Further Evidence for the Nonexistence of Particle-Stable Tetraneutrons

Abstract

A search was made for the occurrence of particle-stable tetraneutrons in the fast-deuteron-induced fission of uranium. This process is known to give a high yield of alphas and tritons. In order to deduce the presence of tetraneutrons, the following hypothetical reactions were investigated: ${\mathrm{N}}^{14}({n}^{4}, n){\mathrm{N}}^{17}$, ${\mathrm{O}}^{16}({n}^{4}, t){\mathrm{N}}^{17}$, ${\mathrm{Mg}}^{26}({n}^{4}, 2n){\mathrm{Mg}}^{28}$, ${\mathrm{Rh}}^{103}({n}^{4}, 2n){\mathrm{Rh}}^{105}$, ${\mathrm{Bi}}^{209}({n}^{4}, n){\mathrm{Bi}}^{212}$ and ${\mathrm{Bi}}^{209}({n}^{4}, 2n){\mathrm{Bi}}^{211}$. No evidence for tetraneutrons was found. The upper limits of tetraneutron yields per alpha obtained from the above reactions are: 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}8}$, 3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$, 3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$, 3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$, 1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$, and 1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}8}$, respectively. It seems reasonable to conclude from these results that the existence of tetraneutrons is most unlikely.