Constraining the Synthesis of the Lightest p Nucleus ^{74}Se

Area of Science:

• Nuclear astrophysics
• Stellar nucleosynthesis
• Explosive stellar environments

Background:

• The origin of heavy elements, particularly p-nuclei like ^{74}Se, remains a key question in astrophysics.
• The ^{73}As(p,γ)^{74}Se reaction is a significant destruction pathway for ^{74}Se in the gamma (γ) process during stellar explosions.
• Previous studies lacked experimental data for this specific reaction cross section.

Purpose of the Study:

• To experimentally determine the cross section of the ^{73}As(p,γ)^{74}Se reaction.
• To constrain the reaction rate impacting ^{74}Se abundance in explosive stellar environments.
• To investigate the role of this reaction in the production of p-nuclei.

Main Methods:

• Utilized a radioactive ^{73}As beam at specific center-of-mass energies (2.9 and 2.3 MeV/nucleon).
• Measured the total cross section for the ^{73}As(p,γ)^{74}Se reaction.
• Extracted statistical properties of the ^{74}Se compound nucleus.
• Performed Monte Carlo one-zone network simulations to assess the impact on ^{74}Se production.

Main Results:

• Provided the first experimental cross section for the ^{73}As(p,γ)^{74}Se reaction.
• Constrained the reaction cross section within the upper Gamow window relevant to the γ process.
• Simulations indicated that nuclear physics alone does not resolve the overproduction of ^{74}Se in Type II supernovae.

Conclusions:

• The experimental data on the ^{73}As(p,γ)^{74}Se reaction are essential for refining stellar models.
• The observed ^{74}Se overproduction in Type II supernovae likely requires a deeper understanding of astrophysical conditions.
• Further research into the γ process and its environmental dependencies is warranted.