Lifetime Measurements and Deformation in $^{79}$Sr

High-spin states in $^{79}$Sr were produced following the $^{54}$Fe($^{28}$Si, $2pn$) fusion-evaporation reaction using a beam energy of 90 MeV at the Florida State University (FSU) Tandem-Linac facility, and the resulting de-exciting $\gamma$ rays were detected with the FSU Ge array of 10 Compton-suppressed detectors. The $^{54}$Fe target was thick enough so that all of the synthesized nuclei could stop completely in the target, resulting in Doppler-shifted $\gamma$-ray line shapes that could be analyzed using the Doppler-shift attenuation method. In all, 23 lifetimes were measured in three separate band structures using this method, and then used to infer transition quadrupole moments ($Q_t$) and quadrupole deformations ($\beta_2$) using the rotational model. The results show good qualitative agreement with the predictions of both cranked Woods-Saxon (CWS) and projected shell model (PSM) calculations. The band based on a $d_{5/2}$ single-particle orbit, verified in this study through $\gamma - \gamma$ coincidences, intensity measurements, and directional correlation of oriented nuclei (DCO) ratios, was found to have the largest average deformation ($\beta _{2,{\rm ave}} = 0.41$) among the three bands, in agreement with the CWS and PSM predictions.