Scientists Probe the Core of Exotic Nuclei

The forces that keep the protons and neutrons together in the nuclei are called strong nuclear forces and they are actually the strongest forces known. They act on small distances and are caused by a type of boson particles, of the hadron family also known as mesons. Mesons are composed of certain combinations of quarks. Though the strong nuclear forces keep the nuclei of all known chemical elements from disintegrating, they also prevent certain combinations of fundamental particles.

The knowledge regarding the strong nuclear forces is full of contradictions and uncertainties. To better understand the extreme forces that keep the nuclei together, scientists are trying to learn more through the neutron dripline phenomenon.

This physical term refers to the ratio of protons and neutrons that can be put together in a single nucleus before it becomes unstable and splits spontaneously by radio emission. Through this process, the scientists want to find out how many atomic nuclei exist in the universe and what is the process through which they are created. The current periodic table of elements contains a total of 118 elements, out of which only one predicted element hasn't yet been observed.

To study the neutron dripline phenomenon, physicists created, after twenty years of trying, a magnesium 40 isotope with 12 protons and 28 neutrons. Nevertheless the most surprising discovery was made when two other isotopes were created, aluminum 42 and aluminum 43, previously predicted to be too unstable to exist.

Though there are 118 chemical elements known to mankind, the study of the dripline phenomenon has only been studied on the first eight elements.

Earlier this year, the team at the National Superconducting Cyclotron Laboratory, conducted a similar experiment with a beam of calcium nuclei traveling at a speed half of that of the light, by smashing them into a tungsten target, which produces various other nuclei and several particles. Only one in the trillions of resultant nuclei was the one searched by the scientists. Such experiments are extremely difficult, due to the small distances the physicists are working with and they produce the nuclei with the exact number of protons while leaving the neutrons untouched is as hard as balancing a metal sphere on a pin head.

The particles are being filtered out of the particle accelerator with the help of a complex system of magnets and it takes over eleven days to detect the desired particles. Through the creation of the three new isotopes, the researchers showed that the dripline phenomenon was not very well understood and there is still much to learn about the behavior and interactions of the particles that compose the atomic nuclei.

For heavier elements with a nuclei already close to the dripline, the team estimates that to create new isotope to detect the dripline the experiments could be 100 to 1000 times harder and requires extremely powerful equipment and a lot of time. The magnesium 40 isotope took eleven days to create and with the current technology, the creation of the magnesium 42 isotope would probably take about three years of work.