Research project P4/18 (Research action P4)
Research in the framework of this IAP aims to develop Radioactive Nuclear Beams, first accelerated at the UCL in 1989, and use them : to carry out experiments of crucial importance to nuclear astrophysics and nuclear physics ; to theoretically interpret the results and to analyse their impact on models of stellar evolution and their contribution to a better knowledge of nuclear structure.
Understanding certain explosive stellar events such as supernovae, novae and X-ray bursts requires knowledge of the properties of certain nuclear reactions involving radioactive nuclei. These properties can be measured with low-energy Radioactive Nuclear Beams produced by the 3 cyclotrons of the UCL and with complementary equipment which either already exists or is being developed at the cyclotrons, such as a separator for the recoil products of these nuclear reactions. Research in this direction includes : improving the characteristics (intensity, energy range) of the existing beams and developing new beams ; constructing and commissioning new equipment ; using the equipment to study nuclear reactions of astrophysical interest. The results of these experiments are interpreted in the framework of models aiming at the description of the nuclei involved in these reactions and their interactions. They are also introduced in the "scenarios" built by theoretical astrophysicists to describe explosive stellar events, and their impact on these scenarios is analysed.
At the present time, one of the main orientations of nuclear physics is the study of "exotic" nuclei, i.e. radioactive nuclei whose composition, in terms of protons and/or neutron number, is very different from that of stable nuclei or nuclei close to the nuclear stability line. Among the new phenomena displayed by these "exotic" nuclei is the existence of a neutron "halo", i.e. a low-density "cloud" of neutrons far from the nucleus. These phenomena can be studied by producing beams of these "halo" nuclei, for example the heavy helium isotope 6He, and studying their interactions with various targets. This work thus includes producing such beams, conducting experiments on their interactions, and interpreting the data theoretically by means of models describing these "halo" nuclei.
The partnership set up in the framework of this IAP has what is needed to succeed in this research in nuclear astrophysics and nuclear physics, as it includes : experimental teams from the UCL, KUL and ULB, each with strong expertise in at least one of the required techniques (production and acceleration of Radioactive Nuclear Beams, study of "exotic nuclei", detectors for g-rays, charged particles, and neutrons, data acquisition and analysis of results) ; and theorists at the ULB, who have developed models of the nuclei and nuclear reactions involved, as well as astrophysical "scenarios" for explosive stellar events.
The work carried out in the framework of this IAP has potential applications in solid state physics.
