Scientists from the U.S. Division of Energy’s (DOE) Argonne National Laboratory led an international nuclear physics experiment performed at CERN, the European Organization for Nuclear Research, that makes use of novel techniques created at Argonne to study the nature and origin of heavy parts in the universe. The study could provide vital insights into the processes that work together to create unique nuclei, and it’ll inform models of stellar events and the early universe.
The nuclear physicists within the collaboration are the first to monitor the neutron-shell structure of a nucleus with fewer protons than lead and over 126 neutrons — “magic numbers” in the subject of nuclear physics.
At these majestic numbers, of which 8, 20, 28, 50 and 126 are canonical values, nuclei have improved stability, much as the noble gases form with closed electron shells. Nuclei, with neutrons above the number of 126, are largely unexplored because they’re difficult to create. Knowledge of their habits is crucial for understanding the rapid neutron-seize process, or r-process, that produces most of the heavy elements in the universe.
The r-process is thought to take place in extreme stellar conditions corresponding to neutron-star mergers or supernovae. These neutron-rich environments are where nuclei can quickly grow, capturing neutrons to supply new and heavier elements before they decay.
This experiment focused on the mercury isotope 207Hg. The research of 207Hg might shine a light on the properties of its close neighbors, nuclei directly involved in vital features of the r-process.