What the study found
The study found that the proton-capture excitation function for oxygen-20 and hydrogen-1 shows oscillatory behavior near the barrier, with broad peaks about 50-100 keV wide. The authors interpret this as evidence for one or more low-angular-momentum quasi-bound states in fluorine-21.
Why the authors say this matters
The authors suggest this result helps probe the existence and character of low-angular-momentum quasi-bound states in fluorine-21. They also conclude that the oscillatory pattern may indicate that the quasi-bound state in fluorine-21 shares vibrational character with the first excited 2+ state of oxygen-20, meaning a state with angular momentum and positive parity.
What the researchers tested
The researchers used a (p,n) reaction and an active target detector to measure the capture excitation function for oxygen-20 plus hydrogen-1 for the first time. They compared the measurements with one-channel coupled-channel calculations, and with R-matrix coupled-channel calculations that also included the first excited 2+ state of oxygen-20.
What worked and what didn't
The one-channel coupled-channel calculations agreed reasonably well with the overall excitation function, but they overpredicted the cross section at the lowest measured energies and did not reproduce the observed oscillations. The R-matrix coupled-channel calculations including the first excited 2+ state did produce oscillatory behavior that roughly matched the observed oscillations in both size and position.
What to keep in mind
The abstract does not describe detailed limitations beyond the models' mismatch at the lowest energies and the failure of the simpler calculations to reproduce the oscillations. The findings are specific to the measured oxygen-20 plus hydrogen-1 capture excitation function and the models compared in this study.
Key points
- The proton-capture excitation function for oxygen-20 and hydrogen-1 was measured for the first time.
- Near the barrier, the capture cross section showed broad oscillatory peaks about 50-100 keV wide.
- The oscillations were interpreted as evidence for low-angular-momentum quasi-bound states in fluorine-21.
- One-channel coupled-channel calculations matched the overall trend but missed the oscillations and overpredicted the lowest-energy cross section.
- Including the first excited 2+ state of oxygen-20 in R-matrix coupled-channel calculations produced oscillations that roughly matched the data.
Disclosure
- Research title:
- Oscillations observed in proton capture by oxygen-20
- Authors:
- H. Desilets, Rohit Kumar, R.T. Desouza, S. Hudan, C. Ciampi, A. Chbihi, K.W. Brown, Varinderjit Singh, B. Pinheiro, J.L. Ferreira, J. Lubian
- Institutions:
- Centre National de la Recherche Scientifique, Centre National de la Recherche Scientifique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Grand Accélérateur National d'Ions Lourds, Grand Accélérateur National d'Ions Lourds, Indiana University Bloomington, Indiana University Bloomington, Indiana University Bloomington, Indiana University Bloomington, Laboratoire National Henri Becquerel, Laboratoire National Henri Becquerel, Michigan State University, Punjab Technical University, Universidade Federal Fluminense, Universidade Federal Fluminense, Universidade Federal Fluminense
- Publication date:
- 2026-03-08
- OpenAlex record:
- View
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