Collective 2p-2h intruder states in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Sn</mml:mi><mml:mprescripts/><mml:none/><mml:mn>118</mml:mn></mml:mmultiscripts></mml:math> studied via <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> decay of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>In</mml:mi><mml:mprescripts/><mml:none/><mml:mn>118</mml:mn></mml:mmultiscripts></mml:math> using the GRIFFIN spectrometer at TRIUMF
K. Ortner, C. Andreoiu, M. Spieker, G. C. Ball, N. Bernier, H. Bidaman, V. Bildstein, M. Bowry, D. S. Cross, M. R. Dunlop, R. Dunlop, F. H. Garcia, A. B. Garnsworthy, P. E. Garrett, J. Henderson, J. Measures, B. Olaizola, J. Park, C. M. Petrache, J. L. Pore, K. Raymond, J. K. Smith, D. Southall, C. E. Svensson, M. Ticu, J. Turko, K. Whitmore, T. Zidar
Abstract
The low-lying structure of semimagic $^{118}\mathrm{Sn}$ has been investigated through the $\ensuremath{\beta}$ decay of $^{118}\mathrm{In}$ (${T}_{1/2}=4.45$ 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 $\ensuremath{\gamma}$-ray transitions with energies near 285 keV have been resolved from which the ${2}_{\mathrm{intr}.}^{+}\ensuremath{\rightarrow}{0}_{\mathrm{intr}.}^{+}$ 284.52-keV transition was determined to have half of the previous branching fraction leading to a $B(E2;{2}_{2}^{+}\ensuremath{\rightarrow}{0}_{2}^{+})$ 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 $^{114,116}\mathrm{Sn}$ isotopes previously studied using the same theoretical model.