Ternary fission has been investigated by irradiating a natural uranium target with 13.5 MeV deuterons. The energy and angular distributions of ternary alpha particles do not differ from those observed in spontaneous or thermal neutron induced fission. The angle between alpha particles and light fragments has a most probable value of~r 82.1 ~ + 0.6 ~ with a dispersion (FWHM) of A~= 1B.4 ~ +-1,2 ~ The corresponding values of the energy distribution are Em = (14.8 * 0.5)MeV and ~E(FWHM) = (9.1 + 1.1)MeV.'The peak-to-valley ratio of the ternary fission fragment mass distribution is found to increase with increasing alpha energy. For near-symmetric mass division a strong broadening of the angular distribution is observed.Most of the light charged particles (icp) accompanying fission at low excitation energies are long range alpha particles (lra) with a sharply peaked angular distribution. The equatorial emission within a plane perpendicular to the fission axis is attributed to the origin of the alpha trajectories in the very vicinity of the neck, Many detailed investigations of spontaneous and thermal neutron induced ternary fission confirmed this hypothesis and showed the possibility of learning more about the scission point dynamics by studying various correlations of lra and fission fragment (ff) observables.In the present work, in-beam measurements were performed at the Rossendorf cyclotron U-120 by irradiating a natural UO 2 target with i].5 MeV deuterons. Both fission fragments were recorded with a large position-sensitive doubie-grid avalanche counter (DGAC) and a smaller paralielplate avaianche counter (PPAC) arranged perpendicular to the beam axis in 180 ~ geometry ( fig. i). The coincident light particles were identified by a time-of-fIight (TOF) system consisting of a small transmission PPAC and a large surface barrier detector as start and stop/E detectors, respectively. An additional veto PPAC for recording recoil nuclei was arranged under 45 ~ with respect to the beam axis in order to suppress random ff-~ coincidences caused by ~x-particies originating from (d,~)-reactions. Six parameter events consisting of TOFIco, Elco, zITff_ic o, ZITff-ff, Xand Y were recorUed in'list mode bnto magnetic disk.Every single event was off-line transformed into a physical relevant parameter set Mlco, Elco, A~ff_lcp, Mff, ~ff-lco and ~ . Making use-of the Viola systematics,-the ff mass was deduced from the ff TOF-difference corrected for flight path variations. The 4.104 accumulated events were then analyzed by generating different two-dimensional correlation fields. Besides the huge background of random coincidences, about i0 ) true lra events with E~ ii MeV could be identified.
