Levels in Y 89 Excited by the Y 89 (n,n'γ) Reaction

摘要: Gamma-ray spectra from the ${\mathrm{Y}}^{89}(n,{n}^{\ensuremath{'}}\ensuremath{\gamma})$ reaction have been studied using a ring geometry for fifteen ${\mathrm{Li}}^{7}(p,n)$ neutron energies ranging 0.78 to 3.36 MeV. Ground-state gamma-ray transitions arising levels in ${\mathrm{Y}}^{89}$ at 0.908\ifmmode\pm\else\textpm\fi{}0.003, 1.506\ifmmode\pm\else\textpm\fi{}0.005, 1.745\ifmmode\pm\else\textpm\fi{}0.006, 2.84\ifmmode\pm\else\textpm\fi{}0.02, and 3.05\ifmmode\pm\else\textpm\fi{}0.03 MeV, as well cascade gamma rays of 0.71\ifmmode\pm\else\textpm\fi{}0.01, 1.31\ifmmode\pm\else\textpm\fi{}0.01, 1.62\ifmmode\pm\else\textpm\fi{}0.01 MeV 2.22\ifmmode\pm\else\textpm\fi{}0.01 2.53\ifmmode\pm\else\textpm\fi{}0.01 observed. Spin parity assignments ${3/2}^{\ensuremath{-}}$ ${5/2}^{\ensuremath{-}}$ made 1.51- 1.75-MeV levels, primarily result comparisons ratios experimental cross sections these two with theory. Tentative are higher levels. Theoretical level excitation cross-section calculations various values spin done computer Hauser-Feshbach method optical-model transmission coefficients obtained theories. The angular distribution was calculated Satchler's theory corresponding section corrected accordingly.A new scheme is presented which takes into account all known data up present time. It suggested that some excited work may be due part least coupling ${p}_{\frac{1}{2}}$ proton ${2}^{+}$, ${3}^{\ensuremath{-}}$, (${2}^{+}$) ${\mathrm{Sr}}^{88}$ core.