Analog-State Resonances in theY89(p,n)Zr89andSr88(p,n)Y88Reactions

Abstract

Several compound-nucleus analog states formed in the reactions ${\mathrm{Y}}^{89}\mathrm{}(p,n)\mathrm{}{\mathrm{Zr}}^{89}$ and ${\mathrm{Sr}}^{88}\mathrm{}(p,n)\mathrm{}{\mathrm{Y}}^{88}$ were studied using a ${\mathrm{He}}^3$-filled proportional counter as a neutron spectrometer. 0° excitation curves and angular distributions were measured for both reactions. One striking feature of this data is the complete absence of the 5.02-MeV ($3^{-}$) resonance from the excitation curve for neutrons to the first excited state of ${\mathrm{Zr}}^{89}$. Most of the off-resonance data agree well with Hauser-Feshbach calculations, although there is some evidence for interference effects in the angular distributions measured near the 4.82-MeV resonance in the ${\mathrm{Y}}^{89}\mathrm{}(p,n)\mathrm{}{\mathrm{Zr}}^{89}$ reaction. Energy levels in ${\mathrm{Zr}}^{89}$ were determined to be 0, 590, 1105, 1470, 1645, and 1880 keV.