Related Experiment Videos
Enhanced core polarization in (70)Ni and (74)Zn.
O Perru1, O Sorlin, S Franchoo
1Institut de Physique Nucléaire, IN2P3-CNRS, F-91406 Orsay Cedex, France.
Physical Review Letters
|June 29, 2006
Summary
Researchers measured transition probabilities in neutron-rich Zinc-74 and Nickel-70 nuclei. Unexpectedly large values in Nickel-70 suggest added neutrons strongly polarize the proton core, potentially weakening magicity in Nickel-78.
Area of Science:
- Nuclear physics
- Atomic nuclei structure
- Quantum mechanics
Background:
- Understanding nuclear structure and stability is crucial in nuclear physics.
- Neutron-rich isotopes near closed shells provide unique insights into nuclear forces.
- The doubly magic nucleus Nickel-78 (Ni-78) is a key subject of nuclear structure studies.
Purpose of the Study:
- To measure reduced transition probabilities B(E2) for neutron-rich Zinc-74 (Zn-74) and Nickel-70 (Ni-70) nuclei.
- To investigate the influence of added neutrons on nuclear polarization and shell structure.
- To explore potential weakening of magicity in Ni-78.
Main Methods:
- Coulomb excitation experiments using a Lead-208 (Pb-208) target at intermediate energies.
- Production of exotic nuclei (Zn-74, Ni-70) via heavy-ion interactions (Germanium-76 beam on Beryllium target).
- Analysis of reduced transition probabilities B(E2;0(+) --> 2(+)(1)).
Main Results:
- Measured B(E2) values for Zn-74 and Ni-70.
- Observed an unexpectedly large B(E2) value for Ni-70 (42 neutrons).
- Demonstrated strong polarization of the proton core (Z=28) by neutrons beyond N=40.
- Observed a continued rise in B(E2) values for the Zn isotopic chain up to Zn-74 (44 neutrons).
Conclusions:
- Added neutrons beyond N=40 significantly polarize the Z=28 proton core.
- The monopole interaction between neutrons in g(9/2) and protons in f(7/2)/f(5/2) orbitals enhances core polarization in Ni-70.
- This enhanced polarization may lead to a weakening of the predicted magicity of Ni-78.