# Energy Acceptance of the St. George Recoil Separator

## TL;DR

The paper evaluates the energy acceptance of the St. George recoil separator, confirming its capability to accurately measure low-energy ($ ext{ extalpha}$,$ extgamma$) reactions relevant to astrophysics, by testing with various primary beams.

## Contribution

It demonstrates that the St. George recoil separator meets design specifications for energy acceptance, validating its use in astrophysical reaction measurements.

## Key findings

- St. George's energy acceptance covers the phase space of recoils from key reactions.
- Performance tests with helium, hydrogen, neon, and oxygen beams confirm suitability.
- Separator meets the required specifications for low-energy astrophysical measurements.

## Abstract

Radiative alpha-capture, ($\alpha,\gamma$), reactions play a critical role in nucleosynthesis and nuclear energy generation in a variety of astrophysical environments. The St. George recoil separator at the University of Notre Dame's Nuclear Science Laboratory was developed to measure ($\alpha,\gamma$) reactions in inverse kinematics via recoil detection in order to obtain nuclear reaction cross sections at the low energies of astrophysical interest, while avoiding the $\gamma$-background that plagues traditional measurement techniques. Due to the $\gamma$-ray produced by the nuclear reaction at the target location, recoil nuclei are produced with a variety of energies and angles, all of which must be accepted by St. George in order to accurately determine the reaction cross section. We demonstrate the energy acceptance of the St. George recoil separator using primary beams of helium, hydrogen, neon, and oxygen, spanning the magnetic and electric rigidity phase space populated by recoils of anticipated ($\alpha,\gamma$) reaction measurements. We found the performance of St. George meets the design specifications, demonstrating its suitability for ($\alpha,\gamma$) reaction measurements of astrophysical interest.