Alpha and Beta Particles

With the worldwide angst about Japan’s nuclear situation, it’s probably a good time to review alpha and beta particles. The particles were classified by Nobel Prize winner Ernest Rutherford, “the father of nuclear physics,” and together with gamma radiation (which is pure electromagnetic energy and not a particle form) comprised the first classically understood products resulting from radioactive decay.

  • A alpha particle contains two protons and two neutrons, the nucleus of a helium atom. It carries a positive charge of two units. Alpha particles are useful in smoke detectors and thermoelectric power generators like the ones they used to use for pacemakers.
  • A beta particle is a naked negatively-charged electron (or its positively-charged twin, the positron). In comparison to the alpha particle’s atomic mass of 4 units, an electron has one eight-thousandth the mass – 0.01%, or almost nothing at all.
  • As suggested by the cartoon at right, beta particles have greater penetrative capability; an alpha particle can be stopped by a sheet of paper while beta particles require metal shielding.


Does anybody else notice a parallel here? Alpha particles are positive, massive, doubly attractive and can make you talk funny if you inhale their essence. Beta particles are negative, don’t take up a lot of space and are difficult to get rid of. The beta particle also only has one ball. Do I really have to spell it out for you?


Was Ernest Rutherford ostensibly a hard scientist but really a crypto-anthropologist? Should Rutherford take place next to Richard Feynman as a scientist clued in to the true nature of the sexes? I don’t know and I have other research to do – but it is funny, no?

In all seriousness, it’s worth tooting Rutherford’s horn – he was a giant of his day, initiating a revolution in the atomic model so valid we still teach it to middle and high school students, observing the half-life characteristic of radioactive decay, theorizing on the existence of neutrons (later proven), splitting the atom for the first time  and becoming the first person to synthetically transmute one element from another (before him only nature’s radioactive processes could do that).


Filed under beta guide, science+technology

3 responses to “Alpha and Beta Particles

  1. Einstein: “God does not play dice with the universe.”
    Niels Bohr: “Bring the movies.”

    LOL. Great analogy.

    Funnily enough, Richard Feynmann talked about the wisdom of not buying drinks for bar girls in “Surely You’re Joking Mr Feynmann”.

  2. NMH

    Dont forget about gamma radiation, which is also released in certain nuclear decays.

    Radiaoactivity exposure (I would guess, not an expert at this) depends on two major things 1.) how far the radioactive material (Uranium-235, Plutonium-whatever) is blown out and how much is blown out, and 2.) The energies in the specific decay products. Not all beta and gamma emissions have the same energy: some released beta particles have lower energies and are relatively harmless, while some are very energetic particles which can pass through tissue and cause mutations with DNA. Same deal with gamma release from decaying atoms.

    I actually see the analogy most between alpha particles (which are harmless) and omega men–both have little potency

  3. Joe, don’t sell Einstein short. He was probably a master of aloof game; it is said he didn’t wear socks because he found them not worth the time it took to put them on.

    NMH, radioactive exposure is dependent on a) the rate of decay of an element, b) the energy released in each decay event, c) the total amount of material in the sample. Some nuclear decay products are very short in lifespan, so they can be safely stored briefly. In fact the radioactive steam in the Japanese reactors falls into this category; it can be safely vented into the atmosphere after a rest period to allow for decay. Uranium and plutonium have VERY long half lives (on the order of a billion years for uranium and thousands of years for plutonium) and release huge amounts of energy so they are existential threats to life if pollution occurs.

    Alpha particles aren’t harmless. They have low penetration depth but are highly ionizing; anything they hit in their travels is likely to be quite disturbed.

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