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Please, help me understand radioactivity.

  1. Dec 5, 2008 #1
    1. when alpha particles are emitted, the atomic number decreases by2, but is the new element charged due to more number of electrons? If not, what happens at the nuclear level? Please, Explain it simillarly about beta particles.
    2.when describing the emission of beta particles, we say that

    1n0 -----------> 1p+1 + 0e-1

    but at the time of describing the nuclear stability, we say that

    1n0 -----------> 1p+1 + 0π-1

    SO are the pion and the electron one and the same? or does the neutron undergoes different reactions at different times? If yes, how does the neutron come to know, which reaction to undergo and when? If not, then what does exactly happen?

    3. At the time of gamma radiations, neither atomic nor mass no. of an atom change, so what is the benefit or cause for any radioactive atom to emit gamma radiations? Does the radiation causes it to stabilize itself by some other way?

    Please answer all these questions and you will help me understand all the concepts clearly.
  2. jcsd
  3. Dec 5, 2008 #2


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    1. The alpha particle HAS Z=2!! So it is carrying away two protons. So if it was a neutral atom decaying with alpha it will become a 2- ion

    Beta decay, a neutron (Z=0) becomes proton (Z=+1) and electron (Z=-1).

    2. No the pion and electron are different particles, and the guy who told you that neutrons can decay to a proton and a pion is wrong. Where did you find it? Maybe you are refering to the good'ol pion exchange model of the strong interaction?

    3. Compare to atoms exmitting characteristic X-rays by letting the electron changing its state to a lower lyging one in Energy space -> protons and neutrons are orbiting around each other and can be excited to different levels and so on, so when going back to the ground state, Gamma rays are emitted.
  4. Dec 7, 2008 #3
    In fact my concepts about the model are quite unclear. So will you please tell me what the new model of strong interaction is and what the old model failed to explain to give rise to the new one?
  5. Dec 7, 2008 #4


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    I am not telling you that it is wrong because it is old, I am telling you that the neutron don't DECAY in this process:

    1n0 -----------> 1p+1 + 0π-1

    You are mixing concepts, you are mixing decay and a VIRTUAL process.

    Any way, your question is in GENERAL this one:

    Suppose you have a particle A, which has several decay modes: B,C,D

    Now when the particle A "decides" to decay, it will choose one of possible B,C,D. BUT each decay mode is not equal probable in general. Say that the probability of decaying into B is 20%, C 70% and D 10%. Then you are back to basic theory of probability...
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