Mass Resolution for Iron Isotopes in CR-39 Track Detector

Abstract

We have verified the capability of a CR-39 track detector for isotope identification using iron beam from the heavy-ion accelerator of HIMAC at NIRS. The same CR-39 stack was independently exposed to 56 Fe and 55 Fe ions with an energy of 460 MeV/nucleon. Mass resolutions for 56 Fe and 55 Fe ions were determined to be 0.28±0.12 amu and 0.28±0.11 amu in rms, respectively. A detailed analysis of the sources of the mass dispersion in the present mass identification experiment showed that significant errors were caused in the measurements of the surface position and the thickness of CR-39 sheets. By eliminating these errors as much as possible, the mass resolution is expected to be improved to ∼0.20 amu.