$\ddot{I}€\to \ddot{I}€\ddot{I}€$ results in nuclei

Abstract

The Crystal Ball ($CB$) collaboration at $BNL$ has recently presented results regarding a study of the $\ddot{I}{€}^{-}A\to \ddot{I}{€}^0\ddot{I}{€}^0{A}^{\prime }$ reaction on $H,D,C,Al$ and $Cu$, using a nearly 4$\ddot{I}€$ detector. Similar results, but for the $\ddot{I}{€}^{+}A\to \ddot{I}{€}^{+}\ddot{I}{€}^{\pm }{A}^{\prime }$ reaction on ${}^{2}H$, ${}^{12}C$, ${}^{40}Ca$, and ${}^{208}Pb$, have been published earlier by the $CHAOS$ collaboration at $TRIUMF$. In this Brief Report a comparison of the results of the two measurements is made, which shows that the $CHAOS$ and $CB$ data share relevant common features. In particular, the increase in strength as a function of A seen in the near-threshold $\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ invariant mass spectra reported by the $CHAOS$ group, is also seen in the $\ddot{I}{€}^0\ddot{I}{€}^0$ CB data, when the results from the two groups are compared in a way which accounts for the different acceptances of the two experiments.

7 pages, 1 figure, accepted for publication in Phy. Rev. C - Brief Report