Author: webref

R. Rodriguez-Guzman, L.M. Robledo

Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in the isotopes 250−260No. The even-even isotopes have been considered within the standard Hartree-Fock-Bogoliobov (HFB) framework while for the odd-mass ones the Equal Filling Approximation (HFB-EFA) has been employed. Ground state quantum numbers and deformations, pairing energies, one-neutron separation energies, inner and outer barrier heights as well as fission isomer excitation energies are given. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the systematic of the spontaneous fission half-lives tSF both for even-even and odd-mass nuclei. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation, it is shown that both the specialization energy and the pairing quenching effects, taken into account within the self-consistent HFB-EFA blocking procedure, lead to larger tSF values in odd-mass nuclei as compared with their even-even neighbors. Alpha decay lifetimes have also been computed using a parametrization of the Viola-Seaborg formula. The high quality of the Gogny-D1M functional regarding nuclear masses leads to a very good reproduction of Qα values and consequently of lifetimes.

Alejandro J. Garza, Ana G. Sousa Alencar, Gustavo E. Scuseria

Singlet-paired coupled cluster doubles (CCD0) is a simplification of CCD that relinquishes a fraction of dynamic correlation in order to be able to describe static correlation. Combinations of CCD0 with density functionals that recover specifically the dynamic correlation missing in the former have also been developed recently. Here, we assess the accuracy of CCD0 and CCD0+DFT (and variants of these using Brueckner orbitals) as compared to well-established quantum chemical methods for describing ground-state properties of singlet actinide molecules. The f0 actinyl series (UO2+2, NpO2+2, PuO2+2), the isoelectronic NUN, and Thorium (ThO, ThO2+) and Nobelium (NoO, NoO2) oxides are studied.

Yang Sun, Gui-Lu Long, Falih Al-Khudair, and Javid A. Sheikh

Recent experimental advances have made it possible to study excited structure in superheavy nuclei. The observed states have often been interpreted as quasiparticle excitations. We show that in superheavy nuclei collective vibrations systematically appear as low-energy excitation modes. By using the microscopic Triaxial Projected Shell Model, we make a detailed prediction on γ-vibrational states and their $E2$ transition probabilities to the ground state band in fermium and nobelium isotopes where active structure research is going on, and in $270\mathrm{Ds}$, the heaviest isotope where decay data have been obtained for the ground-state and for an isomeric state.

Yue Shi, J. Dobaczewski, P.T. Greenlees

Nuclei in the Z≈100 mass region represent the heaviest systems where detailed spectroscopic information is experimentally available. Although microscopic-macroscopic and self-consistent models have achieved great success in describing the data in this mass region, a fully satisfying precise theoretical description is still missing.
By using fine-tuned parametrizations of the energy density functionals, the present work aims at an improved description of the single-particle properties and rotational bands in the nobelium region. Such locally optimized parameterizations may have better properties when extrapolating towards the superheavy region.
Skyrme-Hartree-Fock-Bogolyubov and Lipkin-Nogami methods were used to calculate the quasiparticle energies and rotational bands of nuclei in the nobelium region. Starting from the most recent Skyrme parametrization, UNEDF1, the spin-orbit coupling constants and pairing strengths have been tuned, so as to achieve a better agreement with the excitation spectra and odd-even mass differences in 251Cf and 249Bk.
The quasiparticle properties of 251Cf and 249Bk were very well reproduced. At the same time, crucial deformed neutron and proton shell gaps open up at N=152 and Z=100, respectively. Rotational bands in Fm, No, and Rf isotopes, where experimental data are available, were also fairly well described. To help future improvements towards a more precise description, small deficiencies of the approach were carefully identified.
In the Z≈100 mass region, larger spin-orbit strengths than those from global adjustments lead to improved agreement with data. Puzzling effects of particle-number restoration on the calculated moment of inertia, at odds with the experimental behaviour, require further scrutiny.

Yue Shi, J. Dobaczewski, P.T. Greenlees, J. Toivanen, P. Toivanen

We have performed self-consistent Skyrme Hartree-Fock-Bogolyubov calculations for nuclei close to 254No. Self-consistent deformations, including β2,4,6,8 as functions of the rotational frequency, were determined for even-even nuclei 246,248,250Fm, 252,254No, and 256Rf. The quasiparticle spectra for N=151 isotones and Z=99 isotopes were calculated and compared with experimental data and the results of Woods-Saxon calculations. We found that our calculations give high-order deformations similar to those obtained for the Woods-Saxon potential, and that the experimental quasiparticle energies are reasonably well reproduced.

M. Bender, P. Bonche, T. Duguet, P.-H. Heenen

Self-consistent mean field calculations with the SLy4 interaction and a density-dependent pairing force are presented for nuclei in the Nobelium mass region. Predicted quasi-particle spectra are compared with experiment for the heaviest known odd N and odd Z nuclei. Spectra and rotational bands are presented for nuclei around No252,4 for which experiments are either planned or already running.

J. Dobaczewski, A.V. Afanasjev, M. Bender, L.M. Robledo, Yue Shi

We calculate properties of the ground and excited states of nuclei in the nobelium region for proton and neutron numbers of 92 <= Z <= 104 and 144 <= N <= 156, respectively. We use three different energy-density-functional (EDF) approaches, based on covariant, Skyrme, and Gogny functionals, each within two different parameter sets. A comparative analysis of the results obtained for odd-even mass staggerings, quasiparticle spectra, and moments of inertia allows us to identify single-particle and shell effects that are characteristic to these different models and to illustrate possible systematic uncertainties related to using the EDF modelling

E. Minaya Ramirez, D. Ackermann, K. Blaum, M. Block, C. Droese, Ch. E. Düllmann, M. Dworschak, M. Eibach, S. Eliseev, E. Haettner, F. Herfurth, F.P. Heßberger, S. Hofmann, J. Ketelaer, G. Marx, M. Mazzocco, D. Nesterenko, Yu.N. Novikov, W.R. Plaß, D. Rodríguez, C. Scheidenberger, L. Schweikhard, P.G. Thirolf, C. Weber

Quantum-mechanical shell effects are expected to strongly enhance nuclear binding on an “island of stability” of superheavy elements. The predicted center at proton number Z=114,120, or 126 and neutron number N=184 has been substantiated by the recent synthesis of new elements up to Z=118. However the location of the center and the extension of the island of stability remain vague. High-precision mass spectrometry allows the direct measurement of nuclear binding energies and thus the determination of the strength of shell effects. Here, we present such measurements for nobelium and lawrencium isotopes, which also pin down the deformed shell gap at N=152.

I.V. Toranzo a c, P. Sánchez-Moreno b c, R.O. Esquivel c d, J.S. Dehesa a c

Ossama Kullie

In this work we present a four component relativistic theoretical investigation of the trihalides of lutetium and lawrencium, LuX3, LrX3 (X= F, Cl, Br, I) respectively using density functional theory (DFT) with different density functional and a geometrical optimisation procedure as implemented in DIRAC-package. The results show the trend of bonding from lighter to the heavier halide atoms and between 4f/5f atoms Lu and Lr.

Lawrencium is a chemical element with the symbol Lr and atomic number 103. It is a synthetic element and belongs to the actinide series of elements in the periodic table. Lawrencium is a highly radioactive metal that is not found naturally on Earth in significant amounts.

Key Characteristics of Lawrencium:

1. Radioactivity: Lawrencium is an extremely radioactive element, and all of its isotopes are unstable. Its most stable isotope, lawrencium-262, has a relatively short half-life of about 3.6 hours. Lawrencium emits alpha particles, beta particles, and gamma radiation during its radioactive decay.
2. Occurrence: Lawrencium is not found naturally on Earth. It is a synthetic element produced in nuclear reactors or through neutron bombardment of other elements, such as californium.
3. Chemical Properties: Lawrencium is a reactive element and readily forms compounds with oxygen, halogens, and other elements. It exhibits various oxidation states, with the +3 state being the most common. Due to its high radioactivity, lawrencium is challenging to handle and study.
4. Applications: Due to its extreme radioactivity and limited availability, lawrencium has very few practical applications. It is primarily used for scientific research purposes, particularly in the study of nuclear reactions and the behavior of heavy elements.
5. Biological Role: Lawrencium is highly radioactive and poses a significant health hazard. It has no known biological role and is toxic to living organisms.

Lawrencium’s synthetic nature, high radioactivity, and limited availability make it primarily of interest to researchers in nuclear science for fundamental studies. Its use is mainly focused on advancing our understanding of nuclear reactions and the behavior of heavy elements. Due to its extreme radioactivity, lawrencium requires strict handling protocols and safety precautions.

Nobelium is a chemical element with the symbol No and atomic number 102. It is a synthetic element and belongs to the actinide series of elements in the periodic table. Nobelium is a highly radioactive metal that is not found naturally on Earth in significant amounts.

Key Characteristics of Nobelium:

1. Radioactivity: Nobelium is an extremely radioactive element, and all of its isotopes are unstable. Its most stable isotope, nobelium-259, has a relatively short half-life of about 58 minutes. Nobelium emits alpha particles, beta particles, and gamma radiation during its radioactive decay.
2. Occurrence: Nobelium is not found naturally on Earth. It is a synthetic element produced in nuclear reactors or through neutron bombardment of other elements, such as curium.
3. Chemical Properties: Nobelium is a reactive element and readily forms compounds with oxygen, halogens, and other elements. It exhibits various oxidation states, with the +2, +3, and +4 states being the most common. Due to its high radioactivity, nobelium is challenging to handle and study.
4. Applications: Due to its extreme radioactivity and limited availability, nobelium has very few practical applications. It is primarily used for scientific research purposes, particularly in the study of nuclear reactions and the behavior of heavy elements.
5. Biological Role: Nobelium is highly radioactive and poses a significant health hazard. It has no known biological role and is toxic to living organisms.

Nobelium’s synthetic nature, high radioactivity, and limited availability make it primarily of interest to researchers in nuclear science for fundamental studies. Its use is mainly focused on advancing our understanding of nuclear reactions and the behavior of heavy elements. Due to its extreme radioactivity, nobelium requires strict handling protocols and safety precautions.