Perspectives of Nuclear Physics in Europe - European Science ...

4.3 Nuclear Structure and Dynamics
time consuming nuclear physics experiments RIBs may
also be available in the future from the ISOL@MYRRHA
facility, proposed to be constructed in Belgium, and
making use of a fraction of the very intense proton beam
from the ADS prototype facility MYRRHA.
The next generation RIB facilities will be able to deliver
beams with several orders of magnitude higher intensity
and higher purity, for a wider variety of radioactive
nuclides. These extremely demanding goals involve a
large number of technological challenges. Important R&D
work was carried out in the past not only at the current
RIB facilities, but also at the ALTO (Orsay), EXCYT (LNS),
IGISOL (JYFL) and LISOL (Louvain la Neuve) facilities.
Thanks to this very intense R&D effort, solutions for many
of these challenges have been found.
Outside Europe several RIB facilities and future
projects exist. The most important running facilities
are the RIB Science Laboratory at RIKEN in Japan and
the ISAC2 facility at TRIUMF in Canada. In the USA a
large community is working towards the construction of
the next-generation FRIB facility which could become
available by the end of this decade. Although healthy
competition exists between these and the European
projects, the long tradition for international collaboration
within nuclear physics gives synergy even across
the continents.
Stable-ion beam facilities in Europe, capable of accelerating
a large variety of ions at high intensity are vital
for the community. They will continue to address major
physics problems at the frontiers of nuclear structure and
reaction studies and are particularly needed to produce
neutron deficient nuclei up to and beyond the proton-drip
line, as well as superheavy elements via fusion evaporation
reactions.
Two categories of stable-ion beam facilities can be
identified:
(i) Accelerator systems capable of delivering a large variety
of ion beams up to 100 pnA for in-beam studies,
where the beam intensity is limited by the detector
counting rates. Such accelerators are in use at JYFL,
LNL and LNS.
(ii) High-intensity beams up to 100 pµA are needed
in off-beam studies of extremely weakly produced
nuclei such as super-heavy elements. In such experiments
the maximum beam intensity is dictated by
the capability of the target to sustain a large power
deposition. Installation of the high-intensity LINAG
within the SPIRAL2 project and a dedicated cw-linac
as proposed at GSI will be milestones in this direction.
Smaller accelerator facilities are needed for specific
experiments, instrument development and testing, to
reach large user communities and provide education
of next-generation researchers from university groups.
Here the accelerators in the emerging countries play
an important role. Their scientific capabilities will be
strongly enhanced by the EWIRA joint research activity
of the EU-IA-ENSAR project.
Instrumentation
Highly efficient and versatile instrumentation is a key
feature in making the best possible use of the precious
rare isotopes produced by the facilities. All large
instrumentation projects in today’s nuclear structure and
reaction research are governed by co-operation in R&D
work between groups, which often represent different
subfields of the community. In the future this approach
is even more vital in order to construct the most versatile
and powerful detection systems for probing exotic nuclei.
They need to combine identification (in A and Z) of the
outgoing reaction products together with detection of
all emitted particles (gamma-rays, electrons, charged
particles, neutrons etc.). The R&D projects are driven
by physics ideas, but the introduction of new innovative
experimental techniques and/or new materials often
reveal unexpected phenomena.
Identification and decay spectroscopy
Having produced a new isotope or element, the first task
is to uniquely identify it. Therefore powerful detection
systems have to be developed for the focal plane of the
separators or spectrometers which often also measure
the decay radiation or can be coupled to other detection
systems. Successful developments for stable-ion beam
facilities such as GREAT (JYFL) or MUSETT (GANIL)
paved the road for new systems with higher granularity
and larger dynamic ranges such as the AIDA implantation
system currently being developed for the Super-FRS.
High-sensitivity gamma-ray detection
High-granularity arrays consisting of Comptonsuppressed
Ge-detectors and various ancillary detection
systems have recently resulted in an unprecedented sensitivity
for spectroscopy and reaction studies. Pioneering
work at RIB facilities has been carried out by employing
the EXOGAM, MINIBALL and RISING (EUROBALL
clusters) arrays at GANIL, ISOLDE and GSI, respectively.
Ge detector arrays comprised of former EUROBALL
detectors have been combined with the high-transmission
magnetic separators, PRISMA at LNL and RITU
at JYFL for measurements with stable-ion beams. The
results at LNL show that multi-nucleon transfer reactions
will serve as a step forward in structure studies of
124 | Perspectives of Nuclear Physics in Europe – NuPECC Long Range Plan 2010