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Observation of the 11N ground state
Oliveira1, Lepine-Szily, Bohlen
1IFUSP-Universidade de Sao Paulo, CP 66318, 05389-970 Sao Paulo, Brazil and CEBES-Centro de Ciencias Exatas, Biologicas e da Saude, Universidade de Sorocaba, Sorocaba, Brazil.
Physical Review Letters
|September 16, 2000
Summary
Researchers observed the ground state and six excited states of the proton-rich nucleus 11N using a multinucleon transfer reaction. The experimental width of the ground-state resonance was found to be narrower than theoretical predictions.
Area of Science:
- Nuclear Physics
- Exotic Nuclei Research
- Nuclear Spectroscopy
Background:
- Proton-rich nuclei are crucial for understanding nuclear stability limits.
- The nitrogen-11 (11N) nucleus is an unbound, exotic system relevant to nuclear astrophysics.
- Previous studies on 11N have been limited, necessitating further experimental investigation.
Purpose of the Study:
- To experimentally observe and characterize the ground state and excited states of the 11N nucleus.
- To determine the energy levels and resonance properties of 11N.
- To compare experimental findings with theoretical predictions for nuclear structure.
Main Methods:
- Utilized the multinucleon transfer reaction 10B(14N,13B)11N.
- Conducted experiments at 30A MeV incident energy at Grand Accelerateur National d'Ions Lourds (GANIL).
- Analyzed the spectrum of 13B ejectiles to identify resonances corresponding to 11N states.
Main Results:
- Observed the ground state and six excited states of 11N as well-defined resonances.
- Localized excited states at excitation energies: 1.63(5), 2.16(5), 3.06(8), 3.61(5), 4.33(5), 5.98(10), and 6.54(10) MeV above the 10C+p threshold.
- Determined the ground-state resonance mass excess to be 24.618(50) MeV and found its experimental width to be smaller than theoretical predictions.
Conclusions:
- The study provides the first detailed observation of multiple energy levels in 11N.
- Experimental data on 11N's properties offer crucial benchmarks for nuclear models.
- Discrepancies between experimental widths and theoretical predictions highlight areas for refinement in nuclear structure theories.