If you swap the beta with the gamma then the beta will be depositing basically all of the energy inside you and the gamma will not really be shielded at all from being in the pocket so that’s also more dose. If you have the neutron source swapped with the beta then although the beta is no longer a problem the neutrons will be penetrating you and moderating throughout your body which is bad. So beta in the pocket is the optimized option for that scenario even if it’s not necessarily where you would want to keep it in real life… similarly don’t actually go around eating gamma sources lol.

    • TallonMetroid@lemmy.worldEnglish
      0·
      17 days ago

      Wait, I thought neutrinos were the ones that were electromagnetically neutral and thus didn’t interact with anything (that’s why they’re so penetrative, they just ignore the electron shells).

      • Nautalax@lemmy.world
        0·
        17 days ago

        Neutrinos are indeed tremendously penetrating precisely due to very little mass and no charge, many are constantly streaming through the entire world and you at any given moment. They are also way less likely to interact with matter than gamma rays. Since they very rarely do much of anything (you have to build ridiculous facilities to have a chance of detecting their uncommon interactions) they are not really considered as ionizing radiation.

        Neutrons have much more mass but are still electrically neutral. Most materials have much more mass than a neutron so they bounce off and barely lose any energy in their collisions, sort of like when you throw a ping pong ball at a wall, which keeps them as highly penetrating in many materials. They only appreciably slow down when they collide with atoms similar in mass to them like the hydrogens in water, think like how a billiard ball will hit another and dump almost all of its energy into the similarly sized ball. So materials like water and concrete are good shielding for neutrons but lead not so much.

      • TheTimeKnife@lemmy.world
        0·
        17 days ago

        They are both neutral, but wildly different particles. Neutrons are larger composite particles composed of quarks, they are one of the typical atomic building blocks you learned about in school. Neutrinos are massless elementary particles that barely interact with you and flow through the earth from solar and cosmic sources.

        • Err(()).unwrap()@lemmy.world
          0·
          17 days ago

          Erm, actually, neutrinos aren’t massless. The Super-Kamiokande experiment has observed neutrinos to oscillate between electron-muon-tau lepton family numbers (or flavors), which means that they experience time and necessarily travel slower than the speed of light, which implies that they have a nonzero rest mass. This discovery changed the Standard Model and resulted in a Nobel prize.

    • Err(()).unwrap()@lemmy.world
      0·
      17 days ago

      they aren’t particularly likely to interact with you either so all else being equal they’re the safest of the emitters to have inside you

      First time I’ve heard of this. Care to give a source?

      (edit) By the way, actinium-225, a strong alpha emitter, is being used as cancer medication. Capsules are implanted near inoperable tumors and function like radiation therapy.