Platinum and gold are believed to be produced when massive neutron stars collide in outer space. The characteristics of these stars remain a mystery, but the solution could be found inside the lead atomic nucleus, one of the tiniest building units on Earth.
Atomic nuclei are the central component of atoms, which are the basic units of matter. They are made up of protons and neutrons, which are held together by the strong nuclear force. The number of protons in the nucleus determines the atomic number of the element, which in turn determines its properties and behavior.
It has proven challenging to unlock the mysteries of the strong force, which controls neutron star interiors, in the atom’s nucleus. The Chalmers University of Technology in Sweden has developed a new computer model that can now deliver solutions.
Researchers from Chalmers reveal a breakthrough in the calculation of the atomic nucleus of the heavy and stable element lead in a recently published paper in the academic journal Nature Physics.
The strong force plays the main role
Even though a neutron star’s size is many kilometers larger than an atomic nucleus, their properties are generally governed by the same physics. The strong force, which holds protons and neutrons together in an atomic nucleus, is the common denominator. A neutron star is likewise prevented from collapsing by the same force.
Despite being a fundamental component in the cosmos, the strong force is challenging to account for in computer models, especially when it comes to heavy, neutron-rich atomic nuclei like lead. As a result, the researchers’ difficult calculations have left them struggling with a lot of unresolved issues.
We predict that the neutron skin is surprisingly thin, which can provide new insights into the force between the neutrons. A groundbreaking aspect of our model is that it not only provides predictions but also has the ability to assess theoretical margins of error. This is crucial for being able to make scientific progress.
Professor Christian Forssén
A reliable way to make calculations
“To understand how the strong force works in the neutron-rich matter, we need meaningful comparisons between theory and experiment. In addition to the observations made in laboratories and with telescopes, reliable theoretical simulations are therefore also needed. Our breakthrough means that we have been able to carry out such calculations for the heaviest stable element lead,” says Andreas Ekström, Associate Professor at the Department of Physics at Chalmers and one of the main authors of the article.
The new computer model from Chalmers, which was created in collaboration with experts in England and North America, now demonstrates the way forward. It allows for highly accurate predictions of the characteristics of the isotope lead-208 and its alleged “neutron skin.”
The thickness of the skin matters
The 126 neutrons that make up an atomic nucleus create the exterior covering, or skin, of the atom. The qualities of the strong force are related to the thickness of the skin. Understanding of how the strong force operates in neutron stars and atomic nuclei can be improved by making predictions about the thickness of the neutron skin.
“We predict that the neutron skin is surprisingly thin, which can provide new insights into the force between the neutrons. A groundbreaking aspect of our model is that it not only provides predictions but also has the ability to assess theoretical margins of error. This is crucial for being able to make scientific progress,” says research leader Christian Forssén, Professor at the Department of Physics at Chalmers.
Model used for the spread of the coronavirus
The researchers merged ideas with pre-existing data from experimental studies to create a new computational model. After that, a statistical technique that had previously been used to simulate the potential spread of the coronavirus was merged with the intricate calculations.
It is now possible to assess several strong force hypotheses using the new model for lead. Predictions for various atomic nuclei, from the weakest to the heaviest, can also be made using the model.
The discovery may result in significantly more accurate simulations of objects like neutron stars and a better understanding of their formation.
“The goal for us is to gain a greater understanding of how the strong force behaves in both neutron stars and atomic nuclei. It takes the research one step closer to understanding how, for example, gold and other elements could be created in neutron stars- and at the end of the day it is about understanding the universe,” says Christian Forssén.
During the study, the researchers worked at the Chalmers University of Technology in Sweden, Durham University in the UK, the University of Washington, Oak Ridge National Laboratory, the University of Tennessee and Argonne National Laboratory in the USA, and TRIUMF and McGill University in Canada.
Isotope: An isotope of an element is a variant with a specific number of neutrons. In this case, it is about the isotope lead-208 which has 126 neutrons (and 82 protons).
