Experimental Study and Distorted-Wave Predictions for the (He3,α) Reaction on Fe Isotopes

Angular distributions of some alpha-particle groups from the (${\mathrm{He}}^3$, $\alpha$) reaction on ${\mathrm{Fe}}^{54}$, ${\mathrm{Fe}}^{56}$, ${\mathrm{Fe}}^{57}$, and ${\mathrm{Fe}}^{58}$ have been obtained experimentally. The ${\mathrm{He}}^3$ beam energy was about 14.3 MeV except that data were also obtained for the ${\mathrm{Fe}}^{57}$ target with a beam energy of 24.9 MeV. Angular distributions were also obtained for ${\mathrm{He}}^3$ and alpha particles elastically scattered from ${\mathrm{Fe}}^{56}$. For the (${\mathrm{He}}^3$, $\alpha$) reaction, groups corresponding to $l=3\mathrm{}$ neutron transfers were peaked strongly forward, while groups corresponding to $l=1\mathrm{}$ neutron transfers were not but showed much more diffraction structure. The cross sections for the strong $l=3\mathrm{}$ groups were very much larger than those for the strongest of the $l=1\mathrm{}$ groups. This ratio is in distinct contrast to the results of ($d, t$) and ($p, d$) experiments on the same isotopes. In addition, the ${\mathrm{Fe}}^{57}({\mathrm{He}}^3, \alpha )$ reaction to the ground and first-excited states of ${\mathrm{Fe}}^{56}$ proceeded with a cross section lower by more than an order of magnitude than that expected on the basis of data from the ($d, t$) and ($p, d$) reactions.