The influence of experimental setup on the spectroscopy investigation of ¹⁴Be by Coulomb breakup reaction

The two-body core+$2n$ cluster structure was implemented to describe the two-neutron halo nucleus $^{\mathrm{14}}\mathrm{Be}$, where the core$^{\mathrm{12}}\mathrm{Be}$ was assumed inert and at ground state and the dineutron was assumed at pure $2S_0$ state. Based on such a structure the three-body continuum-discretized coupled-channel (CDCC) calculation was successfully used to deal with the $^{\mathrm{14}}\mathrm{Be}$ breakup reactions of $^{\mathrm{14}}\mathrm{Be}+^{\mathrm{12}}\mathrm{C}$ at 68~MeV/nucleon and $^{\mathrm{14}}\mathrm{Be}+ $Pb at 35~MeV/nucleon.Consequently, we modeled the kinematically complete measurement experiment of $^{\mathrm{14}}\mathrm{Be}$ (35~MeV/nucleon) Coulomb breakup at a lead target with the help of Geant4. From the simulation data the relative energy spectrum was constructed by the invariant mass method and $B(E1)$ spectrum was extracted using virtual photon model. The influence of the target thickness and detector performance on the spectroscopy was investigated.