Observation of correlated narrow-peak structures in positron and electron spectra from superheavy collision systems

Abstract

We have observed that the positrons associated with a narrow peak in the positron spectrum from U+Th collisions are correlated with the simultaneous emission of electrons whose energy spectrum also contains a narrow peak. The mean energies and widths of the two peaks are equal within measurement errors. Neither the coincidence peak intensity nor the energy distributions of the positrons and electrons can be accounted for by known nuclear internal conversion processes. Similar observations have also been made in the Th+Th and Th+Cm collision systems.