Small-angle proton elastic scattering from the neutron-rich isotopes 6He and 8He, and from 4He, at 0.7 GeV in inverse kinematics Original Research Article

Absolute differential cross sections for elastic p 4He, p 6He and p 8He small-angle scattering were measured in inverse kinematics with secondary 4,6,8He-beams at an energy near 0.7 GeV/u. The experiment was performed using beams from the heavy-ion synchrotron SIS and the fragment separator FRS of GSI Darmstadt. The hydrogen-filled ionization chamber IKAR served simultaneously as a gas target and a detector for the recoil protons. Projectile scattering angles were measured with multi-wire tracking detectors. For proton scattering from the neutron-rich isotopes 6He and 8He, differential elastic-scattering cross sections View the MathML source were deduced in the range 0.002⩽|t|⩽0.05 (GeV/c)2 of the four-momentum transfer squared t. For elastic p 4He scattering, the data obtained in the t-range 0.002⩽|t|⩽0.02 (GeV/c)2 supplement the results from an earlier work performed in direct kinematics. From the differential cross sections the integral elastic-scattering cross sections View the MathML source, the total cross sections View the MathML source, and the total reaction cross sections View the MathML source for the proton–nucleus strong interaction were evaluated. The data obtained on View the MathML source allow the radial matter distributions in the 6He and 8He nuclei to be determined and the corresponding root-mean-square matter radii to be deduced.