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Subatomic Physics

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8.8. References 237<br />

8.4. Verify the steps in footnote 1.<br />

8.5. Calculate the commutator (8.11).<br />

8.6. Justify that the isospin of the deuteron is zero<br />

(a) By using experimental information.<br />

(b) By considering the generalized Pauli principle stating that the total wave<br />

function, assumed to be a product of space, spin, and isospin parts, must<br />

be antisymmetric under the exchange of the two nucleons.<br />

8.7. The reaction<br />

dd −→ απ 0<br />

has been observed (see E.J. Stephenson et al., Phys. Rev. Lett. 91, 142302<br />

(2003)), but with a very small cross section. The isospin of the deuteron and<br />

the alpha particle are known to be zero. What does the abnormally small<br />

cross section of the reaction tell us?<br />

8.8. Verify Eq. (8.37), Eq. (8.38).<br />

8.9. ∗ Study the energy levels of the A =12isobars.<br />

(a) Sketch the energy level diagrams.<br />

(b) Justify that the ground state and the first few excited states of 12 Chave<br />

isospin zero.<br />

(c) Find the first I =1statein 12 C and justify that it forms an isospin<br />

triplet with the ground states of 12 Band 12 N.<br />

8.10. Consider the reactions<br />

d 16 O −→ α 14 N<br />

d 12 C −→ p 13 C.<br />

Assume isospin invariance. What are the values of I of the states in 14 N<br />

and 13 C that can be reached by these reactions? ( 16 O, 12 C, α, andd denote<br />

ground states; 14 Nand 13 C can be excited.)<br />

8.11. ∗ Consider the beta decay of 14 O to the first and second excited states in 14 N.<br />

Normally, a beta decay will have a lifetime that is approximately proportional<br />

to E −5 ,whereE is the maximum energy of the beta particles. Use isospin<br />

invariance to explain the observed branching ratio.

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