Effect Of Nuclear Deformation Research Articles

Effect of nuclear deformation and orientation about the symmetry axis of the target nucleus on heavy-ion fusion dynamics

Effect of nuclear deformation and orientation about the symmetry axis of the target nucleus on heavy-ion fusion dynamics

Nuclear deformation effects in the spectra of highly charged ions

With the increasing precision of spectroscopic measurements, there is a growing demand for more accurate theoretical predictions, which requires the estimation of various higher-order effects, such as the nuclear deformation effect. Here, we present the results for nuclear deformation correction for the widest range of nuclei. The effects are investigated in terms of electronic transition energies, g factors, and hyperfine splitting constants, by implementing the deformed Fermi nuclear model to the Dirac equation. Based on the improved methodology and appropriate data classification, we present the results for over 1100 nuclei on figures, showing the general trends and anomalies. Moreover, it can serve as a simple tool providing estimations for specific planned research. In addition, we examine the connections and significance of deformation effects in the search of new physics with singly charged ions. Published by the American Physical Society 2024

Nuclear structure properties and weak interaction rates of even–even Fe isotopes

Nuclear structure properties and weak interaction rates of neutron-rich even–even iron (Fe) isotopes (A = 50 – 70) are investigated using the Interacting Boson Model-1 (IBM-1) and the proton–neutron Quasiparticle Random Phase Approximation (pn-QRPA) model. The IBM-1 is used for the calculation of energy levels and the B(E2) values of neutron-rich Fe isotopes. Later their geometry was predicted within the potential energy formalism of the IBM-1 model. Weak interaction rates on neutron-rich nuclei are needed for the modeling and simulation of presupernova evolution of massive stars. In the current study, we investigate the possible effect of nuclear deformation on stellar rates of even–even Fe isotopes. The pn-QRPA model is applied to calculate the weak interaction rates of selected Fe isotopes using three different values of deformation parameter. It is noted that, in general, bigger deformation values led to smaller total strength and larger centroid values of the resulting Gamow–Teller distributions. This later translated to smaller computed weak interaction rates. The current finding warrants further investigation before it may be generalized. The reported stellar rates are up to 4 orders of magnitude smaller than previous calculations and may bear astrophysical significance.

Abstract 5641: Transcriptional regulation by nuclear deformation

Abstract Establishment and maintenance of cell identities requires transcriptional rewiring and modulation of three-dimensional genome organization. The nucleus is subject to constant mechanical forces, both intrinsic from the cytoskeleton and extrinsic, such as compression, confinement, and stretch. Recently, work from us and others implicate mechanical force, through activating biochemical signaling pathways as well as direct nuclear deformation, in remodeling nuclear architecture, chromatin state and global gene expression patterns. Thus, we hypothesize that mechanical force plays an important role in coordinating and thresholding transcriptional responses. Here, we challenge this hypothesis by quantifying the effect of nuclear deformation on transcription in real time at single cell resolution quasi genome wide. Further, recent work elucidated that the MYC oncogene exerts global effects on transcriptional output by altering the binding dynamics of transcription factors involved in the activation and productive elongation of RNA Polymerase II. This contrasts with mechanical stress which reduces global levels of RNA Polymerase II. Here we interrogate how transcriptional output is tuned for specific genetic programs/loci by mechanical force using MYC as a paradigm. Citation Format: Andrew Cook, Rebecca Stephens, Nadezda Fursova, Carson C. Chow, Dan Larson, Yekaterina Miroshnikova. Transcriptional regulation by nuclear deformation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5641.

Deformation dependence of thermal properties of hot rotating 184Re with inclusion of nuclear pairing fluctuations

In this work, the effects of nuclear deformation and angular momentum on the thermodynamic properties of 184Re have been investigated. In this regard, we have used the mean gap BCS (MEGBCS) model to consider thermal fluctuations. In this model, thermodynamic quantities are calculated using the mean gap parameter at various angular momenta. The results show that the pairing gap increases with increasing temperature at high angular momentum, known as thermally assisted pairing correlation. Also, the S-shaped heat capacity, interpreted as pairing phase transition, washes out with increasing angular momentum and nuclear deformation. We also calculated the nuclear level density versus excitation energy at various nuclear deformations and angular momenta. Compared with experimental data at J=(12±4)ħ, our results show that the shape of the nucleus changes as the excitation energy increases at J=12ħ. Also, our calculations on level density indicate that with increasing excitation energy at β2=0.23, the nuclear angular momentum increases from J=8ħ to J=16ħ.

Re-examination of β-decay in Hg, Pb and Po Isotopes

This study re-examines the effect of nuclear deformation on the calculated Gamow-Teller (GT) strength distributions of neutron-deficient (178−192Hg, 185−194Pb and 196−206Po) nuclei. The nuclear ground state properties and shape parameters were calculated using the Relativistic Mean Field model. Three different density-dependent interactions (D3C, DD-ME2 and DD-PC1) were used in the calculation. Estimated shape parameters were later used within the framework of deformed proton-neutron quasi-random phase approximations model, with a separable interaction, to calculate the GT strength distributions, half-lives and branching ratios for these neutron–deficient isotopes. It was concluded that half-lives and GT strength distributions vary considerably with change in shape parameter.

Momentum-dependent flow correlations in deformed nuclei at collision energies available at the BNL Relativistic Heavy Ion Collider

Flow fluctuations in ultrarelativistic heavy-ion collisions can be probed by studying the momentum dependent correlations or the factorization-breaking coefficients between flow harmonics in separate kinematic bins (transverse momentum $p$ or pseudorapidity $\ensuremath{\eta}$). We study such factorization-breaking coefficients for collisions of deformed $^{238}\mathrm{U}+^{238}\mathrm{U}$ nuclei to see the effect of the nuclear deformation on momentum dependent coefficients. We also study momentum dependent mixed-flow correlations for the isobar collision system: $^{96}\mathrm{Ru}+^{96}\mathrm{Ru}$ and $^{96}\mathrm{Zr}+^{96}\mathrm{Zr}$, which have the same mass number but different nuclear structure, thus providing the ideal scenario to study nuclear deformation effect on such observables. We use the TRENTO $+$ MUSIC model for simulations and event-by-event analysis of those observables. We find that these momentum dependent correlation coefficients are not only excellent candidates to probe the fluctuation in heavy-ion collision, but also show significant sensitivity to the nuclear deformation.

Ab initio calculations of the 2p3/2→2s transition in He-, Li-, and Be-like uranium

The bound-state QED approach is applied to calculations of the $2p_{3/2} \rightarrow 2s$ transition energies in He-, Li-, and Be-like uranium. For U$^{90+}$ and U$^{89+}$, standard perturbation theory for a single level is employed, while the calculations of U$^{88+}$ have required its counterpart for quasidegenerate levels. The utilized approach merges the rigorous QED treatment up to the second order of perturbation theory with the higher-order electron-correlation contributions evaluated within the Breit approximation. The higher-order screened QED effects are estimated by means of the model-QED operator. The nuclear recoil, nuclear polarization, and nuclear deformation effects are taken into account as well. Along with the transition energies, their pairwise differences are calculated. The comprehensive analysis of the uncertainties due to uncalculated effects is carried out, and the most accurate theoretical predictions, which are in perfect agreement with available experimental data, are obtained.

Effect of nuclear deformation on proton bubble structure in Z = 14 isotopes

Effect of nuclear deformation on proton bubble structure in Z = 14 isotopes

Investigation of Gamow–Teller strength of 186Hg within deformed pn-QRPA

Recently, the total absorption gamma spectroscopy technique was used to determine the Gamow–Teller (GT) distribution of β-decay of 186Hg. It was concluded that the best description of the measured data was obtained with dominantly prolate components for both parent 186Hg and daughter 186Au. Motivated by the recent findings, we investigate the effect of nuclear deformation on the energy distribution of the GT strength of the decay of 186Hg into 186Au within the framework of proton–neutron quasiparticle random phase approximation (pn-QRPA) based on the deformed Nilsson potential. To do the needful, we first calculate the energy levels and shape prediction of 186Hg within the interacting boson model. The computed GT strength distribution satisfied the model-independent Ikeda sum rule 100% (99.98%) for the prolate (oblate) case. Based on the strength distributions, the deformed pn-QRPA model with separable interaction prefers a prolate shape for the ground state of 186Hg and supports the shape coexistence for this nucleus.

Exploring the effect of hadron cascade time on particle production in Xe+Xe collisions at sNN=5.44 TeV using a multiphase transport model

Heavy-ion collisions at ultrarelativistic energies provide extreme conditions of energy density and temperature to produce a deconfined state of quarks and gluons. Xenon (Xe), being a deformed nucleus, further gives access to the effect of initial geometry on final state particle production. This study focuses on the effect of nuclear deformation and hadron cascade-time on the particle production and elliptic flow using a multiphase transport (AMPT) model in $\mathrm{Xe}+\mathrm{Xe}$ collisions at $\sqrt{{s}_{NN}}=5.44\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$. We explore the effect of hadronic cascade time on identified particle production through the study of ${p}_{\mathrm{T}}$-differential particle ratios. The effect of hadronic cascade time on the generation of elliptic flow is studied by varying the cascade time between 5 and $25\phantom{\rule{0.16em}{0ex}}\mathrm{fm}/c$. This study shows the final state interactions among particles generate additional anisotropic flow with increasing hadron cascade time, especially at very low and high ${p}_{\mathrm{T}}$.

Effect of nuclear deformation on the observation of a low-energy super-Gamow-Teller state

A well-known structure with concentrated Gamow-Teller (GT) transitions is the Gamow-Teller resonance, which has been observed at higher-energy regions (usually $>6$ MeV) of nuclear excitation. It has been found that the GT strength can also concentrate in the lowest ${J}^{\ensuremath{\pi}}={1}^{+}$ GT state named the ``low-energy super-GT (LeSGT) state'' when the initial even-even nucleus has the structure of ``LS-closed-shell core nucleus $+$ 2 neutrons (or 2 protons)'' and the final nucleus ``LS-closed-shell core nucleus $+$ 1 proton and 1 neutron.'' Such concentrations are realized with the core nuclei $^{4}\mathrm{He}$, $^{16}\mathrm{O}$, and $^{40}\mathrm{Ca}$, corresponding to the shell closures of $s$, $p$, and $sd$ shells, respectively. It is natural to speculate that the LeSGT state may also be observed in the $A=82$ systems if the $N=Z=40$ shell gap is significant and $^{80}\mathrm{Zr}$ represents a good core nucleus corresponding to the $pf$ shell closure. Possible conditions that allow the formation of the LeSGT state in the $^{82}\mathrm{Zr}\ensuremath{\rightarrow}^{82}\mathrm{Nb}$ charge-exchange reaction (or $^{82}\mathrm{Mo}\ensuremath{\rightarrow}^{82}\mathrm{Nb}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$ decay) are discussed by evaluating the results of projected shell model calculations, which are based on deformed model space. Our calculations show that with increasing deformation, the LeSGT feature found in the spherical limit (zero deformation) evolves gradually into a broad distribution in the higher-energy region. This lets us conclude that no LeSGT state is expected in $^{82}\mathrm{Nb}$ because the shape of the $^{80}\mathrm{Zr}$ core nucleus is ellipsoidal.

Theoretical calculations of the nuclear deformation effects on α-decay half-lives for heavy and super-heavy nuclei

α-decay half-lives of heavy and super-heavy even–even nuclei, in the range of Z = 80–118, were studied using an improved generalized liquid drop model, in which the deformation effects of both the parent and daughter nuclei are considered. The calculated values reflect a better accuracy of the agreement when compared with the experimental data of known nuclei from Hg to Og. The corresponding standard deviation reduced to 0.3670, which proves that the employed method is reliable to reproduce the α-decay half-lives. Semi-empirical formulas like the Royer formula and the universal decay law were also used for systematic calculations of α-decay half-lives. Based on a detailed analysis of the deformation effects in heavy and super-heavy nuclear regions, it was found that the nuclear deformation has a stronger influence on the super-heavy region. The competition between α-decay and spontaneous fission (SF) was also studied and it was observed that for some isotopes from Pu to Fl, the competition between two decay modes is intense, which reflects that these nuclei may follow both decay modes. A neutron magic number, N = 184, and sub-magic numbers, N = 152 and 162 were observed after the analysis of the α-decay half-lives and the SF half-lives of unknown even–even nuclei.

Effects of nuclear deformation in U$+$U collisions at the intermediate energy

Nuclear deformation is an important topic in the study of nuclear structure. The influence of nuclear structure on nuclear reactions and heavy-ion collisions has attracted considerable attention recently. Based on the ultra-relativistic quantum molecular dynamics (UrQMD) model, the effect of nuclear deformation in $^{238}$U$+$$^{238}$U at the beam energy of łinebreak 0.4 GeV/nucleon is investigated and several observables, such as the stopping power, collective flow, and $\pi^{-}/\pi^{+}$ yield ratio, are calculated. It is found that the stopping power obtained with tip-tip (the two nuclei with their long axes head-on) collisions is the largest among collisions with different deformations. For belly-belly (the two nuclei with their short axes head-on and long axes parallel in the reaction plane) collisions, the elliptic flow exists even for the most central collision ($b$=0 fm). $\pi^{-}/\pi^{+}$yield ratio obtained with tip-tip collision is larger than that obtained with belly-belly collision. In addition, the influence of nuclear deformation on the elliptic flow of free protons is stronger than that of nuclear symmetry energy in $^{238}$U$+$$^{238}$U collisions at 0.4 GeV/nucleon, while the elliptic flow ratio between neutrons and protons shows hardly any sensitivity to different deformations of uranium.

Mechanical Stress to Cell Nucleus Inhibits Proliferation and Differentiation of Vascular Smooth Muscle Cells

Cells sense the external environment such as a surface topography and change many cellular functions. Cell nucleus has been proposed to act as a cellular mechanosensor, and the changes in nuclear shape possibly affect the functional regulation of cells. This study demonstrated a large-scale mechanical deformation of the intracellular nucleus using polydimethylsiloxane (PDMS)-based micropillar substrates and investigated the effects of nuclear deformation on migration, proliferation, and differentiation of vascular smooth muscle cells (VSMCs). VSMCs spread completely between the fibronectin-coated pillars, leading to strong deformations of their nuclei resulted in a significant inhibition of the cell migration. The proliferation and smooth muscle differentiation of VSMCs with deformed nuclei were dramatically inhibited on the micropillars. These results indicate that the inhibition of proliferation and VSMC differentiation resulted from deformation of the nucleus with high internal stress, and this type of large-scale nuclear mechanical stress might lead the cells to a “quiescent state”.

Nuclear Deformation Effects to the Formation Cross Section of $\eta '$ Mesic Nucleus

Nuclear Deformation Effects to the Formation Cross Section of $\eta '$ Mesic Nucleus

Effect of nuclear deformation on electron capture cross-section on chromium isotopes

The electron capture plays significant role in the presupernova and supernova evolutions of massive stars which in turn are of great importance in synthesizing heavy elements beyond iron. In this paper, we study the effect of nuclear deformation on the computed electron capture cross-section on selected even–even chromium isotopes ([Formula: see text]Cr). The nuclear deformation parameters were computed using two different theoretical models: Interacting Boson Model (IBM-1) and Macroscopic (Yukawa-plus-exponential)–microscopic (Folded–Yukawa) model (Mac–mic model). A third value of deformation parameter was adopted from experimental data. We chose the pn-QRPA model to perform our calculations. The predictive power of the chosen model was first tested by calculating Gamow–Teller (GT) strength distributions of selected [Formula: see text]-shell nuclei where measured GT data was available. The calculated GT strength distributions were well-fragmented over the energy range 0–12[Formula: see text]MeV and were noted to be in decent agreement with experimental data. The total GT strength was found to increase (decrease) with decrease (increase) in the value of deformation parameter for the three chromium isotopes. The computed GT strength distributions satisfied the model-independent Ikeda sum rule. The ECC were calculated as a function of the deformation parameter at core temperature 1.0[Formula: see text]MeV. Our results show that the calculated ECC increased with increasing value of nuclear deformation.

Nuclear Mechanics and Cancer Cell Migration.

As a cancer cell invades adjacent tissue, penetrates a basement membrane barrier, or squeezes into a blood capillary, its nucleus can be greatly constricted. Here, we examine: (1) the passive and active deformation of the nucleus during 3D migration; (2) the nuclear structures-namely, the lamina and chromatin-that govern nuclear deformability; (3) the effect of large nuclear deformation on DNA and nuclear factors; and (4) the downstream consequences of mechanically stressing the nucleus. We focus especially on recent studies showing that constricted migration causes nuclear envelope rupture and excess DNA damage, leading to cell cycle suppression, possibly cell death, and ultimately it seems to heritable genomic variation. We first review the latest understanding of nuclear dynamics during cell migration, and then explore the functional effects of nuclear deformation, especially in relation to genome integrity and potentially cancerous mutations.

Influence of sticking vs non-sticking limits of moment of inertia and higher order deformations in the decay of 214,216Rn⁎ compound systems

The dynamical cluster decay model (DCM) is employed to explore the relative effect of sticking (IS) and non-sticking (INS) limits of moment of inertia (MOI) in the decay of hot and rotating 214,216Rn⁎ compound nuclei, formed in 16,18O + 198Pt reactions. Beside this, the nuclear deformation effects i.e. quadrupole β2 (static and dynamic) and higher order static deformations up to hexadecapole (β4) are duly incorporated and studied within DCM. The influence of both ‘INS/IS’ addressing rotational energy component and ‘deformations’ is gauged through the barrier characteristics, preformation factor and barrier lowering effects. The experimentally given ER and ff data is addressed by optimizing the neck-length ΔR, that strongly depends on the limiting angular momentum, which in turn depends on the sticking or non-sticking limits of interaction. In addition to this, the influence of increase in energy and neutron number is probed in reference to ER survival probability of Rn compound nucleus. Finally, the ff cross-sections of 214,216Rn⁎ nuclei are predicted within sticking limit of moment of inertia as the same seems to be more suitable for such decay paths.

Relationship between and effect of inelastic excitations and transfer channels on sub-barrier fusion enhancement

Background: It is a well established fact that nuclear deformation and vibration influence fusion dynamics around the Coulomb barrier. This effect was observed for several systems with the inclusion of inelastic excitations in coupled-channels calculations. Sub-barrier fusion cross sections were also observed to be affected by neutron transfer in systems carrying positive $Q$ value for transfer channels. However, recent experimental analysis with a few systems showed that inelastic excitations are enough to explain the sub-barrier fusion behavior, and no effect was noticed due to positive $Q$-value transfer channels.Purpose: The motivation behind present investigation is to explore the effects of colliding nuclei structure and the transfer channel on enhancement of sub-barrier fusion cross sections.Method: An experiment was performed with Heavy Ion Reaction Analyzer (HIRA) at New Delhi to measure the fusion cross sections for $^{28}\mathrm{Si}+^{92,96}\mathrm{Zr}$ systems. These cross sections were later compared with quantum mechanical coupled-channels calculations. In order to explore the effects of nuclear deformation on fusion cross sections, the present data were compared with those of other researchers on fusion who have used various projectiles of different structural properties on a $^{96}\mathrm{Zr}$ target.Results: Experimental fusion cross sections have been extracted around the Coulomb barrier. In the coupled-channels framework, inclusion of inelastic excitations of both projectile $(^{28}\mathrm{Si})$ and targets $(^{92,96}\mathrm{Zr})$ could reproduce the experimental cross sections around the Coulomb barrier, but they deviated substantially in the sub-barrier region. This indicates that positive $Q$-value neutron transfer channels may need to be included in the calculations to reproduce the experimental cross sections at sub-barrier energies.Conclusions: The nuclear structure of interacting nuclei has a strong influence on sub-barrier fusion enhancement. The effect of multineutron transfer channels was observed to be significant for fusion, especially for those systems where interacting nuclei are less deformed or spherical.