Nucleosynthesis inside an accretion disk in a type II collapsar

Taking into account the increasing mass of a central object through fall-back, we investigated nucleosynthesis inside an accretion disk formed during a core collapse of a massive star. It has been confirmed that the disk is an advection-dominated accretion flow supported by gas or radiation pressure. A sequence of (α, γ) reactions take place and Fe-group elements are produced inside the disk. At the early phase of the fall-back, when O-rich materials inflow, the ejected gas contains abundant 54^Fe and ^56,58Ni. At the late phase the in-coming material is He-rich and the out-going gas is abundant of ⁴⁴Ti as well as Fe and Ni. Provided that the processed gas outflows from the inner region up to the ejection radius, r_ej, we find that the ejected mass of the heavy elements is not very sensitive to r_ej, as long as we take r_ej ≥ 50r _g, because these elements are produced mainly in the region 20-100r_g.