Peak shock temperature (solid red lines) and velocity (solid green lines) for different initial explosive conditions in the 20 M_⊙ progenitor from Ritter et al. (2018b). The purple line represents the logarithm of the quantity ρr³ in the pre-supernova model in arbitrary units. The gray region represents the temperature range for the activation of the γ process, i.e., between 2 GK and 3.5 GK. Note that the saturation of the shock velocity at ∼4.2 M_⊙ at the value of 5 × 10⁹ cm s⁻¹ is due to the artificial cap imposed for viscous forces (see Sect. 2.1).