Measurement of the 18Ne(a,p_0)21Na reaction cross section in the burning energy region for X-ray bursts

TL;DR

This study measures the 18Ne(a,p)21Na reaction cross section at energies relevant to X-ray bursts, providing new experimental data that refines astrophysical models of nucleosynthesis.

Contribution

First experimental determination of the 18Ne(a,p)21Na reaction cross section in the Gamow energy region for X-ray burst conditions.

Findings

Measured cross section at T=2GK is half of theoretical predictions.

Reduced reaction rate impacts breakout conditions from HCNO cycles.

Provides crucial data for modeling nucleosynthesis in X-ray bursts.

Abstract

The 18Ne(a,p)21Na reaction provides one of the main HCNO-breakout routes into the rp-process in X-ray bursts. The 18Ne(a,p_0)21Na reaction cross section has been determined for the first time in the Gamow energy region for peak temperatures T=2GK by measuring its time-reversal reaction 21Na(p,a)18Ne in inverse kinematics. The astrophysical rate for ground-state to ground-state transitions was found to be a factor of 2 lower than Hauser-Feshbach theoretical predictions. Our reduced rate will affect the physical conditions under which breakout from the HCNO cycles occurs via the 18Ne(a,p)21Na reaction.