  We present the results from e+e- coincidence measurements in 238U + 206Pb
collisions at a beam energy of 5.93 MeV/u, using an improved experimental setup
at the double-Orange spectrometer of GSI. The capability of our device to
detect Internal-Pair-Conversion (IPC) e+e- pairs from discrete nuclear
transitions of a moving emitter is demonstrated by investigating the known
1.844 MeV (E1) transition in 206Pb and the 1.770 MeV (M1) transition in 207Pb,
excited via Coulomb excitation and a neutron transfer reaction, respectively.
The Doppler-shift corrected e+- sum-energy spectra show weak lines at the
expected energies with cross sections being consistent with the measured
excitation cross sections of the corresponding $\gamma$ lines and the
theoretically predicted IPC coefficients. No other e+e- sum-energy lines were
found in the measured spectra. The observed transfer cross sections show a
strong dependence on the distance of closest approach (R_min), thus signaling
also a strong dependence on the bombarding energy close to the Coulomb barrier.
