Author/Authors :
Birgit Wierczinski، نويسنده , , B. and Eberhardt، نويسنده , , K. and Herrmann، نويسنده , , G. and Kratz، نويسنده , , J.V. and Mendel، نويسنده , , M. and Nنhler، نويسنده , , A. and Rocker، نويسنده , , F. and Tharun، نويسنده , , U. and Trautmann، نويسنده , , N. and Weiner، نويسنده , , K. and Wiehl، نويسنده , , N. and Alstad، نويسنده , , J. and Skarnemark، نويسنده , , G.، نويسنده ,
Abstract :
A liquid-scintillation counting system has been developed for the internal measurement of α-particle energies and the detection of spontaneous fission events on-line in flowing organic solutions resulting from continuous rapid chemical separations by liquid-liquid extraction. The scintillator, dimethyl-POPOP and naphthalene dissolved in toluene, contains the extracting agent, di-(2-ethylhexyl-)-phosphoric acid or dibutylphosphate. An average α-energy resolution of 4,8% FWHM was measured in the energy range 4.78 to 7.69 MeV in stationary as well as flowing organic solutions. Additional features of they system are: (1) detection of spontaneous fission events by larger pulses than produced by α-particles; (2) suppression of interfering β- and γ-radiation by pulse shape discrimination and pile-up rejection; (3) identification of parent-daughter α-α- or α-fission-correlations in decay chains; (4) on-line α-energy calibration by spiking the organic phase with 3.96-s 219Rn-1.78-ms 215Po milked from a 227Ac source. In order to increase the detection efficiency, a unit with three detector cells in series was built and tested with 219Rn and 220Rn. An on-line model experiment for element 104 was carried out using the α-emitter 17-s 161Hf produced by nuclear fusion of samarium with neon and chemically separated by liquid-liquid extraction.
