Orateur
Description
More than 80 years after its discovery, a complete description of the fission
process remains a challenge. It is a many-body dynamic problem involving both
microscopic and macroscopic aspects of nuclear matter. Technological breakthroughs
such as the development of Gen-IV reactors and various fundamental aspirations bring
motivation for the scientific community to have a better understanding of this
mechanism. Moreover, new experimental data on exotic fissioning systems that cannot
be probed using direct neutron induced fission are needed to further understand the
fission process.
At GANIL, fission studies using the VAMOS++ large acceptance spectrometer
combined with $^{238}$U beams at energies around the Coulomb barrier allow to populate
such exotic fissioning systems. Also, fission induced by transfer or fusion reaction in
inverse kinematics allows us to obtain isotopic identification (in mass and charge) of
fission fragments. As well, the detection and identification of the target-like residue
provide the characterization of the fissioning systems. Such a combination has been
shown to be a powerful tool to extract post-evaporation isotopic yields and neutron
content (N/Z) that hold the signature of the shell effects at play in the process [1].
Recently, an upgrade of the target-like residue detection systems has been
initiated. For this, the new PISTA (Particle Identification Silicon Telescope Array)
detector has been developed, this last will be located 10 cm away from the target and
will cover angles between 30° and 60°. Allowing one of the fragments to enter VAMOS++
where it will be isotopically identified. PISTA is an array of eight trapezoidal silicon
telescope detectors assembled as in a corolla. Each telescope is composed of two single
sided silicon detectors, 100 μm and 1000 μm thick. The thickness was chosen to
identify light ions up to Oxygen. Target-like nuclei will be identified using (ΔE, E)
technique up to Oxygen isotopes, resulting in the characterisation of the fissioning
system. The high angular granularity of the detector will allow the reconstruction of the
reaction kinematics, thus allowing the reconstruction of the Excitation energy of the
fissioning system. An experiment using $^{238}$U beam at 6 A MeV impinging on a 100 μm
thick $^{12}$C target is schedule in June.Thanks to this new detector, isotopic fission yields
with high statistics per energy bin of about 1 MeV in excitation energy from 6 up to 20
MeV is expected. In this poster, the different features of this new detection system will
be presented. In addition, preliminary results from the experiment scheduled in June
will be presented.
