Orateur
Description
Stretched resonances represent a unique class of high-lying nuclear excitations, characterized by a relatively simple structure. Their wave functions are dominated by a single particle-hole configuration, in which both the particle and the hole occupy orbitals with the highest angular momentum in their respective shells and couple to the highest possible spin value.
In light nuclei, stretched excitations arise from $p_{3/2}→d_{5/2}$, $M4$ transitions and are often located above particle separation thresholds, in the energy continuum region. Information on the properties of these resonances, in particular on their decay branchings, may provide an excellent testing ground for advanced theoretical approaches, such as the Gamow Shell Model (GSM), which incorporate the description of unbound states in the continuum.
Recent experiments have demonstrated the feasibility of populating stretched states in the $^{12}$C, $^{13}$C, $^{14}$N, and $^{16}$O nuclei via inelastic proton scattering at 135 MeV at the Cyclotron Centre Bronowice (CCB) IFJ PAN. By employing γ–proton and particle–proton coincidence techniques, it has become possible to extract information on their decay channels.
The experimental setup consisted of (i) the KRATTA telescope array for detection of scattered protons, (ii) two clusters of the PARIS scintillator array and four LaBr$_3$ detectors for γ-ray measurements, and (iii) four thick DSSD detectors for detection of light charged particles.
The presentation will review the experimental findings on the decays of stretched excitations located around 20 MeV in the $^{12}$C, $^{13}$C, $^{14}$N, and $^{16}$O isotopes. Particular focus will be placed on the preliminary results from the latest measurement at CCB IFJ PAN, which aimed at investigating the decay channels of stretched states in the $^{12}$C nucleus.