New research conducted at Oak Ridge National Laboratory has brought forth surprising results that challenge our understanding of atomic nuclei shapes. Led by Timothy Gray, a team of nuclear physicists used radioactive beams of excited sodium-32 nuclei to explore the evolution of nuclear shapes far from stability.
Traditionally, atomic nuclei are classified as either having spherical or deformed shapes. Spherical nuclei resemble basketballs, while deformed nuclei resemble American footballs. The relationship between shapes and energy levels is a topic of great interest in the scientific community. However, nuclear structure models struggle to accurately predict shapes in regions with limited experimental data.
In some cases, traditional models contradict observations for exotic radioactive nuclei. Nuclei that were expected to have spherical ground states turned out to be deformed, and vice versa. This challenges the notion that the ground state determines the shape of excited states.
One intriguing phenomenon is the reversal of quantum states. Normally, the energy of an excited deformed state is higher than that of a spherical ground state. However, for certain exotic nuclei with imbalanced neutron-to-proton ratios, the spherical shape becomes the high-energy state. Yet, these excited spherical states have never been observed. It seems that once the ground state becomes deformed, all the excited states follow suit.
To delve deeper into this mystery, the research team utilized data collected from the Facility for Rare Isotope Beams (FRIB) at Michigan State University. They discovered a long-lived excited state of radioactive sodium-32 with an unusually long lifetime of 24 microseconds. This extended lifetime suggests that something unexpected is happening. If the excited state is spherical, it may have difficulty returning to a deformed ground state.
The study involved collaboration between 66 participants from 20 universities and national laboratories. The experimental setup utilized the FRIB Decay Station initiator (FDSi), a sophisticated multidetector system designed to detect rare isotope decay signatures. The FDSi was able to capture the long-lived excited state of sodium-32 and record its decay through gamma-ray emission.
The results of this study challenge established theories and raise important questions about the evolution of nuclear shapes. Further research is needed to unravel the mysteries of these quantum nucleus shapes and their implications for our understanding of nuclear physics.
FAQ
Q: What are the traditional shapes of atomic nuclei?
A: Atomic nuclei are traditionally classified as having either spherical or deformed shapes. Spherical nuclei resemble basketballs, while deformed nuclei resemble American footballs.
Q: How do shapes and energy levels relate to each other in atomic nuclei?
A: The relationship between shapes and energy levels in atomic nuclei is a topic of interest in the scientific community. However, nuclear structure models struggle to accurately predict shapes in regions with limited experimental data.
Q: What is the phenomenon of quantum state reversal?
A: Quantum state reversal refers to the unexpected role reversal of quantum states in certain exotic nuclei. Normally, the energy of an excited deformed state is higher than that of a spherical ground state. However, for some nuclei with imbalanced neutron-to-proton ratios, the spherical shape becomes the high-energy state.
Q: What is the Facility for Rare Isotope Beams (FRIB)?
A: The Facility for Rare Isotope Beams (FRIB) is a user facility at Michigan State University that is dedicated to the study of rare isotopes. It provides researchers with a unique opportunity to explore various aspects of nuclear physics.
Q: What is the FRIB Decay Station initiator (FDSi)?
A: The FRIB Decay Station initiator (FDSi) is a modular multidetector system used to detect rare isotope decay signatures. It played a crucial role in capturing the long-lived excited state of sodium-32 and recording its decay through gamma-ray emission.