Speaker
Description
The isospin character of the p-n pair and n-n pair at medium relative momentum has been observed in comparison with A=6 nuclei, 6Li, and 6He. We have measured the 6Li(p,dp) and 6He(p,dn) cross sections for the neutron pick-up domain with 70A MeV incident heavy ion on the solid hydrogen target[1] via inverse kinematics at RIPS facility in RIKEN. All the reaction products at forward angles, including recoiled nucleons N [p or n], were measured by plastic scintillator telescopes and identified unambiguously. The momentum transfer covers up to 1.0 fm-1 through a wide angular coverage, thus picking up the high-momentum neutrons correlated with protons in nuclei. In the (p,dp) reaction, we observed a strong population of deuteron-like states d+4He in 6Li but a weak population of neutron pairs ’n-n’+4He in 6He.
The data were compared with plane-wave and distorted-wave impulse approximation (DWIA) calculations with realistic elastic d(p,p)d and charge exchange reaction ’n-n’(p,n)d cross sections with the common procedure, which was successfully applied to the 16O(p,dp)[2]. The calculations with assumed spectroscopic amplitudes from theoretical estimation based on a three-body model[3] fairly reproduce the observed ratio of cross sections between 6Li and 6He. It indicates that the present DWIA framework works well at medium relative momenta. The observed strong isospin dependence in the NN pair indicates the presence of NN correlation in A=6 nuclei. In this talk, we will present new results of the experiment with 6Li(p,dp)4He and 6He(p,dn)4He and discuss the applied detailed reaction analysis.
[1] Y. Matsuda et al. Nuclear Instruments and Methods A643 (2011) 6-10
[2] S. Terashima et al. Phys. Rev. Lett. 121(2018) 242501
[3] W. Horiuchi and Y. Suzuki. Phys. Rev. C76(2007)024311
