About ACCULINNA scientific group
at FLNR JINR, Dubna
Progress in the production of very short lived nuclei and the development of radioactive ion beams (RIBs) provide access to the study of the most exotic
nuclei. Since 1996, when the fragment separator ACCULINNA was built, RIBs became a powerful tool used in the Flerov Laboratory of
Nuclear Reactions (FLNR) in the studies of exotic nuclei.
Within the recent years the ACCULINNA group not only used recognized techniques to RIB research. It proposed, developed, and practically applied a novel
approach, to the investigation of resonant states or nuclei in proximity and beyond the neutron drip-line. This work was not restricted solely to the
derivation of invariant/missing mass spectra. It succeeded to show that, in the experiments performed with certain kinematical settings, correlations
inherent to the reaction products become an extremely rich source of information about the structure of the studied exotic nuclei. A unique technical
feature of the ACCULINNA separator is the availability of intense tritium beams accelerated at the U-400M cyclotron and possibility to work with cryogenic
tritium targets. At the moment it is the only place in the world where the availability of the tritium target and the beam is combined with the RIB
research.
There are several factors which favor to achieve interesting physics results at the ACCULINNA facility. Primary heavy ion beams ( e.g.
7Li, 11 B, 180, 20Ne, 32S, 48Ca) provided by the U-400M cyclotron fall into quite a low
energy domain restricted to 35-55 MeV /amu. However, the record intensities of these beams partly compensate the deficiency in the RIB production rate
inevitable in this case. The higher cross sections inherent to some important nuclear reactions at low RIB energies accessible at ACCULINNA counterbalance
their relatively low intensities. Further, energy range of the exotic beams provided by ACCULINNA is optimal for the nuclear structure studies done by
means of transfer reactions. Due to their transparent mechanism the transfer reactions are well understood and clear explanation becomes available for the
data obtained low (compared to the other in-flight separators) RIB energy provides prerequisite for better energy resolution in the measurements done in
different experimental conditions. Complete kinematical measurements performed for the reactions induced by these beams result in the observation of very
clean, background-free spectra. Essential consequence of such correlation measurements is the possibility of unambiguous spinparity identification for
the observed resonance states. The choice of kinematical conditions selecting specific reaction mechanisms (i.e., direct transfers, quasi-free scattering,
and spin alignment in zero geometry transfers) simplifies data interpretation.