Discovery of Neutron-Rich Silicon Isotopes 45,46Si

New isotopes 45,46Si, which extend beyond the most neutron-rich Si isotopes confirmed thus far, have been discovered at the RI Beam Factory at the RIKEN Nishina Center. The isotopes were produced by the in-flight fragmentation reactions of ⁷⁰Zn at 345 MeV/nucleon on a Be target. All the projectile fragments were analyzed and identified using the large-acceptance two-stage separator BigRIPS. Consequently, six ⁴⁵Si events and one ⁴⁶Si event were confirmed. The neutron-bound nature of odd-N⁴⁵Si may have a significant impact on the nuclear stability of neutron-rich proton $sd$-shell nuclei at approximately $N=40$.