arXiv subjects

A. Dumitrescu

Publications and source records attributed to A. Dumitrescu.

5 recordsLinked to original sources

arXiv2026

Self-consistent description of emission processes in axially-symmetric nuclei

We present a theory of cluster emission processes in terms of proton ($π$) and neutron ($ν$) single--particle (sp) degrees of freedom within a self--consistent mean--field (SCMF) constructed from a two--particle interaction having relative (rel) and center of mass (com) terms centered on the nucler surface, the latter describing the interaction between the com of a pair of particles and the surface of an axially--symmetric nucleus. In this way the $α$-clustering phenomenon becomes enhanced on the nuclear surface. We present applications for unstable nuclei that decay through the emission of $α$--particles above $^{100}\textrm{Sn}$, $^{208}\textrm{Pb}$ and within the actinidies series.

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arXiv2026

A research roadmap for assessing the feasibility of warming Mars

This roadmap outlines research pathways to determine whether Mars could be warmed with non-biological methods. It does not presuppose that warming Mars is desirable; its purpose is to identify what would need to be true for Mars to be warmed, what it would cost, and what could go wrong. Three complementary research tracks appear promising. Solid-state greenhouse membranes offer local warming, aiding water harvesting, food production, and oxygen supply near human bases. Orbiting reflectors can warm key sites such as bases and CO$_2$-ice reservoirs, although a large combined area would be required. Strengthening Mars' natural greenhouse effect might warm large regions or the globe, although many aspects remain to be worked out. Each approach carries scientific and technical risks that research must address. Near-term priorities are on-Earth testing of key parameters that will determine whether engineered aerosol warming is realistically possible, assessing whether exponential production of bioplastic habitats is possible, and designing at-Mars process experiments. In the near term, the research proposed here is closely aligned with and supports research needed to understand Mars' atmosphere and volatile evolution and hazards to human explorers. The main external uncertainty is whether or not launch costs continue to fall. This is early-stage research, and we discuss key near-term decision points, alternative pathways, and payoffs if research outcomes are negative. We also outline build-out pathways if research succeeds and demand exists. Relatively modest research investments would keep open the option of extending life beyond Earth as Mars' scientific exploration continues.

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arXiv2025

Emission processes in a self-consistent field

We present a microscopic description of cluster emission processes within the Cluster--Hartree--Fock (CHF) self--consistent field (SCF) theory. The starting point is a Woods--Saxon (WS) mean field (MF) with spin--orbit and Coulomb terms. Pairing is treated through standard Bardeen--Cooper--Schrieffer (BCS) quasiparticles. The residual two--body interaction is given by a density--dependent Wigner force having a Gaussian shape with a center of mass (com) correction located in a region of low nuclear density slightly beyond the geometrical contact radius of a system comprised from a nucleus and a surface cluster. We show that such a description adequately reproduces the ground state (gs) shape of a spherical nucleus while the surface correction enhances the radial tail of single particle orbitals, thus allowing for an adequate description of the $α$-decay width for unstable systems.

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arXiv2022

Cluster mean field description of alpha emission

We show that the Hartree-Fock-Bogoliubov (HFB) method is able to describe experimental values of alpha decay widths by including a residual nucleon-nucleon Surface Gaussian Interaction (SGI) within the standard procedure used to calculate the nuclear mean field. We call this method the Cluster HFB (CHFB) approach. In this way we correct the deficient asymptotic behaviour of the corresponding single-particle (sp) wave functions generated by the standard mean field. The corrected mean field becomes a sum between the standard mean Woods-Saxon-like field and a cluster Gaussian component centered at the same radius as the SGI. Thus, we give a confirmation of the mean field plus cluster potential structure, which was assumed in our previous work on alpha-decay widths. Systematic calculations evidence the linear correlation between the SGI strength and fragmentation potential, allowing for reliable predictions concerning the half lives of superheavy emitters.

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arXiv2016

Description of electromagnetic and favored $α$-transitions in heavy odd-mass nuclei

We describe electromagnetic and favored α-transitions to rotational bands in odd-mass nuclei built upon a single particle state with angular momentum projection $Ω=\frac{1}{2}$ in the region $88 \le Z \le 98$. We use the particle coupled to an even-even core approach described by the Coherent State Model (CSM) and the coupled channels method to estimate partial $α$-decay widths. We reproduce the energy levels of the rotational band where favored $α$-transitions occur for 26 nuclei and predict B (E2) values for electromagnetic transitions to the bandhead using a deformation parameter and a Hamiltonian strength parameter for each nucleus, together with an effective collective charge depending linearly on the deformation parameter. Where experimental data is available, the contribution of the single particle effective charge to the total B (E2) value is calculated. The Hamiltonian describing the $α$- nucleus interaction contains two terms, a spherically symmetric potential given by the double-folding of the M3Y nucleon-nucleon interaction plus a repulsive core simulating the Pauli principle and a quadrupole-quadrupole (QQ) interaction. The $α$-decaying state is identified as a narrow outgoing resonance in this potential. The intensity of the transition to the first excited state is reproduced by the QQ coupling strength. It depends linearly both on the nuclear deformation and the square of the reduced width for the decay to the bandhead, respectively. Predicted intensities for transitions to higher excited states are in a reasonable agreement with experimental data. This formalism offers a unified description of energy levels, electromagnetic and favored $α$-transitions for known heavy odd-mass $α$-emitters.

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