Absolute (γ, p0) and (γ, p1) cross sections and angular distributions for the closed-neutron shell nucleusY89

Absolute ($\gamma , p_0$) and ($\gamma , p_1$) differential cross sections for ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$ were measured at seven angles in the energy interval between 13 and 24.6 MeV, from which the angular distribution coefficients were deduced by fitting a sum of Legendre polynomials. In these cross sections we observe a number of isolated resonances which can be identified as the isobaric analogs of known $\frac{1}{2^{+}}$ and $\frac{3}{2^{+}}$ excited states in the ${}_{}{}^{89}{}_{}{}^{}\mathrm{Sr}$ parent nucleus. The appearance of a maximum around 21 MeV excitation energy in both total cross sections may indicate the existence of the $T_{>}$ coherent dipole state. From the angular distribution coefficients in the ($\gamma , p_0$) channel, an upper and lower limit for the $E2\mathrm{}$ photon absorption were estimated as being equal to 22% and 6%, respectively, of the total $E2\mathrm{}$ energy-weighted sum rule.