Cold fusion production and decay of neutron-deficient isotopes of dubnium and development of extraction systems for group V elements.

摘要

Excitation functions for the 1n and 2n exit channels of the 208Pb(51V,xn) 259-xDb reaction were measured. A maximum cross section of the 1 n exit channel of 2070+1100-760 pb was measured at an excitation energy of 16.0 +/- 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660+450-370 pb was measured at 22.0 +/- 1.8 MeV excitation energy. The 1 n excitation function for the 209Bi(50Ti, n)258Db reaction was remeasured, resulting in a cross section of 5480+1730-1370 pb at an excitation energy of 16.0 +/- 1.6 MeV. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.;The extraction of niobium (Nb) and tantalum (Ta) from hydrochloric acid and mixed hydrochloric acid/lithium chloride media by bis(2-ethylhexyl) hydrogen phosphate (HDEHP) and bis(2-ethylhexyl) hydrogen phosphite (BEHP) was studied. The goal of the experiments was to find a system that demonstrates selectivity among the members of group five of the Periodic Table and is also suitable for the study of dubnium (Db, Z = 105). Experiments with niobium and tantalum were performed with carrier (10-6 M), carrier free (10 -10 M) and trace (10-16 M) concentrations of metal using hydrochloric acid solution with concentrations ranging from 1--11 M. The extraction of niobium and tantalum from mixed hydrochloric acid/lithium chloride media by HDEHP and BEHP as a function of hydrogen ion (H+ ) concentration was also investigated. The data obtained are used as the basis to discuss the speciation of niobium and tantalum under the conditions studied and to evaluate possible extraction mechanisms.;The 74Se(18O,p3n) 88gNb excitation function was measured to determine the best energy for producing the 88Nb used in chemistry experiments. A maximum cross section of 495 +/- 5 mb was observed at an 18O energy of 74.0 MeV. The half-life of 88gNb was measured and determined to be 14.56 +/- 0.11 min.