SPIRAL discoveries
A harvest of results on exotic nuclei.
Exotic nuclei are radioactive. They emit radiation spontaneously. The energy of this radiation provides direct information related to their structure.
In 1985, the first nucleus with a neutron halo was discovered. With its unique beams of helium-6 and -8, these nuclei being formed from a helium-4 core surrounded by a "cloud" of either 2 or 4 neutrons, SPIRAL set out to systematically explore these enigmatic structures: | |
| |
The disappearance of nucleon layers
In stable nuclei, protons and neutrons are ordered in a well-defined layer system. The study of exotic nuclei shows that this paradigm is challenged. To gain a better understanding of their behaviour, physicists try to locate these layers by depositing or removing nucleons on, or from, the exotic nuclei produced by SPIRAL. The quivering of the layers they observe could be explained if the neutrons and protons, oriented in opposite directions, were far more strongly attracted to one another than expected.
By causing the exotic nuclei in SPIRAL to revolve using a secondary reaction, physicists are able to determine their shape. This has allowed them to discover that certain exotic krypton nuclei can have, simultaneously, 2 different shapes: prolate and oblate. | ||
Exotic nuclei are created within stars. By measuring their reactions or structures, physicists are able to explain their role in stellar evolution. | ||
Exotic nuclei spontaneously transmute into more stable nuclei, by transforming a neutron into a proton or vice-versa. This is known as Beta radioactivity. This interaction, which is very slow, is known as the weak nuclear force. By trapping exotic nuclei with magnetic fields or lasers, physicists can now conveniently study this fundamental interaction. | ||
