Observation of the Exotic 0_{2}^{+} Cluster State in ^{8}He

Area of Science:

• Nuclear Physics
• Quantum Many-Body Systems

Background:

• Exotic nuclei like Helium-8 (⁸He) are crucial for understanding nuclear structure.
• Theoretical models predict unique cluster structures in neutron-rich systems.

Purpose of the Study:

• To report the first experimental observation of the 0_{2}^{+} state in ⁸He.
• To investigate the predicted condensate-like α+2n+2n cluster structure.

Main Methods:

• Experimental observation of nuclear states.
• Analysis of spin parity and transition strengths.
• Microscopic α+4n model calculations for theoretical support.

Main Results:

• The first observation of the 0_{2}^{+} state in ⁸He is reported.
• This state exhibits spin parity 0⁺, large isoscalar monopole transition strength, and emits correlated neutron pairs.
• Results align with theoretical predictions of the α+4n cluster structure.

Conclusions:

• The findings provide evidence for the condensate-like α+4n cluster structure in ⁸He.
• This study offers new insights into nuclear clustering in neutron-rich systems.
• It also sheds light on pair correlation and condensation in quantum many-body systems.