US EPA

1496321 

Journal Article 

Liquid-scintillation spectroscopy of alpha-particle emitters and detection of spontaneous fission events for on-line studies of actinide and transactinide elements 

Wierczinski, B; Eberhardt, K; Herrmann, G; Kratz, JV; Mendel, M; Nahler, A; Rocker, F; Tharun, U; Trautmann, N; Weiner, K; Wiehl, N; Alstad, J; Skarnemark, G 

1996 

1 

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ISSN: 0168-9002 

370 

2-3 

532-538 

English 

10.1016/0168-9002(95)00830-6 

WOS:A1996UC92000036 

http://://WOS:A1996UC92000036
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A liquid-scintillation counting system has been developed for the internal measurement of alpha-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 alpha-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 the system are: (1) detection of spontaneous fission events by larger pulses than produced by alpha-particles; (2) suppression of interfering beta- and gamma-radiation by pulse shape discrimination and pile-up rejection; (3) identification of parent-daughter alpha-alpha- alpha-fission-correlations in decay chains; (4) on-line alpha-energy calibration by spiking the organic phase with 3.96-s Rn-219-1.78-ms Po-215 milked from a Ac-227 source. Tn order to increase the detection efficiency, a unit with three detector cells in series was built and tested with Rn-219 and Rn-220. An on-line model experiment for element 104 was carried out using the alpha-emitter 17-s Hf-161 produced by nuclear fusion of samarium with neon and chemically separated by liquid-liquid extraction.