Experimental Study Of ¹⁷C

Halo nuclei structure is one of the hot topics in nuclear physics in recent decades.Especially with the continuous development of accelerator technology,people were given a reliable experimental method for the further research of halo nuclear.Halo nuclei usually have some strange features: Large spatial distribution,small separation energies of the valence nucleons,large interaction(or total reaction)cross sections and narrow momentum distributions of the breakup fragments.Measurements of interaction cross sections or total reaction cross sections have been proven to be effective tools to reveal the exotic structure in proton rich nuclei or neutron rich nuclei.Tanihata et al.found the neutron halo structure of 11 Li with this method.Whether there is a halo structure in carbon isotopes has been received great attention,scientists have done a lot of research work for the carbon isotopes.Only 15 C and 19 C has been confirmed to have a halo structure and their single neutron separation energy are small.Studies show,small separation energies of the valence nucleons is a necessary condition of forming halo structure.For neutron rich 17 C,the single neutron separation energy is very small(Sn=0.727MeV).But the double neutron separation energy is high(S2n=4.977Mev).This indicates that the last one neutron is very weakly bound.Therefore we think that the 17 C may also have halo structure.However,recent work on a measurement of interaction cross section at relativistic energy showed no large enhancement associated with a halo structure.But this doesn’t mean there is no halo structure in 17 C.It have been proven to be more sensitive of the nuclear density at the surface because of larger nucleon-nucleon cross sections.So the experimental data at lower energies will be more convincing.But in the low energy region,17C’s experimental data of total reaction cross section or interaction cross section are very scarce.This is also the motivation of our work.Based on this,we have measured the total reaction cross section of 17 C on a 12 C target at 44MeV/nucleon using the transmission method.We compared the calculation results of KOX formula and the current experimental data,we deduced the density distribution of 17 C by fitting the experimental data using the finite-range Glauber model.Theoretical analysis shows that there is a large difference between the calculation results of KOX formula and the present experimental result.With a simple harmonic oscillator(HO)density distribution is not adequate to explain the experimental data.To get a better fit of the data.We choose harmonic oscillator + Yukawa tail density distribution for 17 C to fit the experimental data and the fitting result is perfect.This suggests that the 17 C is likely to have extended density distribution.