An improved tracking method for large-acceptance spectrometers in intermediate-energy RIB experiments

An improved tracking method was devised for tracking in large-acceptance spectrometers in intermediate-energy RIB experiments, where drift chamber arrays are deployed both upstream and downstream of a dipole magnet for particle tracking outside the magnetic field. By incorporating into the tracking ${\chi }^2$ the inconsistencies between the tracks entering and exiting the reaction target, and that between the tracks entering and exiting the dipole magnet, the improved tracking method has proved to be effective in eliminating spurious tracks in data analysis of RIB experiments. With the tracking method, enhanced particle identification and reaction cross sections are achieved for neutron-removal products of secondary carbon-isotope beams at around 240 MeV/u in the External Target Facility in HIRFL-CSR.