Search for sharp lines ine+-e−coincidences from positrons on Th

Abstract

Two mini-orange spectrometers were used to view ${\mathrm{e}}^{+}$-${\mathrm{e}}^{\mathrm{-}}$ pairs from a positron source and a Th scatterer from opposite directions, 180° apart. No statistically significant evidence for peaks previously reported was found in the coincidence spectra.