Establishing the Maximum Collectivity in Highly Deformed N=Z Nuclei

Area of Science:

• Nuclear Physics
• Atomic Physics
• Quantum Mechanics

Background:

• Understanding nuclear structure and collectivity is crucial in nuclear physics.
• N=Z nuclei, where the number of protons equals the number of neutrons, exhibit unique nuclear properties.
• Investigating electromagnetic transition strengths provides insights into nuclear collective behavior.

Purpose of the Study:

• To measure the lifetimes of the first excited 2+ states in N=Z nuclei: 80Zr, 78Y, and 76Sr.
• To investigate the maximization of nuclear collectivity in these isotopes.
• To explore the staggering phenomenon in reduced electromagnetic transition strengths.

Main Methods:

• Utilized the gamma-ray line shape method for lifetime measurements.
• Employed nucleon-knockout reactions from intermediate-energy rare-isotope beams.
• Analyzed experimental results using state-of-the-art nuclear density-functional model calculations.

Main Results:

• Successfully measured lifetimes of the first excited 2+ states in 80Zr, 78Y, and 76Sr.
• Extracted reduced electromagnetic transition strengths, offering new information on collectivity.
• Observed significant, unexplained staggering in transition strengths between odd-odd and even-even nuclei.

Conclusions:

• The study provides crucial data on nuclear collectivity in N=Z nuclei.
• The observed staggering effect requires further theoretical investigation.
• Experimental findings are compared with advanced nuclear model predictions.