Experimental Evidence for Hyperdeformed States in U Isotopes

Krasznahorkay, A.; Hunyadi, M.; Harakeh, Mohsen; Csatlós, M.; Faestermann, T.; Gollwitzer, A.; Graw, G.; Gulyás, J.; Habs, D.; Hertenberger, R.; Maier, H. J.; Máté, Z.; Rudolph, Dirk; Thirolf, P. G.; Tímár, J.; Valnion, B. D.

doi:10.1103/physrevlett.80.2073

Cited by 85 publications

(60 citation statements)

References 28 publications

(31 reference statements)

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“…The fission probability and the angular distribution of the fragments support the hypothesis of hyperdeformed states lodging in a third well in several Th and U isotopes [1][2] . In fusion reactions [3][4] performed to produce superheavy elements, transfer reaction events correspond to decay of semi-equilibrated systems from an external potential pocket.…”

Section: Introductionmentioning

confidence: 60%

Multiple-humped fission and fusion barriers of actinide and superheavy elements

Royer¹,

Bonilla²

2007

J Radioanal Nucl Chem

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The energy of a deformed nucleus has been determined within a Generalized Liquid Drop Model taking into account the proximity energy, the microscopic corrections and quasi-molecular shapes. In the potential barrier a third peak exists for actinides when one fragment is close to a magic spherical nucleus while the other one varies from oblate to prolate shapes. The barrier heights and half-lives agree with the experimental data. The different entrance channels leading possibly to superheavy elements are studied as well as their α-decay.

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Section: Introductionmentioning

confidence: 60%

Multiple-humped fission and fusion barriers of actinide and superheavy elements

Royer¹,

Bonilla²

2007

J Radioanal Nucl Chem

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“…2 discovered 3-6 class of long-lived high spin isomeric states in the second minimum (superdeformed (SD) minimum) 11,12 and/or in the third minimum (hyperdeformed (HD) minimum) [13][14][15] of the nuclear potential energy when plotted as a function of deformation. This result motivated us to search for long-lived superactinide elements in natural materials.…”

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confidence: 99%

EVIDENCE FOR THE POSSIBLE EXISTENCE OF A LONG-LIVED SUPERHEAVY NUCLEUS WITH ATOMIC MASS NUMBER A = 292 AND ATOMIC NUMBER Z ≅ 122 IN NATURAL Th

Marinov

Rodushkin²,

Kolb

et al. 2010

Int. J. Mod. Phys. E

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Evidence for the existence of a superheavy nucleus with atomic mass number A=292 and abundance (1-10)x10 -12 relative to 232 Th has been found in a study of natural Th using inductively coupled plasma-sector field mass spectrometry. The measured mass matches the predictions 1,2 for the mass of an isotope with atomic number Z=122 or a nearby element. Its estimated half-life of t 1/2 ≥10 8 y suggests that a long-lived isomeric state exists in this isotope. The possibility that it might belong to a new class of long-lived high spin super-and hyperdeformed isomeric states is discussed. 3-6The question "how heavy can a nucleus be" is a fundamental problem in nuclear physics. The mass M A of an atom is equal to:where M H and M n are the masses of the hydrogen atom and the neutron, respectively, and BE is the binding energy of the nucleus. The binding energy per nucleon (BE/u) of stable nuclei has a broad maximum around A ≈ 60, with a value of 8.7 MeV/u, which falls monotonically to about 7.6 MeV/u at Th and U. 19 The predicted BE/u values for the superactinide nuclei are around 6.9 MeV/u. 1,2,20,21 Therefore, masses of superactinide isotopes are higher than, and resolvable from, the masses of all molecules with the same mass number, except for multihydrogen-containing molecules. This is seen in Fig. 1 In principle, natural minerals like monazite, which is the usual source material for Th, would be the most promising materials to study. However, background was the main obstacle when looking for isotopes with relative abundance of (1-10)x10 -11 in natural materials. 10Therefore, purified natural Th was used in our measurements.In the present work, we performed accurate mass measurements for masses 287 to 294 in Th solutions. Evidence was obtained for the existence of an isotope with a mass that matches the predictions for atomic mass number 292 and Z around 122. Here we describe this observation.The experimental procedure was similar to that described earlier. 10 Inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) was used for the experiments. The ICP-SFMS is an Element2 (Finnigan, Thermo-Electron, Bremen, Germany). In this instrument, a solution of the material to be studied is introduced into a high temperature (6000-8000 K) plasma source. At these temperatures, predominantly atomic species are present. Molecular ions are produced after the source, mainly by interaction with oxygen and hydrogen ions from the solution. The predefined medium resolution mode, m/∆m = 4000 (10% valley definition), was used throughout to separate atomic ions from molecules with the same mass number. The sensitivity-enhanced set-up of the instrument was similar to that described in Ref. During the first session, masses from 287 to 294 were analysed using the Th solutions with an integration time of 1 s channel -1 , and these measurements were made three to five times each. In one spectrum, two events were observed with a solution produced by CustomerGrade (from LGC Promochem AB, Borås, Sweden) at a mass that fits the predic...

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“…In this regard, the fission reaction channel offers excellent possibilities. For example, sharp transmission resonances were observed in the fission reaction 235 U(d,pf ) 236 U and interpreted as being hyperdeformed rotational bands lying in the third well of the fission barrier [1].…”

Section: Introductionmentioning

confidence: 99%

Role of transitional levels inNp237(γ,f): Perspectives for studying highly deformed systems

Arruda‐Neto¹,

Mesa²,

Garcı́a³

et al. 2006

Phys. Rev. C

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The transition levels at the top of the two 237 Np fission barriers were obtained for the first time by means of the so-called semimicroscopic combined method, which we have developed and implemented. To overcome the difficulties in dealing with large nuclear deformations, we used our developed BARRIER code, which calculates single-particle spectra in a deformed Woods-Saxon potential using a coordinate system based on Cassini ovaloids as nuclear shape parametrization. The results enabled us to describe the experimentally observed near-barrier photofission cross-section structures for 237 Np, as well as a subbarrier shelf, the latter being consistently interpreted in terms of the accumulation of levels at the top of the inner and outer double fission barrier of 237 Np.

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Experimental Evidence for Hyperdeformed States in U Isotopes

Cited by 85 publications

References 28 publications

Multiple-humped fission and fusion barriers of actinide and superheavy elements

Multiple-humped fission and fusion barriers of actinide and superheavy elements

EVIDENCE FOR THE POSSIBLE EXISTENCE OF A LONG-LIVED SUPERHEAVY NUCLEUS WITH ATOMIC MASS NUMBER A = 292 AND ATOMIC NUMBER Z ≅ 122 IN NATURAL Th

Role of transitional levels inNp237(γ,f): Perspectives for studying highly deformed systems

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