Application of a parallel plate shower center as trigger detector in (HI,xnγ) reactions

Using the reactions 118Sn(16O,4nsub(γ)) 130C at Esub(Lab) = 80 MeV and 110Pd(24Mg,4nγ) 130Ce at Esub(Lab) = 104 MeV the possibility of the application of a parallel plate shower counter (PPSC) as trigger detector for compound nuclei was studied. Such detector is desirable in order to reduce in compound-nucleus reactions the γ-background from direct reactions and environmental radiation. The PPSC yields to possibilities for the selection of compound nuclei: 1) energy losses 2) time of flight. In the present measurement only the second possibility could be used. But using it it was very well possible to discriminate light radiation-like particles from heavy nuclei by particle-γ and γγ-coincidences. This is exceptionally clearly shown at the particle-γ spectra of the 16O-measurement. In simulation calculations which regard especially neutron evaporation and angular straggling of the compound nuclei it is successfully tried to get predictions about the expected angular distributions and time spectra. But it doesn't succeed to simulate the energy loss spectra. Finally estimates of the expected features of the reaction 34S + 198Pt → 232Pu are presented. It is shown that using this reaction and the present particle-γ-coincidence-instrumentation γ-transitions in 232Pu are measurable. (orig.)