-He4 inelastic cross sections have been measured at T=180 MeV. In the region of the J=1- states Ex 23 to 30 MeV) the +- cross-section ratio R was found to be 1.05 ± 0.08 at lab=30°. Such a small deviation from 1.0 implies that isospin mixing between the T=0 and T=1 states in He4 is quite weak, in striking contrast to the strong isospin mixing deduced from the large ratio of photonucleon cross sections, R=(,p)(,n)1.7. Thus the conclusion drawn from the photonucleon work, that there is a large charge-symmetry-breaking nuclear force in He4, needs to be reexamined.
ASJC Scopus subject areas
- Physics and Astronomy(all)