In a collaborative effort, researchers from various institutions including the Variable Mode Spectrometer (VAMOS) group at GANIL in France, the AGATA collaboration, and the Gammasphere facility at Argonne National Laboratory in the U.S. have delved into the nuclear structure of neutron-rich Lanthanum isotopes. Their findings, published in the journal Physical Review Letters, shed light on the behavior of these isotopes beyond the N=82 shell closure, with potential implications for understanding nuclear structure and stability in the context of energy production and nuclear waste management.
The team, led by Dr. A. Navin and Dr. E. H. Wang, investigated the high spin excited states of Lanthanum isotopes 140 to 143, which were populated in fission reactions. They employed two complementary methods to measure the prompt gamma-ray transitions. The first method involved coincidence measurements with isotopically identified fragments produced in the fission of a uranium-238 and beryllium-9 system, using the VAMOS++ and AGATA spectrometers. The second method utilized high statistics three-fold and four-fold gamma-gamma coincidence data from the spontaneous fission of californium-252, using the Gammasphere spectrometer.
The researchers reported the first identification of a pair of parity doublet structures in Lanthanum-143, as well as new high spin level structures in Lanthanum-140 to 142. These findings were interpreted using the systematics of neighboring odd-Z nuclei above the Z=50 shell closure and large-scale shell model calculations. Notably, the results indicated the presence of stable octupole deformation in Lanthanum-143. The excitation energy patterns and their comparison with neighboring isotones suggested a transition from single particle structures to an alternating parity rotational band structure in the Lanthanum isotopic chain as one moves away from the N=82 closed shell.
The practical applications of this research for the energy sector are primarily indirect but significant. Understanding the nuclear structure and stability of these isotopes can contribute to the development of advanced nuclear fuels and the management of nuclear waste. By comprehending the behavior of neutron-rich isotopes, researchers can better predict the outcomes of nuclear reactions and improve the safety and efficiency of nuclear power plants. Additionally, this knowledge can aid in the design of more effective nuclear waste disposal strategies, ensuring the long-term sustainability of nuclear energy.
In summary, the research conducted by Dr. Navin, Dr. Wang, and their colleagues provides valuable insights into the nuclear structure of neutron-rich Lanthanum isotopes. Their findings not only advance our fundamental understanding of nuclear physics but also hold practical implications for the energy industry, particularly in the realm of nuclear power and waste management.
This article is based on research available at arXiv.