Probing the high-momentum component in the nucleon momentum distribution by nucleon emission from intermediate-energy nucleus-nucleus collisions

The free nucleon emission from intermediate-energy nucleus-nucleus collisions is proposed as a possible probe to study the high-momentum tail (HMT) in nucleon momentum distribution of nuclei. Within the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, the effect of HMT on free nucleon emission from the reactions of a light system ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ and heavy one ${}^{124}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ at the beam energies of 50 and 140 MeV/nucleon was investigated. We show that the probability of free nucleon emission, especially high-energy nucleons, is sensitive to the high-momentum component in nucleon momentum distribution of nuclei. The momentum distribution with HMT can lead to an increase of both high-energy free proton and neutron emission as compared to the free Fermi gas case for both symmetric and asymmetric nuclear systems.

Figure 1

The proton (neutron) momentum distribution in ${}^{12}\mathrm{C}$ obtained by the local density approximation (11). The black solid line and red dashed line denote the FFG and HMT cases, respectively. The dotted line is the momentum distribution taken from Ref. [29] and the dash-dotted line is the momentum distribution taken from the VMC calculation [57].

Figure 2

The proton and neutron momentum distributions in ${}^{124}\mathrm{Sn}$ calculated from the local density approximation.

Figure 3

Effect of the HMT on the probability distributions of free proton and neutron kinetic energy in the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ central reaction with MDI interaction at a beam energy of 50 MeV/nucleon.

Figure 4

The probability distributions of free proton and neutron kinetic energy in the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ head-on collisions, with HMT at beam energies of 50 and 140 MeV/nucleon, respectively.

Figure 5

The probability distributions of proton and neutron kinetic energy in the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ central reaction using the MDI interaction with $x=0$ and 1 at beam energy of 140 MeV/nucleon in both FFG and HMT cases.

Figure 6

Effects of the HMT on the differential probabilities as a function of proton and neutron kinetic energy in the ${}^{124}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ head-on collisions with SBKD interaction at a beam energy of 50 MeV/nucleon.

Figure 7

The probability distributions of proton and neutron kinetic energy in ${}^{124}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ central reaction at a beam energy of 140 MeV/nucleon using SKBD and MDI interactions, respectively.