We use an underground counting lab with an extremely low background to perform an activity measurement for the [Formula presented] system with energies down to [Formula presented] MeV, at which the 12C(13C,p)24Na cross section is found to be 0.22(7) nb. The [Formula presented] fusion cross section is derived with a statistical model calibrated using experimental data. Our new result of the [Formula presented] fusion cross section is the first decisive evidence in the carbon isotope systems which rules out the existence of the astrophysical S-factor maximum predicted by the phenomenological hindrance model, while confirming the rising trend of the S-factor towards lower energies predicted by other models, such as CC-M3Y+Rep, DC-TDHF, KNS, SPP and ESW. After normalizing the model predictions with our data, a more reliable upper limit is established for the [Formula presented] fusion cross sections at stellar energies.
|ジャーナル||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|出版ステータス||Published - 2020 2 10|
ASJC Scopus subject areas
- Nuclear and High Energy Physics