Nuclear Contact Times in Dissipative Heavy Ion Collsions Measured Via γ-Ray Spectroscopy

Electron spectra have been measured for elastic and dissipative U + Au collisions at 8.6 MeV/u and analysed within a simple schematic model which describes γ-ray emission in the presence of a nuclear contact time and a total kinetic energy loss (TKEL). A nearly linear dependence of the mean nuclear contact time τ and TKEL was found, reaching τ = 1.1 * 10-21 s with a variance σ = ±0.4 * 10-21 s for a TKEL of (400 ± 50) MeV.

WITHDRAWN: A scintillator based time-of-flight hodoscope with a new type of emitter follower divider

Correlated e+ e− peaks observed in heavy-ion collisions

Abstract Three very narrow e + e − sum-energy peaks around 610, 750, and 810 keV have been observed in U+Th as well as in U+Ta collisions at beam energies around the Coulomb barrier. As no processes involving conventional atomic and nuclear physics were found to describe their origin, the data were in particular confronted with the hypothesis that the lines are due to the two-body decay of neutral objects in an e + e + pair. Although the 810 keV sum-energy line observed in U+Th is consistent with the prompt two-body e + e − decay of a neutral object if created nearly at rest in the heavy-ion center-of-mass system, the other lines require at least a considerably more complicated scenario if …