On the momentum correlation of (e +e -) pairs observed in U + U and U + Pb collisions
Abstract
First results on the energy and angular dependence of the (e +e -) pairs, emitted from U + U and U + Pb collisions at a beam energy of 5.9 MeV/u, are presented. The (e +e -) coincidence measurements were carried out utilizing a double-Orange ß-spectrometer, which allows to determine the momentum vectors of the positrons and electrons and, hence, their opening angle θ e +e -. The (e +e -) sum-energy spectrum obtained for θe+e-=(180±20)°, which is equivalent to an invariant mass spectrum, indicates multiple-line structures in the energy range between 500 keV and 950 keV for both collision systems. The most pronounced line appears at a sum energy of ∼ 810 keV, corresponding to an invariant mass of ∼ 1.83 MeV/ c2. No evidence for line structures was found for angles 40° ⩽ θ e +e - ⩽ 170°. The energies of the lines are consistent with our previous observations in the single p positron spectra.
- Publication:
-
Physics Letters B
- Pub Date:
- February 1989
- DOI:
- 10.1016/0370-2693(89)90466-8
- Bibcode:
- 1989PhLB..218...12K