Speaker
Prof.
Susumu Shimoura
(Center for Nuclear Study, University of Tokyo)
Description
We have found a candidate tetraneutron resonant state
via a double-charge exchange (DCX) reaction $^4$He($^8$He,$^8$Be) at 190 $A$ MeV
by using the SHARAQ spectrometer at the RIBF facility in RIKEN$^{1)}$.
Production mechanism with kinematical consideration for the present exotic reaction
is introduced and analysis for obtaining missing-mass spectrum is presented.
The observed missing-mass spectrum consists of a continuum consistent with a prediction assuming direct decay from a wave packet produced just after the DCX reaction and
a peak just above the 4n threshold.
The energy of the peak is 0.83$\pm$0.65(stat.)$\pm$1.25(syst.) MeV with a significance
level of 4.9$\sigma$,
which is a candidate of a tetraneutron resonance.
Three-body forces relevant for formation of tetraneutron resonance are discussed
for consistent understanding of few-body systems.
Further experimental approaches for the tetra-neutron system at the RIBF are also shown.
[1] K. Kisamori et al., Phys. Rev. Lett. **116**, 052501 (2016)
Primary authors
Dr
Keiichi Kisamori
(RIKEN Nishina Center)
Prof.
Susumu Shimoura
(Center for Nuclear Study, University of Tokyo)
