Observation of new neutron-rich Mg, Al, and Si isotopes

We report on the first observation of the neutron-rich isotopes $^{40}$Mg, $^{42,43}$Al, and $^{44}$Si. The rare isotopes were produced by fragmentation of $^{48}${Ca} at 142~MeV/u at NSCL using tungsten targets, and subsequently separated in the A1900 fragment separator. For the discovery of $^{40}${Mg} and $^{42,43}$Al, the A1900 was used in combination with the S800 analysis beam line, resulting in an exceptional selectivity. The comparison of the observed isotopes---especially the odd-odd $^{42}$Al---to established theoretical model calculations suggests that the drip line lies further out to heavier isotopes, at least for aluminum and silicon.