DISTINCTIONS BETWEEN THE CROSS-SECTIONS FOR HE-3 INTERACTION WITH NI-58 AND NI-64 NUCLEI

The total cross sections for the interaction of 95-MeV He-3 nuclei wit h Ni-58 and Ni-64 nuclei have been measured. The inclusive spectra of light charged particles formed in these interactions have been determi ned experimentally for scattering-angle values of 15 degrees, 20 degre es, 25 degrees, 30 degrees and 120 degrees. The spectra of protons and deuterons are found to develop maxima associated with 3He breakup, wh ile the spectra of deuterons and tritons display structures that can t entatively be attributed to neutron pickup by breakup fragments from a target nucleus. On average, the isotope distinctions between the meas ured reaction cross sections amount to 10-20%. The background pedestal s under the breakup maxima have been calculated with the aid of the AL ICE-92 code. The results of these calculations formed the basis for de termining the yields of protons and neutrons from 3He breakup. The int egrated breakup cross sections have been estimated at 380 +/- 100 mb f or Ni-58 and at 340 +/- 90 mb for Ni-64. The measured value of the tot al reaction cross section for a Ni-64 target is larger than the corres ponding value for Ni-58 by 175 +/- 70 mb. Within the shell model, this distinction can be explained by a more extended matter distribution i n Ni-64 than in Ni-58. That the yield of particles from He-3 breakup o n a Ni-58 is greater than the yield from the corresponding process on Ni-64 can also be due to distinctions between the matter distributions in these nuclei because, according to diffraction theory, the cross s ection is greater for processes occurring on more compact target nucle i.