Paper detail

Extracting electric dipole breakup cross section of one-neutron halo nuclei from breakup observables

How to extract an electric dipole (E1) breakup cross section σ(E1) from one- neutron removal cross sections measured by using 12C and 208Pb targets, σ_(-1n)^C and σ_(-1n)^Pb, respectively, is discussed. It is shown that within about 5% error, σ(E1) can be obtained by subtracting Γσ_(-1n)^C from σ_(- 1n)^Pb, as assumed in preceding studies. However, for the reaction of weakly-bound projectiles, the scaling factor Γis found to be two times as large as that usually adopted. As a result, we obtain 13-20% smaller σ(E1) of 31Ne at 250 MeV/nucleon than extracted in a previous analysis of experimental data. By compiling the values of Γobtained for several projectiles, Γ=(2.30 +/- 0.41)\exp(- S_n)+(2.43 +/- 0.21) is obtained, where S_n is the neutron separation energy. The target mass number dependence of the nuclear parts of the one-neutron removal cross section and the elastic breakup cross section is also investigated.