Search for a light neutral particle in the decay of the 3.68 MeV state in C

A search is made for a short lived neutral particle, ø, in the decay of the 3.68 MeV (3/2^-) state in ¹³C. No evidence for such a particle with a rest mass in the region of 1.7–2.0 MeV/c² is found with a limit on the branching ratio Γ _ø/Γ_γ7×10 ⁻⁵. An upper limit of 10⁻⁶ is placed for the coupling of such a particle to proton/neutron.