Publications
Publications within Experimental Nuclear Physics
Research activities
The Subatomic Physics Division at Chalmers University of Technology
conducts a leading, broad programme aiming at studies of light, exotic
nuclear systems in the vicinity of the neutron and proton driplines. The
overall objective is to connect nuclear structure observables to the
underlying constituents, neutrons and protons, as well as addressing
burning topics in nuclear astrophysics and fundamental interactions.
Exotic nuclei exhibit very large beta-decay energies and low
separation energies for particles, or cluster of particles. These
features result in structural peculiarities, like clustering. These
effects do not only serve as a basis for finding the relevant degrees of
freedom in exotic systems, through the separation of energy scales, but
do as well play crucial roles in astrophysical reactions. The
triple-alpha nature of the Hoyle state in 12C is here a classical case but other crucial examples exist, e.g. the proton halo in 8B,
both of which have been studied by us. These open quantum systems pose a
specific challenge for both theoretical and experimental studies since
the coupling to the continuum is a major component to be taken into
account.
Structural phenomena can manifest themselves through the
beta-delayed particle decay modes. The Chalmers group was first to
observe (β2n), (β3n), (βt) and (βd) emission in light neutron-rich
nuclei. The latter decay mode is only present in nuclei with a developed
halo structure, a phenomenon also first suggested by the Chalmers
group. More recently, the unbound nuclei 12,13Li were
identified for the first time in our experimental data from GSI,
demonstrating how even the most exotic nuclear systems at the driplines
can be used as stepping-stones to reach beyond the limits of nuclear
binding. The method of studying exotic unbound systems through
relativistic one-/few-nucleon knockout was pioneered by us and has an
excellent potential also in future, in particular with FAIR-R3B.
The present experimental programme is mainly conducted at two
world-leading research infrastructures; the ISOLDE Facility at CERN and
the heavy-ion accelerator SIS at GSI, Darmstadt. The ISOLDE Facility,
including the REX-ISOLDE post-accelerator, is able to deliver low-energy
beams of radioactive isotopes of more than 70 elements. The
complementary scientific programme at GSI gives access to exotic beams
of all species in the energy range of 200 MeV to 1 GeV/nucleon, produced
in the FRS fragment separator. The experiments at GSI are predominantly
performed using the R3B/LAND setup, being capable of
yielding complete kinematics information. Complementary investigations
are performed using the FRS as a spectrometer, with a secondary reaction
target at the middle focal plane. The combined studies at these
facilities give us a unique chance to get broad information about the
nuclear structure at and even beyond the driplines.
Our main working partners are the R3B-collaboration at
GSI/FAIR and the MAGISOL (Aarhus University in Denmark and IEM-CSIC;
Madrid, Spain) and from ISOLDE and GSI. The work in Gothenburg is
focussed on data reduction and analysis with strong eScience components.
This is combined with theoretical interpretation, both in direct
relation to the available experimental data and for the planning of new
experiments, as well as detector development.
The research infrastructures ISOLDE and GSI are in the process
of evolving; in particular will GSI transform into the international
FAIR (Facility for Antiproton and Ion Research) facility in the coming
years. Within the NUSTAR (Nuclear Structure, Astrophysics and Reactions)
collaboration, the group is deeply involved in developing detection
systems for the next-generation reaction setup for exotic nuclei, R3B.
The group members have as well several key positions within the FAIR
efforts, like Swedish delegate to the FAIR Council, NUSTAR
spokesperson/chair of Board of Representatives, member of the BFC (Board
of FAIR Collaborations), Board Member of SFAIR(Swedish FAIR-consortium)
and Deputy Spokesperson of R3B.