Abstract
The low-lying structure of semi-magic $^{118}$Sn has been investigated
through the $\beta$-decay of $^{118}$In ($T_{1/2}=4.45$ min) to study shape
coexistence via the reduced transition probabilities of states in the 2p-2h
proton intruder band. This high-statistics study was carried out at TRIUMF-ISAC
with the GRIFFIN spectrometer. In total, 99 transitions have been placed in the
level scheme with 43 being newly observed. Three low-lying $\gamma$-ray
transitions with energies near 285 keV have been resolved from which the
2$^+_{\mathrm{intr.}} \rightarrow 0^+_{\mathrm{intr.}}$ 284.52-keV transition
was determined to have half of the previous branching fraction leading to a
$B(E2;2^+_2\rightarrow 0^+_2)$ of 21(4) W.u. compared to 39(7) W.u. from the
previous measurement. Calculations using $sd$ IBM-2 with mixing have also been
made to compare the experimental $B(E2)$ values to the theoretical values and
to make comparisons to the $^{114,116}$Sn isotopes previously studied using the
same theoretical model.