Experiments on the synthesis of neutron-deficient kurchatovium isotopes in reactions induced by 50Ti Ions

Oganessian, Yu. Ts.; Demin, A.G.; Iljinov, A. S.; Tretyakova, S.P.; Pleve, A.A.; Penionzhkevich, Yu. É.; Ivanov, M.; Tret'yakov, Yu. P.

doi:10.1016/0375-9474(75)91140-9

Cited by 104 publications

(24 citation statements)

References 10 publications

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“…The listed values are experimental maximum cross sections if excitation functions were measured [15,17,29] or calculated maximum cross sections if only the average thick target production cross sections were measured [14,16,30]. In the latter cases the values listed in Table 2 were deduced from the target thickness and an assumed width of the corresponding excitation function.…”

Section: Resultsmentioning

confidence: 99%

“…The first version is very similar to the device described in [14]. The main part of this device (see Fig.…”

Section: Methodsmentioning

confidence: 96%

“…We have chosen fermium isotopes as compound nuclei because they can be formed by several different target-projectile combinations spanning a wide range of effective fissilities below and above the predicted threshold region for fusion hindrance. Moreover, fermium isotopes have already been produced in 4~ induced reactions on several lead isotopes [14][15][16][17] from 2~ to 2~ allowing to compare the relative contribution of the cross section associated with different evaporation channels. Finally, from an experimental point of view, the spontaneously fissioning nuclides 244Fm (T1/2=3.3 ms) and 246Fm…”

Section: Introductionmentioning

confidence: 99%

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Probing sub-barrier fusion and extra-push by measuring fermium evaporation residues in different heavy ion reactions

G�ggeler¹,

Sikkeland²,

Wirth³

et al. 1984

Z Physik A

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The production of fermium isotopes was attempted by complete fusion of different targets and projectiles spanning a wide range of effective entrance channel fissilities below and above the predicted threshold value Xef fthr~(l'/-v... For the most asymmetric systems where fusion is expected to occur without dynamical hindrance we investigate to what extent the expected amount of sub-barrier fusion contributes to the production of fermium evaporation residues. For increasingly symmetric systems the experimental fusion barriers are found to exceed the fusion barriers predicted by the proximity formalism. The barrier heights are discussed in the framework of both the extra-push model and the surface friction model.

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Section: Resultsmentioning

confidence: 99%

“…The first version is very similar to the device described in [14]. The main part of this device (see Fig.…”

Section: Methodsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Probing sub-barrier fusion and extra-push by measuring fermium evaporation residues in different heavy ion reactions

G�ggeler¹,

Sikkeland²,

Wirth³

et al. 1984

Z Physik A

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“…An advantage of this technique is that the compound nuclei produced have a minimum excitation energy compared with other target-projectile combinations. A number of reactions with heavy ions from 4~ to SaFe have been investigated previously [1][2][3][4][5][6], and the cross sections corresponding to the excitation function maxima have been obtained. An analysis of the shapes of excitation functions for these reactions may provide more detailed information on their mechanism.…”

Section: Introductionmentioning

confidence: 99%

A study of fusion reactions between206, 207Pb nuclei and40Ar ions near the coulomb barrier

et al. 1979

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“…Such a method has already been used repeatedly to synthesice new neutron-deficient isotopes of transfermium elements [2,3], and, quite recently, elements with atomic numbers 106 and 107 E4, 5]. The aim of the present work is to study the mass and energy distributions of the reaction products formed in the bombardment of 243Am with 4~ ions at bombarding energies lying in the range of 214 to 300 MeV.…”

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confidence: 97%

Asymmetric mass distribution from the fusion-fission reaction40Ar+243Am

et al. 1977

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The mass distributions and total c.m. kinetic energies of fission fragments formed in the reaction 4~ + 243Am at bombarding energies of 214, 222, 240 and 300 MeV have been measured using the angular correlation method. Angular distributions and anisotropy for 222 and 300 MeV have also been obtained. A symmetric mass distribution corresponding to the decay of a highly excited compound nucleus was obtained at 300 MeV bombarding energy. However, with decreasing bombarding energy the fission fragment mass distribution becomes asymmetric, the most probable heavy fragment mass being about 200-210 amu.At present it is well known that theoretical extrapolations of nuclear properties to the region of superheavy elements predict a considerable enhancement in nuclear stability in the vicinity of the magic numbers Z=l14 and N=184. Such predictions rest on the assumption that superheavy elements, due to their shell structure [-1], have a high fission barrier (Bs~ 5-10 MeV). At the same time, until recently all the experimental attempts to synthesize superheavy elements by nuclear reactions have led only to estimations of the upper limits for their production cross sections. Based on these data, one can, under certain assumptions, estimate the limiting values of their lifetimes, as a rule, with respect to spontaneous fission. A spontaneous fission half-line is known to depend not only on the fission barrier, but also on the mass coefficients determining the dynamics of the fission process. Therefore, on the basis of the investigations carried out it is difficult to draw more or less definite conclusions concerning the fission barriers of superheavy nuclei. There are sufficient reasons to believe that a fission barrier will exist also in excited nuclei in as much as shell effects remain as the temperature and angular momentum of the nucleus increase. One can therefore admit that at an excitation energy of 20-30 MeV shell effects may be still well pronounced and may influence the decay features. As to the mechanism of the fission of weakly excited superheavy nuclei, this is a problem of special interest to theory.Superheavy nuclei with a relatively low excitation energy (E*i, ~ 20-40 MeV) may, in principle, be produced as compound nuclei in reactions induced by ions heavier than argon. Such a method has already been used repeatedly to synthesice new neutron-deficient isotopes of transfermium elements [2,3], and, quite recently, elements with atomic numbers 106 and 107 E4, 5]. The aim of the present work is to study the mass and energy distributions of the reaction products formed in the bombardment of 243Am with 4~ ions at bombarding energies lying in the range of 214 to 300 MeV. The energies of paired fragments were measured using a correlation method. A collimated 4~ ion beam with a cross section of 2 x 8 mm/ hit a target made of a 100 gg/cm 2 243Am layer deposited onto a 40 gg/cm 2 carbon backing. To detect reaction products we made use of two movable Si(Au) detectors placed at a distance of 80 mm from the target at angles of...

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Experiments on the synthesis of neutron-deficient kurchatovium isotopes in reactions induced by 50Ti Ions

Cited by 104 publications

References 10 publications

Probing sub-barrier fusion and extra-push by measuring fermium evaporation residues in different heavy ion reactions

Probing sub-barrier fusion and extra-push by measuring fermium evaporation residues in different heavy ion reactions

A study of fusion reactions between206, 207Pb nuclei and40Ar ions near the coulomb barrier

Asymmetric mass distribution from the fusion-fission reaction40Ar+243Am

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