Tetraneutron ($^4n$) has come back in the limelight, because of recent observation of a candidate resonant state at RIBF. We propose to investigate the pion double charge exchange (DCX) reaction, i.e. $^4\mathrm{ He}({ \pi}^- , { \pi}^+)$, as an alternative way to populate tetraneutron. An intense ${ \pi}^-$ beam with the kinetic energy of ~850 MeV, much higher than that in past experiments at LAMPF and TRIUMF, will open up a possibility to improve the experimental sensitivity of the formation cross section, which will be much smaller than hitherto known DCX cross sections such as $^9\mathrm{ Be}({ \pi}^-, { \pi}^+)^9\mathrm{ He}\ (g.s.)$.
Categories: nucl-ex nucl-th