Researchers synthesize new plutonium isotope for the first time

The study explores "magic numbers" of protons and neutrons - specific numbers that lead to extra stability in atomic nuclei. These magic numbers include values like 2, 8, 20, and 126. Prior research indicated that the neutron shell closure at 126 appears to weaken in elements up to uranium. However, it remains unclear if this weakening extends into the transuranium elements, such as plutonium.

"We have discovered the presence of the shell closure in neptunium isotopes through a series of experiments. However, due to the absence of experimental data, the robustness of this closure in plutonium isotopes remains unknown," explained Prof. GAN Zaiguo from IMP.

To address this gap, researchers at IMP, using the Heavy Ion Research Facility in Lanzhou (HIRFL), synthesized plutonium-227 through a fusion evaporation reaction. This isotope is highly neutron-deficient and is the first plutonium isotope ever discovered by Chinese scientists. This breakthrough adds plutonium-227 as the 39th new isotope discovered by IMP.

The team observed nine decay chains and measured the alpha-particle energy and half-life of plutonium-227, with values of approximately 8191 keV and 0.78 seconds, respectively. These measurements align closely with known data on other plutonium isotopes.

Moving forward, the research team intends to focus on lighter plutonium isotopes, which may provide further insight into the robustness of the neutron shell closure at 126 in plutonium. "The newly discovered plutonium-227 is still seven neutrons away from the magic number of 126," said Dr. YANG Huabin, the study's lead author. "To study the robustness of the shell closure in plutonium, it is necessary to continue research on even lighter plutonium isotopes, including plutonium-221 to plutonium-226."

Research Report:Alpha decay of the new isotope 227 Pu