New nuclear structure features in transactinide nuclei

Bucurescu, D.; Zamfir, N. V.

doi:10.1103/physrevc.87.054324

Cited by 20 publications

(34 citation statements)

References 14 publications

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“…Alpha-decay is a prominent decay channel of heavy and superheavy nuclei (SHN) and acts as an effective probe for the nuclear structure [1][2][3][4][5][6][7][8][9][10][11]. α-decay can provide a powerful and very precise tool to identify new superheavy elements studied at accelerator centers such as Berkeley, GSI, Dubna, GANIL, and RIKEN [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Alpha-decay of deformed superheavy nuclei as a probe of shell closures

et al. 2017

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Section: Introductionmentioning

confidence: 99%

Alpha-decay of deformed superheavy nuclei as a probe of shell closures

et al. 2017

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“…An extension of such studies to other (strongly radioactive) targets of interest in the region discussed here is undoubtedly a very difficult task, leaving the alpha decay as the main spectroscopic tool for these nuclei. An examination of the HFs known for parent nuclei with Z 82 was recently presented by us [10]. Most of the nuclei in our set, i.e., those with mass number larger than about 220, present collective features.…”

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confidence: 99%

“…In Ref. [10] it was argued that these VCS representations should be useful for the HF values because these are quantities that depend only on the nuclear structure. Indeed, it was found that the VCS representations display much more compact trajectories for the HF values, than, e.g., the usual representation as a function of the mass number A [10].…”

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confidence: 99%

“…[10] it was argued that these VCS representations should be useful for the HF values because these are quantities that depend only on the nuclear structure. Indeed, it was found that the VCS representations display much more compact trajectories for the HF values, than, e.g., the usual representation as a function of the mass number A [10]. The advantages of the VCS representations are (i) compact patterns with small scattering of the data points, that can be used to predict HF values in nuclei where these are not measured; (ii) removal of the isobaric ambiguities (in our set of nuclei there are a number of doublets, or even triplets of nuclei having the same mass); (iii) the evolution as a function of P is easily related to that of the collectivity.…”

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confidence: 99%

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Fine structure inαdecay of even-even trans-lead nuclei: An insufficiently exploited spectroscopic tool

Bucurescu

Zamfir

2012

Phys. Rev. C

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The experimental values of both branching ratios and hindrance factors for the alpha decay of even-even trans-lead nuclei, corresponding to the 2 + 1 , 4 + 1 , and 6 + 1 excited states in the daughter nucleus, are examined within the valence correlation scheme. Existing calculations do not reproduce certain conspicuous features of these data in the deformed nuclei region, thus leaving open the question of what details of nuclear structure in this region are responsible for these effects.Although it is one of the oldest observed nuclear structure phenomena, alpha decay remains a very important experimental tool for the investigation of unstable nuclei, especially the superheavy ones. The fine structure of the alpha decay was experimentally observed by Salomon Rosenblum in 1929 [1], and, soon after that, explained by Gamow [2] as due to the population of the ground and excited states in the daughter nucleus.The population of the excited states in the residual nucleus is usually much weaker than that of the ground state, mainly due to the different Q values, reflecting the strong energy dependence of the penetrability of the alpha particle through the nuclear and Coulomb potential barrier. On the other hand, the population intensity of the excited states also contains important information on their structure. However, the theoretical calculation of the absolute values of the alpha-decay rates is a problem that is not fully solved yet. The best studied alphadecay processes are those implying the unhindered transitions (with L = 0), that have mostly been measured for the ground state to ground state transition of even-even nuclei, whereas the population of the excited states in the daughter nuclei (the fine structure of α decay), especially for nonzero spin states, has been much less studied. In this work we show that the experimental fine structure data for the yrast 2 + , 4 + , and 6 + states in even-even trans-lead daughter nuclei are not fully understood by the current theoretical models of alpha decay, implying that certain details of the structure of these states are neglected, or even not understood. To this end, we review the systematics of the experimental data [3-5] on the α-decay fine structure measured for the even-even trans-lead nuclei.The quantities experimentally determined in alpha decay are the Q values (related to the excitation energies of the daughter nucleus states), the branching ratios B r,i (for excited states denoted by i), and the half-life T 1/2 of the alpha-decaying state in the parent nucleus (in our case, the 0 + ground state). For each state i one defines a partial half-life T 1/2,i = T 1/2 /B r,i and a partial width i =h ln 2/T 1/2,i . One usually factorizes the widths as i = δ 2 i P i where δ 2 is called reduced width [6] and mainly contains the nuclear structure information, while * bucurescu@tandem.nipne.ro † zamfir@tandem.nipne.ro P is the penetrability of the alpha particle through the barrier. For comparison with theory one also defines the hindrance factors (HFs) asThus, for the...

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“…Theoretical studies with increasing particle numbers investigate the so-called "island of stability" [6], where features like the continuing decrease of energy gaps [7] and the emergence of shape coexistence [8] have a crucial impact on the predicted position and localization of stability regions and the corresponding lifetimes of the nuclei. Although the first experimental evidence for SHN has reached the region of the predicted subshell closure at N ¼ 162 [9-11], the deformed shell closure at N ¼ 152 for transfermium nuclei (see, e.g., [12]) and, as recently pointed out, weaker shell effects in the vicinity [13], still represents the cutting edge for thorough experimental investigations. The transfermium nuclei, however, can be produced only online, in heavy-ion fusion and nucleon transfer reactions, and consequently only low yields are available for study, necessitating highly efficient techniques.…”

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confidence: 99%

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph

Ito¹,

Schury²,

Wada³

et al. 2018

Phys. Rev. Lett.

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The masses of 246 Es, 251 Fm, and the transfermium nuclei 249−252 Md and 254 No, produced by hot-and cold-fusion reactions, in the vicinity of the deformed N ¼ 152 neutron shell closure, have been directly measured using a multireflection time-of-flight mass spectrograph. Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter δ 2n derived from three isotopic masses was updated with the new masses and corroborates the existence of the deformed N ¼ 152 neutron shell closure for Md and Lr. DOI: 10.1103/PhysRevLett.120.152501 Precision mass measurements of unstable nuclei, providing a direct measure of the nuclear binding energy, are invaluable for the study of nuclear shell evolution and collective effects, such as deformations, far from stability [1,2]. For transfermium nuclei and the yet poorly investigated region towards the superheavy nuclei (SHN), where proton repulsion becomes a generally dominant feature, the description of nuclear lifetimes depends crucially on shell stabilization effects mainly driven by deformed shells [3][4][5]. Theoretical studies with increasing particle numbers investigate the so-called "island of stability" [6], where features like the continuing decrease of energy gaps [7] and the emergence of shape coexistence [8] have a crucial impact on the predicted position and localization of stability regions and the corresponding lifetimes of the nuclei. Although the first experimental evidence for SHN has reached the region of the predicted subshell closure at N ¼ 162 [9-11], the deformed shell closure at N ¼ 152 for transfermium nuclei (see, e.g., [12]) and, as recently pointed out, weaker shell effects in the vicinity [13], still represents the cutting edge for thorough experimental investigations. The transfermium nuclei, however, can be produced only online, in heavy-ion fusion and nucleon transfer reactions, and consequently only low yields are available for study, necessitating highly efficient techniques. Direct mass measurements of transfermium nuclei have so far been performed for only six nuclei-four isotopes of nobelium and two isotopes of lawrencium-with the Penning trap mass spectrometer SHIPTRAP [14,15].In this Letter, we report the first implementation of a multireflection time-of-flight mass spectrograph (MRTOF MS) for transfermium nuclei as shown in Fig. 1, including new mass measurements of 246 Es, 251 Fm, [249][250][251][252]

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New nuclear structure features in transactinide nuclei

Cited by 20 publications

References 14 publications

Alpha-decay of deformed superheavy nuclei as a probe of shell closures

Alpha-decay of deformed superheavy nuclei as a probe of shell closures

Fine structure inαdecay of even-even trans-lead nuclei: An insufficiently exploited spectroscopic tool

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph

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