Indications for a bound tetraneutron

Abstract

Using the reaction 7Li(7Li,10C) we tried to populate states in the tetraneutron. A peak in the energy spectrum of identified 10C, which we cannot attribute to a reaction with any other of the target components, corresponds to an excitation of the 10C+4n system of 2.93±0.16 MeV. Under different kinematic conditions an equivalent peak was observed. For a binding energy of the tetraneutron of −2.93 MeV a much larger width than the observed upper limit of Γ<0.24 MeV (mainly due to experimental spread) is expected. Therefore, we favor the interpretation that this peak corresponds to 10C in the first excited state at 3.354 MeV and a tetraneutron with a binding energy of +0.42±0.16 MeV.