Rej. Florizone et al., SIMULTANEOUS MEASUREMENT OF THE (GAMMA,P) (GAMMA-N) CROSS-SECTION RATIO IN HE-4 AS A TEST OF CHARGE-SYMMETRY, Physical review letters, 72(22), 1994, pp. 3476-3479
We have measured (gamma,p) and (gamma,n) differential yields at 90-deg
rees for the two-body photodisintegration of He-4 using tagged photons
of energy E(gamma) = 25-60 MeV. Data for both channels were obtained
simultaneously using windowless DELTAE-E telescopes to detect the He-3
and H-3 recoils. The ratio of our angle-integrated yields, which is i
nsensitive to systematic uncertainties due to the simultaneity of the
measurements, agrees with calculations employing only charge-symmetric
nuclear interactions. Thus, within the present errors, our data show
no evidence of a significant charge-symmetry violation in He-4 in this
energy range.