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B How do beta particles remove electrons?

  1. Apr 12, 2016 #1
    Hello all,

    I'm just learning about beta decay and the emission of beta particles. I have come to an understanding that this is ionising radiation because it has the ability to remove electrons and turn the molecules it interacts with into ions. I've looked on the Internet for this information but have not found anything detailing how a beta particle actually 'removes electrons'.

    Currently, I am lead to believe that annihilation occurs from the release of an positron, but have not found any credible source to back up this statement.

    This is all new to me, so excuse my ignorance.
  2. jcsd
  3. Apr 13, 2016 #2


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    During beta minus decay, an electron is emitted, and during beta minus decay, a positron is emitted.
    The emitted electron/positron is usually energetic, because it carries some of the energy freed from the decay.
    When this electron hits an atom, it gives some of its kinetical energy to the atom, which causes an electron in that atoms shell to be ionized (that means, the electron is so excited, it leaves the atom shell and therefore be a free electron). This causes molecular bonds to be broken.
    Ionizing radiation is called ionizing, because it has enough energy to knock off electrons from atoms. This has nothing to do what kind of particle we are talking about, if a photon, an alpha particle, an electron have enough energy, they ionize stuff. The positrons have another different effect, because they are the corresponding antiparticles of electrons, if they are in contact with electrons, they annihilate (they turn their whole mass into energy in two or three photons).
    You can read the wiki about electron shells and orbitals. When you give energy to an electron in the atom shell, it moves to a higher shell. When you give enough energy, the electron has energy to move higher than the uppermost shell, so the electron gets outside the atom.
  4. Apr 13, 2016 #3


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    Even for positrons, the annihilation is a negligible part of the ionization effect: the electron or positron hits an electron and transfers energy to it, which ionizes the corresponding atom. The fast electron/positron loses some energy in the process, so the reactions stop after a while.
  5. Apr 13, 2016 #4
    They also need a way to transfer that energy to charged particles. Are neutrinos ionizing radiation?
  6. Apr 13, 2016 #5


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    As far as I know, neutrinos aren't considered to be ionizing radiation, because even at relative high energies, neutrinos rarely react with matter.
    Low energy neutrinos have such little cross sections, that they have a mean free path more than one light years in lead. Most of the neutrinos that come from sun just pass through the world without interacting with anything.
  7. Apr 13, 2016 #6


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    They do... for example electrons can scatter off electrons... scattering involves transfer of momentum and energy.
  8. Apr 13, 2016 #7


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    Do you understand something simpler than this? For example, do you understand how the ordinary fluorescent light bulb works? It appears that you haven't grasp the ability of electrons (not just beta particles) to interact and excite an atom when it collides with it. If this is true, then maybe you should start with something less "exotic", and look at something that is a lot more common than beta radiation and ionization, and look at the more common ionization occurring in the stuff already around you and more familiar.

  9. Apr 14, 2016 #8
    I admit, I am ignorant, but for my assignment I've decided to investigate this briefly amongst other concepts. I'm in Year 12 and have not done chemistry, this is the first time I've looked at atoms singularly since Year 10. Thanks for the suggestion though.
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