Discovery of doubly magic 48Ni

Area of Science:

• Nuclear Physics
• Isotope Production
• Nuclear Structure

Background:

• Investigating neutron-deficient isotopes is crucial for understanding nuclear stability.
• Doubly magic nuclei provide key benchmarks for nuclear structure theories.
• The limits of nuclear chart exploration are constantly being pushed by experimental advancements.

Purpose of the Study:

• To synthesize and identify very neutron-deficient isotopes using projectile fragmentation.
• To observe the doubly magic nucleus 48Ni for the first time.
• To determine the properties of 48Ni, including its isospin projection and half-life.

Main Methods:

• Utilized the SISSI/LISE3 facility at GANIL for experiments.
• Employed projectile fragmentation of a 58Ni beam at 74.5 MeV/nucleon.
• Analyzed data from a 10-day experiment to identify produced isotopes.

Main Results:

• Successfully identified 287 42Cr, 53 45Fe, 106 49Ni, and 4 48Ni isotopes.
• Unambiguously identified the doubly magic nucleus 48Ni, a novel discovery.
• Established 48Ni as the most proton-rich isotope with T(z) = -4.

Conclusions:

• The discovery of 48Ni represents a significant advancement in exploring the nuclear chart.
• 48Ni is likely the last doubly magic nucleus with classical shell closures accessible to current facilities.
• A lower limit for the half-life of 48Ni was determined to be 0.5 μs.