Separation of [Delta][ital S]=0 and [Delta][ital S]=1 in the response of [sup 12]C to 318 MeV protons

Angular distributions of the double-differential cross section [ital d][sup 2][sigma]/[ital d][Omega] [ital dE] ([sigma]) and the spin-flip probability [ital S][sub [ital n][ital n]] have been measured for inclusive inelastic proton scattering from [sup 12]C at [ital E][sub [ital p]]=318 MeV. Data have been obtained over an excitation energy range 9 MeV [le][ital E][sub [ital x]][le]42 MeV for laboratory scattering angles of 3[degree], 5[degree], 7[degree], 9[degree], 12[degree], 15[degree], and 18[degree]. Multipole decompositions of angular distributions of both the spin-flip cross section [sigma][sub SF]=[sigma][ital S][sub [ital n][ital n]] and the estimated cross section for [Delta][ital S]=0 transitions have been performed. The distribution of deduced [Delta][ital L]=1, [Delta][ital S]=0 (the giant-dipole resonance) strength peaks near [ital E][sub [ital x]]=22 MeV; although there is apparently much more strength relative to the energy-weighted sum rule (EWSR) than expected, this appears to be an artifact of instrumental background at small angles. Approximately 55% of the EWSR for [Delta][ital L]=2, [Delta][ital S]=0 was observed spread uniformly across the spectrum with no evidence for a giant-quadrupole resonance. Angular distributions for [sigma][sub SF] were analyzed using the predictions from random-phase approximation calculations for the nuclear structure and distorted-wave impulse approximation calculations for the scattering. These predictions are found tomore » provide a good description of the [sigma][sub SF] data above [ital E][sub [ital x]]=25 MeV; values of [ital S][sub [ital n][ital n]] are predicted somewhat too low in this region.« less