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Energy level diagram help

  1. Jun 22, 2010 #1
    Can anyone help with interpretation of this energy level diagram for Lithium-6 I found on internet--it is from the Duke University department of Physics.


    I am not sure I understand the equation for the 13.3 MeV energy level predicted--what exactly does it mean to have a minus (-) alpha ? Does this mean the energy of the alpha (~28.2957 MeV) is to be subtracted from the other members ? Is this alpha a type of negative energy potential, perhaps from antimatter ?

    Thanks for any help.
  2. jcsd
  3. Jun 22, 2010 #2


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    Any of the particles with a minus sign are on the output side of the process which is leading to Li6.

    In the case you are asking about, the reaction is Li7 + He3 -> Li6 + He4 (alpha).
  4. Jun 22, 2010 #3
    Yes, OK, thank you. 60.28 MeV binding energy (on right side of reaction) - 46.962 MeV (on left) = 13.3 MeV (the value given).

    Not sure if you noticed, but, if you apply the Ikeda Threshold Rule to the binding energy (in MeV) for supposed clusters (Li7 + He3 - He4), and subtract the sum (= 18.666 MeV) from the binding energy of Li6 (= 31.995 MeV), the result also is 13.3 MeV. This is why I asked about the interpretation of the minus (-) sign used for the alpha (He4). In this interpretation, the decay threshold for Li6 at 13.3 MeV results from the interaction of the three "clusters", and one must be antimatter alpha. What do you make of this observation ?
  5. Jun 23, 2010 #4


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    I am not sure of the observation you are trying to make.

    However the alpha particle is a matter particle, not anti-matter. An anti-matter alpha would have a charge of -2, consisting of a pair of anti-protons and a pair of anti-neutrons. There aren't any around!
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