Type: Prelims Only

Physicists in Japan have discovered a new isotope of uranium, with atomic number 92 and mass number 241.

Uranium

• Uranium is a naturally occurring chemical element with the symbol U and atomic number 92.
• It is a heavy metal that is radioactive and found in small quantities in rocks and soils worldwide.
• Uranium has several isotopes, which are atoms that have the same number of protons but different numbers of neutrons.

Isotopes of Uranium

The most common isotopes of uranium are uranium-238 and uranium-235.

1. Uranium-238: It is the most abundant isotope of uranium, accounting for over 99% of natural uranium. It has 92 protons and 146 neutrons in its nucleus. It is not fissile, which means it cannot sustain a nuclear chain reaction. However, it is fertile, which means it can absorb neutrons and undergo radioactive decay to produce other isotopes such as plutonium-239, which is fissile.
2. Uranium-235: It is the second most abundant isotope of uranium, accounting for less than 1% of natural uranium. It has 92 protons and 143 neutrons in its nucleus. Unlike uranium-238, it is fissile, which means it can sustain a nuclear chain reaction. It is used as fuel in nuclear reactors and as the primary material for nuclear weapons.

How are isotopes created?

• Isotopes can be created through natural processes or artificial processes in a laboratory.
• Isotopes are created through natural processes such as radioactive decay, cosmic ray interactions, and nuclear fusion reactions in stars.
• For example, carbon-14 is created in the Earth’s upper atmosphere when cosmic rays interact with nitrogen atoms.
• Isotopes can also be created artificially through nuclear reactions.
• This involves bombarding atoms with particles such as protons, neutrons, or alpha particles, which can change the number of protons and/or neutrons in the nucleus.

How uranium-241 was found?

• To find uranium-241, the researchers accelerated uranium-238 nuclei into plutonium-198 nuclei using the KEK Isotope Separation System (KISS).
• In a process called multinucleon transfer, the two isotopes exchanged protons and neutrons, resulting in nuclear fragments with different isotopes.
• The researchers identified uranium-241 and measured the mass of its nucleus using time-of-flight mass spectrometry.
• Theoretical calculations suggest that uranium-241 could have a half-life of 40 minutes.

Significance of the discovery

• The discovery is significant because it refines our understanding of nuclear physics, particularly the shapes of large nuclei of heavy elements and how often they occur.
• This information helps physicists to design models for nuclear power plants and exploding stars.

Also, what are Magic numbers?

• There is a particular interest in ‘magic number’ nuclei, which contain a certain number of protons or neutrons that result in a highly stable nucleus.
• Lead (82 protons) is the heaviest known ‘magic’ nucleus, and physicists have been trying to find the next element with magic numbers.
• The researchers hope to extend their systematic mass measurements towards many neutron-rich isotopes, at least to neutron number 152, where a new ‘magic number’ is expected.

Conclusion

• The discovery of the new neutron-rich uranium isotope is a major breakthrough in nuclear physics, as it provides essential information for understanding the behavior of heavy elements.
• The researchers’ aim to extend their measurements to other neutron-rich isotopes reflects their commitment to exploring the frontiers of nuclear science and to improve our understanding of the universe.
• Discovering new magic number nuclei through these measurements could have practical applications in designing safer and more efficient nuclear power plants and understanding the properties of exploding stars.