Orateur
Description
The existence of tetra-neutron ($^{4}$n) has been a long-standing question in nuclear physics and few-body neutron systems are of great interest for understanding nuclear forces and the structure of neutron-rich matter. Since the beginning of the century, the discovery of possible candidate for the $^{4}$n state, has been reported several times. However, it triggered a lot of debate about the theoretical interpretation of the results. Assuming that the $^{4}$n state observed is a (T=2, T$_z$=2) and due to the isospin symmetry, it should exist an isobaric analog state (IAS) (T=2, T$_z$=1) in $^{4}$H nuclei. We proposed to study indirectly the $^{4}$n system via the IAS in $^{4}$H nuclei through $^{6}$He(p,$^{3}$He)$^{4}$H reaction. If such a state is observed, it will allow to add more input to current theoretical description of neutral nuclei.
The experiment was performed at GANIL facility using the LISE spectrometer in 2025 beam time. A secondary beam of $^{6}$He at 50 MeV/u was produced by fragmentation of a primary beam of $^{13}$C at 60 MeV/u on a Be target. The beam was transmitted to the experimental setup consisting of a reaction target (CH2 at 10 mg/cm$^2$) placed in the center of the four MUST2 telescopes (Silicon strip detectors coupled to CsI scintillators) and a simplified Zero Degree Detection with only plastic scintillators supplemented by a plastic scintillator placed upstream the target for normalization.
Both results from $^{6}$He(p,t)$^{4}$He useful for calibration purpose and from $^{6}$He(p,$^{3}$He)$^{4}$H will be presented. For the latter, the decay products of $^{4}$H are identified in MUST2 so that the excitation energy spectrum for each decay channel have been extracted. They will be compared with phase space calculations. Preliminary results concerning the IAS of the $^{4}$n will be presented.