Search for an 80 ms spontaneous fission activity in bombardments of 249Bk with 15N

Nitschke, J. M.; Fowler, Μ. M.; Ghiorso, A.; Leber, Roland; Leino, M.; Nurmia, M.; Somerville, L. P.; Williams, Kimberly E.; Hulet, E.K.; Landrum, J.H.; Lougheed, R. W.; Wild, J. F.; Bemis, C.E.; Silva, R.J.; Eskola, Pirkko

doi:10.1016/0375-9474(81)90564-9

Cited by 24 publications

(3 citation statements)

References 6 publications

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“…Its potential for the prediction of heavy element production in hot fusion reaction has been tested up to the 249Cf(180, 4n)263106 reaction; 263106 being the heaviest nuclide synthesized in a hot fusion reaction. To check the quality of our calculations we have chosen those experimental data from the literature where 'excitation functions' have been measured for 4n evaporation residues; these are the reactions z48Cm(15N, 4n)259103 [39], 249Bk(tSN, 4n)26~ [40], 249Cf(15N, 4n)26~ [41], and 249Cf(180, 4n)26a106 [33,34]. The following corrections have been made on the originally published data: for 260105 the cross sections from [-41] has been increased by 10% according to the existence of a 10% fission branch [37] in this isotope, and for 263106 the cross section from [33] has been increased by a factor of 1.5 taking into account that only spontaneous fission with a branching of 66% has been measured.…”

Section: Results For Fusion Reactions Using Actinide Targetsmentioning

confidence: 99%

How well do we understand the synthesis of heavy elements by heavy-ion induced fusion?

Reisdorf¹,

Schädel²

1992

Z. Physik A - Hadrons and Nuclei

169

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Experimental cross sections to synthesize heavy ion induced fusion reactions are confronted with calculations using the conventional picture of complete fusion after passing the barrier plus statistical deexcitation after complete equilibration. The sensitivity of the calculations to some of the parameters is demonstrated. Despite this sensitivity, a single parameter set is found that reproduces well the large body of data from experiments using actinide targets. By comparison, for the more symmetric entrance channels using targets around 2~we find a fusion hindrance that increases steeply with increasing compound nuclear charge. Predictions for a few reactions of future interest for the synthesis of heavy elements are also presented.

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Section: Results For Fusion Reactions Using Actinide Targetsmentioning

confidence: 99%

How well do we understand the synthesis of heavy elements by heavy-ion induced fusion?

Reisdorf¹,

Schädel²

1992

Z. Physik A - Hadrons and Nuclei

169

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“…In the following years several experiments to establish the half-life of the spontaneous fissioning isotope were performed. Two different results were obtained: half-lives located around 80 ms (Oganessian et a1 1970, Druin et a1 1976, reported from Dubna, and half-lives located near 20ms (Nitschke et al 1981, Sommerville et a1 1985, Hulet 1983b, reported from Berkeley. Very recently, this controversy could be removed, In the reaction 249Bk('5N, 4n)260104 a half-life of 281; ms was measured by Ter-Akopian et a1 (1985).…”

Section: Element 104mentioning

confidence: 99%

Recent advances in the discovery of transuranium elements

Münzenberg

1988

Rep. Prog. Phys.

206

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The heaviest known elements at present, the transactinides, ranging from element 104 to element 109, are the subject of this paper. It will start with a brief historical review on their investigation. A considerable part of this review will be devoted to the experimental methods developed to investigate the isotopes of these artificial elements, where the quantities produced are so small as to be measured in atoms.The major step forward in heavy element research was the finding that the nuclei at the top of the periodic table are unexpectedly stable against spontaneous fission, which has been explained by high ground-state shell effects. The experimental data will be compared with current predictions with the aim of learning about their predictive power.Finally, the limitations of the production of heavy elements by heavy ion fusion will be discussed.

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“…Hundreds of hours of accelerator beam time resulted in the detection of 79 spontaneous fission events, at first attributed to the decay of 0.3-s 26O (104) [97]. However, current work supports a half-life of only 20 ms for this isotope [101].…”

Section: Element 104mentioning

confidence: 71%

Chemistry of the Elements Einsteinium through Element-105

Hulet

1983

Radiochimica Acta

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All known chemical properties of each of the elements 99 (Es) through 105 are reviewed and these properties are correlated with the electronic structure expected for 5/and 6 d elements. A major feature of the heavier actinides, which differentiates them from the comparable lanthanides, is the increasing stability of the divalent oxidation state with increasing atomic number. The divalent oxidation state first becomes observable in the anhydrous halides of californium and increases in stability through the series to nobelium, where this valency becomes predominant in aqueous solution. In this range of elements, the II -<· III oxidation potential decreases from ~ +1.5 to -1.5 volts. These observations lead to the conclusion that, in comparison with the analogous 4/electrons, the 5/ electrons in the latter part of the series are more tightly bound. Thus, there is a lowering of the 5/energy levels with respect to the Fermi level as the atomic number increases.The metallic state of the heavier actinides has not been investigated except from the viewpoint of the relative volatility among members of the series. In aqueous solutions, ions of these elements behave as "normal" trivalent actinides and lanthanides (except for nobelium). Their ionic radii decrease with increasing nuclear charge which is moderated because of increased screening of the outer 6 ρ electrons by the 5/electrons. These relative ionic radii have been obtained from comparisons of the elution position in chromatographic separations.Lawrencium (Lr) completes the actinide series of elements with an electronic configuration of 5 / 14 7 s J 7 p. From Mendeleev's periodicity and Dirac-Fock calculations, the next group of elements is expected to be a ¿/-transition series corresponding to the elements Hf through Hg. The chemical properties of elements 104 and 105 only have been studied and they indeed appear to show the properties expected of eka-Hf and eka-Ta. However, their nuclear lifetimes are so short and so few atoms can be produced that a rich variety of chemical information is probably unobtainable.

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Search for an 80 ms spontaneous fission activity in bombardments of 249Bk with 15N

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Cited by 24 publications

References 6 publications

How well do we understand the synthesis of heavy elements by heavy-ion induced fusion?

How well do we understand the synthesis of heavy elements by heavy-ion induced fusion?

Recent advances in the discovery of transuranium elements

Chemistry of the Elements Einsteinium through Element-105

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