Fusion probability of symmetric heavy, nuclear systems determined from evaporation-residue cross sections

Sahm, C. C.; Clerc, H.‐G.; Schmidt, Karl‐Heinz; Reisdorf, W.; Armbruster, P.; Heßberger, F. P.; Keller, J. G.; Münzenberg, G.; Vermeulen, D.

doi:10.1016/0375-9474(85)90036-3

Cited by 177 publications

(78 citation statements)

References 42 publications

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“…Our previous work described the production of CN near the N = 126 closed shell and suggested that CELD is necessary to reproduce the experimental data [5]. This interpretation was consistent with previous reports discussing the influence of collective effects on reaction products near the N = 126 shell induced by 40 Ar [4], 48 Ca [3], and fragmentation of 238 U [59]. It should be noted, however, that Siwek-Wilczyńska et al calculated each decay width independently for the 16 O + 208 Pb reaction and concluded that CELD is not necessary to reproduce data away from the N = 126 shell [13], although the reaction products in that system are substantially more neutron-rich than the products in the current work.…”

Section: Discussionsupporting

confidence: 89%

“…In these same works [3,4,59], the authors also discussed the lack of evidence for increased survival against fission even though the reaction products have substantial shell stabilizations. The products in the current work are relatively neutron-deficient (see Table I), but still have CN shell corrections of ≈2-5 MeV [45].…”

Section: Discussionmentioning

confidence: 99%

“…Several publications have focused on the production of neutron-deficient compound nuclei (CN) with Z = 83-87 [1][2][3][4][5] and comparisons of the experimental data with model calculations. Various models [6][7][8][9][10][11][12][13] have been proposed to reproduce EvR cross sections by adjusting parameters such as the fission barrier height or including phenomena such as collective enhancements [14] and fission dissipation [15]; however, there is still no consensus on how to best reproduce the experimental data.…”

Section: Introductionmentioning

confidence: 99%

“…A large (≈30%) reduction in the theoretical fission barrier was needed to accurately reproduce the experimental data using the code HIVAP. Sahm et al [3] and Vermeulem et al [4] studied the production of actinide nuclides on and near the N = 126 spherical closed shell but did not observe the expected increase in EvR cross sections due to stabilizing ground-state shell effects.…”

Section: Introductionmentioning

confidence: 99%

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Hot fusion-evaporation cross sections ofSc45-induced reactions with lanthanide targets

et al. 2015

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Background: 45 Sc has rarely been studied as a projectile in fusion-evaporation reactions. The synthesis of new superheavy elements with Z > 118 will require projectiles with Z > 20, and 45 Sc could potentially be used for this purpose.Purpose: Cross sections were measured for the xn and pxn exit channels in the reactions of 45 Sc with lanthanide targets for comparison to previous measurements of 48 Ca reacting with similar targets. These data provide insight on the survival of spherical, shell-stabilized nuclei against fission, and could have implications for the discovery of new superheavy elements. Methods:Beams of 45 Sc 6+ were delivered from the K500 superconducting cyclotron at Texas A&M University with an energy of ≈5 MeV/nucleon. Products were purified using the Momentum Achromat Recoil Spectrometer, and excitation functions were measured for reactions of 160 Gd, 159 Tb, and 162 Dy at five or more energies each. Evaporation residues were identified by their characteristic α-decay energies. Experimental data were compared to a simple theoretical model to study each step in the fusion-evaporation process. 2.4 + − , and 1.8 ± 0.6 μb, respectively. Proton emission competes effectively with neutron emission from the excited compound nucleus in most cases. The α, αn, and α2n products were also observed in the 45 Sc + 162 Dy reaction.Conclusions: Excitation functions were reported for 45 Sc-induced reactions on lanthanide targets for the first time, and these cross sections are much smaller than for 48 Ca-induced reactions on the same targets. The relative neutron-deficiency of the compound nuclei leads to significantly increased fissility and large reductions in the survival probability. Little evidence for improved production cross sections due to shell-stabilization was observed. PACS number(s): 25.70.Gh, 25.70.Jj

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hot fusion-evaporation cross sections ofSc45-induced reactions with lanthanide targets

et al. 2015

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“…To gain insight into the issues involved,we turn to an analysis of the data from a similar, well-studied reaction, that of 124 Sn with 96 Zr [30,31] . There are measured values of the overall "generic" evaporation residue cross sections and data for specific reaction channels.…”

Section: Discussionmentioning

confidence: 99%

Search for inverse fission of uranium

et al. 2012

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Background There is a long term interest in running the fission reaction backwards, i.e., studying the "inverse fission" of uranium. The recent availability of beams of n-rich fission fragments has stimulated interest in this endeavor.Purpose To search for inverse fission in the reactions 124,132 Sn + 100 Mo.Method In the 124 Sn + 100 Mo reaction, evaporation residues were searched for using in beam detection of evaporation residues, in beam α-spectroscopy, and post-irradiation alpha spectroscopy while in the 132 Sn + 100 Mo, the evaporation residue, 230 U, was searched for using post irradiation alpha spectroscopy.Results No evidence for the occurrence of the "inverse fission" reactions was found. The upper limit cross section for the latter reaction is ∼ 550 µb, while the experimental upper limit cross section for the former reaction is about 21 +38 −21 nb. ConclusionsThe intensity of suitable radioactive beams is not high enough at present to detect inverse fission. For the 124 Sn + 100 Mo reaction, the observed upper limits are below the estimates of current models for these reactions, probably due to fusion hindrance.

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Radioelements

2013

Nuclear and Radiochemistry

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Fusion probability of symmetric heavy, nuclear systems determined from evaporation-residue cross sections

Cited by 177 publications

References 42 publications

Hot fusion-evaporation cross sections ofSc45-induced reactions with lanthanide targets

Hot fusion-evaporation cross sections ofSc45-induced reactions with lanthanide targets

Search for inverse fission of uranium

Radioelements

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