Changes in Nuclear Structure of Titanium-48 Observed at Varying Distances

Changes in Nuclear Structure of Titanium-48 Observed at Varying Distances
by Riko Seibo
Tokyo, Japan (SPX) Jul 21, 2024
The world of subatomic particles continues to reveal its secrets as physicists at Osaka Metropolitan University uncover significant insights into the nuclear structure of atoms. Their study, published in Physical Review C, shows that the arrangement of protons and neutrons in an atom's nucleus may vary based on their distance from the center.

Graduate student Maito Okada, Associate Professor Wataru Horiuchi, and Professor Naoyuki Itagaki from the OMU Graduate School of Science conducted a detailed comparison of theoretical models and experimental data. They aimed to determine whether titanium-48, the most prevalent isotope of titanium with 22 protons and 26 neutrons, exhibits a shell model structure or an alpha-cluster structure.

Shell models are characterized by symmetry, while alpha-cluster structures feature alpha particles at the nucleus's periphery, leading to an asymmetrical arrangement. An alpha particle, consisting of 2 protons and 2 neutrons, is identical to a helium nucleus. During alpha decay, this particle is emitted, which in the case of titanium-48, would transform it into calcium-44.

The OMU researchers investigated the impact of high-energy protons and alpha particles colliding with titanium-48. This approach, based on nuclear reaction theories, revealed that proton collisions reflect the nucleus's near-surface structure, whereas alpha particle collisions highlight the structure of the outer regions.

Their findings indicate that titanium-48 transitions from a shell model structure to an alpha-cluster structure depending on the proximity to the nucleus's center.

"These results upend the conventional understanding of nuclear structure and can be expected to provide clues to the a-decay process that occurs in heavy nuclei, which has not been solved for nearly 100 years," Professor Horiuchi enthused, referring to the Gamow theory on nuclear decay. "In the future, we would like to extend the results obtained through this research to take on the challenge of solving issues related to heavier nuclei."

Research Report:Shell-cluster transition in 48Ti