Collective Excitations in the Zirconium Isotopes

Angular distributions have been derived for the scattering of 43-MeV alpha particles by ${\mathrm{Zr}}^{90}$, ${\mathrm{Zr}}^{91}$, ${\mathrm{Zr}}^{92}$, and ${\mathrm{Zr}}^{94}$. Angular distributions for elastic scattering for the $l=2\mathrm{}$ transitions, for the $l=3\mathrm{}$ transitions, and for many other peaks are presented. The collective excitations in ${\mathrm{Zr}}^{92}$ and ${\mathrm{Zr}}^{94}$ are quite similar, and resemble those of the Ni and Zn isotopes. However, the $l=3\mathrm{}$ transition is more prominent than the $l=2\mathrm{}$ transition in all four zirconium isotopes.