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Updated: Jul 13, 2026
07:44
Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems
Published on: April 28, 2016
Evidence for a new low-lying resonance state in 7He.
M Meister1, K Markenroth, D Aleksandrov
1Experimentell Fysik, Chalmers Tekniska Högskola och Göteborgs Universitet, S-412 96 Göteborg, Sweden.
Physical Review Letters
|March 23, 2002
Summary
Researchers studied low-lying resonance states in Helium-7 (7He) by examining Helium-6 (6He) and neutron coincidences. They identified the ground state of 7He as unbound, with an excited state also observed.
Area of Science:
- Nuclear Physics
- Exotic Nuclei Research
Background:
- Investigating the properties of exotic nuclei like Helium-7 (7He) is crucial for understanding nuclear structure and reactions.
- The Helium-8 (8He) nucleus provides a unique opportunity to study neutron-rich systems.
Purpose of the Study:
- To investigate the low-lying resonance states of Helium-7 (7He) formed via fragmentation reactions.
- To determine the energy, width, and spin-parity of these states.
Main Methods:
- Fragmentation of a 227 MeV/nucleon Helium-8 (8He) beam on a carbon target.
- Selection of coincidence events between Helium-6 (6He) nuclei and neutrons, corresponding to the one-neutron knockout channel.
- Analysis of the relative energy spectrum in the 6He+n system.
Main Results:
- Observation of a structure in the relative energy spectrum of the 6He+n system.
- Interpretation of this structure as the ground state of Helium-7 (7He) with quantum numbers Ipi = 3/2(-).
- Determination that the ground state is unbound, with a resonance energy of 0.43(2) MeV and a width of Gamma = 0.15(8) MeV, overlapping with an excited state (Ipi = 1/2(-)) at 1.0(1) MeV with a width of Gamma = 0.75(8) MeV.
Conclusions:
- The study successfully identified and characterized the low-lying resonance states of Helium-7 (7He).
- The findings provide valuable data for nuclear models describing neutron-rich nuclei and reaction mechanisms.
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