Light Clusters Research Articles

Study of cluster emissions from heavy nuclei using an empirical formula and the Coulomb and Proximity potential model for deformed nuclei

The decay characteristics of various clusters and neutron halo nuclei from heavy elements [Formula: see text] are studied within the framework of the Coulomb and Proximity Potential Model for Deformed Nuclei (CPPMDN) and using a new empirical formula proposed by us. The predictive power of our formula is verified by comparing the predictions with the available experimental data and with the predictions of other models such as CPPM, Universal Decay Law of Qi et al. (UDL), Unified Description formula (UD) of Ni et al. Using the present formula and CPPMDN, decay half-lives of various light clusters from heavy elements are calculated, and the results are compared with the predictions of UDL, UD, and predictions made by Santhosh et al. based on the Modified Generalized Liquid Drop Model (MGLDM). The decay half-lives of halo nuclei from heavy elements are also calculated using the new formula and CPPMDN and compared with the predictions of UDL, UD, and the predictions made by Santhosh et al. based on the Coulomb and Proximity Potential Model (CPPM).

Інклюзивні реакції зриву та фрагментації легких кластерних ядер при проміжних енергіях

In the framework of eiconal approximation and the double folding model, a formalism for calculating inclusive spectra of particles from stripping and fragmentation reactions involving light cluster nuclei is proposed. The cross-section of the 12C(3He, d)13N reaction at an incident particle energy of 81.4 MeV and the proton spectra from the deuteron fragmentation reaction with 56 MeV energies by 12C and 27Al nuclei are described. The calculated values satisfactorily fit the corresponding experimental data.

The Intra-Group Baryons in the LEO I Pair From the VST Early-Type GAlaxy Survey

In this paper we present the deep, wide-field and multi-band imaging of the LEO I pair NGC 3379-NGC 3384, from the VST Early-type GAlaxy Survey (VEGAS). The main goal of this study is to map the intra-group baryons in the pair, in the form of diffuse light and globular clusters (GCs). Taking advantage from the large covered area, which extends for ∼ 3.9 square degrees around the pair, and the long integration time, we can map the light distribution out to ∼ 63 kpc and down to ∼ 30 mag/arcsec2 in the g band and ∼ 29 mag/arcsec2 in the r band, deeper than previous data available for this target. The map of the intra-group light (IGL) presents two very faint (μg ∼ 28-29 mag/arcsec2) streams protruding from the brightest group member NGC 3379 and elongated toward North-West and South. We estimate that the fraction of the stellar halo around NGC 3379 plus the intra-group light is ∼17±2% in both g and r bands, with an average color g-r = 0.75 ± 0.04 mag. The color distribution of the GCs appears multi-modal, with two dominant peaks at (u-r) = 1.8 mag and (u-r) = 2.1 mag, respectively. The GC population stretches from North-East to South-West and from North-West to South of the pair, in the last case overlapping with the streams of IGL, as well as the PNe distribution found by Hartke et al. (Hartke et al., A&A, 2020, 642, A46) and Hartke et al. (Hartke et al., 2022). Since these structures are elongated in the direction of the two nearby galaxies M96 and NGC 3338, they could be the remnant of a past gravitational interactions with the pair.

Manifestation of deformation and nonlocality in α and cluster decay

It is common to study the strong decay of a heavy nucleus as a tunneling phenomenon where the $\alpha$ ($^4$He) or a light nuclear cluster tunnels through the Coulomb barrier formed by its interaction with the heavier daughter nucleus. The position and width of the Coulomb barrier are determined by the total interaction potential between the two daughter nuclei. We examine the effects of including nonlocality and deformation in the interaction potential by calculating the half-lives, $t_{1/2}$, and thereby phenomenological preformation factors of several nuclei which have the possibility of decaying by emitting either an $\alpha$ or a light nuclear cluster. The effect of deformation manifests itself by a decrease in $t_{1/2}$ for all the decays studied. The effect of nonlocality is studied within two different models of the nuclear potential: the energy-independent but angular momentum ($l$) dependent Mumbai (M) potential and the energy-dependent Perey-Buck (PB) potential. The nonlocal nuclear interaction leads to a decrease in all half-lives studied. Though the decrease is larger due to the Perey-Buck potential, half-lives evaluated using the Mumbai potential show a strong sensitivity to the $l$ value in the decay. This feature of the $\alpha$ and cluster decay half-lives can provide a complementary tool in addition to scattering data which are more commonly used to fix the parameters of a nonlocal potential in literature.

Structure Characteristics of Light Cluster Nuclei with Extra Nucleons

The cluster nuclei 6Li, 6He, 10Be, and 10C are studied as systems consisting of α-particles and two extra nucleons. The structure functions of these nuclei are found within the variational approach. The charge density distributions, form factors, and pair correlation functions are presented and explained.

Towards solving the puzzle of high temperature light (anti)-nuclei production in ultra-relativistic heavy ion collisions

The creation of loosely bound objects in heavy ion collisions, e.g. light clusters, near the phase transition temperature (Tch≈155 MeV) has been a puzzling observation that seems to be at odds with Big Bang nucleosynthesis suggesting that deuterons and other clusters are formed only below a temperature T≈0.1−1 MeV. We solve this puzzle by showing that the light cluster abundancies in heavy ion reactions stay approximately constant from chemical freeze-out to kinetic freeze-out. To this aim we develop an extensive network of coupled reaction rate equations including stable hadrons and hadronic resonances to describe the temporal evolution of the abundancies of light (anti-)(hyper-)nuclei in the late hadronic environment of an ultrarelativistic heavy ion collision. It is demonstrated that the chemical equilibration of the light nuclei occurs on a very short timescale as a consequence of the strong production and dissociation processes. However, because of the partial chemical equilibrium of the stable hadrons, including the nucleon feeding from Δ resonances, the abundancies of the light nuclei stay nearly constant during the evolution and cooling of the hadronic phase. This solves the longstanding contradiction between the thermal fits and the late stage coalescence (and the Big Bang nucleosynthesis) and explains why the observed light cluster yields are compatible with both a high chemical production temperature and a late state emission as modeled by coalescence. We also note in passing that the abundancies of the light clusters in the present approach are in excellent agreement with those measured by ALICE at LHC.

Astrophysical Reaction Rates of Radiative Capture of Nucleons and Lightest Clusters on Light Nuclei

Astrophysical Reaction Rates of Radiative Capture of Nucleons and Lightest Clusters on Light Nuclei

Dynamical cluster and hypernuclei production in heavy-ion collisions

We study light cluster and hypernuclei production in heavy-ion collisions from SIS to RHIC energies based on the n-body dynamical transport approach PHQMD (Parton-Hadron-Quantum-Molecular-Dynamics). In PHQMD clusters are formed dynamically due to the interactions between baryons described on the basis of Quantum Molecular Dynamics (QMD) which allows to propagate the n-body Wigner density and n-body correlations in phase-space, which is essential for the cluster formation. The clusters are identified by the MST (Minimum Spanning Tree) or the SACA (‘Simulated Annealing Cluster Algorithm’) algorithm which finds the most-bound configuration of nucleons and clusters. Collisions among hadrons as well as Quark-Gluon-Plasma formation and parton dynamics in PHQMD are treated in the same way as in the PHSD (Parton-Hadron-String-Dynamics) transport approach. We study the time evolution of the cluster formation in the expanding medium and the stability of the clusters. We present a comparison of the PHQMD results for d, 3He as well as for the hypernuclei with experimental data.

Light and stable LinB14(n=1–5) clusters for high capacity hydrogen storage at room temperature: A DFT study

In this article, we have explored the hydrogen (H2) storage capacity of the Li doped B clusters LinB14(n = 1–5) using density functional theory (DFT). The geometrical and Bader's topological parameters indicate that the clusters adsorb H2 in the molecular form. The Li atom polarises the H2 molecules for their effective adsorption on the clusters. The LinB14 (n = 1–5) clusters are found to be stable even after H2 adsorption at room temperature. The average adsorption energy is found to be in the range of 0.12–0.14 eV/H2. Among the various clusters, the Li5B14 shows maximum H2 storage capacity (13.89 wt%) at room temperature. The ADMP simulation reveals that within few femtoseconds (fs), the H2 molecules begin to move away from the clusters and within 400 fs most of the H2 molecules moved away from the clusters.

Learning to cluster for rendering with many lights

We present an unbiased online Monte Carlo method for rendering with many lights. Our method adapts both the hierarchical light clustering and the sampling distribution to our collected samples. Designing such a method requires us to make clustering decisions under noisy observation, and making sure that the sampling distribution adapts to our target. Our method is based on two key ideas: a coarse-to-fine clustering scheme that can find good clustering configurations even with noisy samples, and a discrete stochastic successive approximation method that starts from a prior distribution and provably converges to a target distribution. We compare to other state-of-the-art light sampling methods, and show better results both numerically and visually.

Collision centrality and system size dependences of light nuclei production via dynamical coalescence mechanism

Light (anti-)nuclei in relativistic heavy-ion collisions are considered to be formed by the coalescence mechanism of (anti-)nucleons in the present work. Using a dynamical phase-space coalescence model coupled with a multi-phase transport (AMPT) model, we explore the formation of light clusters such as deuteron, triton and their anti-particles in different centralities for $^{197}$Au + $^{197}$Au collisions at $\sqrt{s_{NN}} = 39$ GeV. The calculated transverse momentum spectra of protons, deuterons, and tritons are comparable to those of experimental data from the RHIC-STAR collaboration. Both coalescence parameters $B_{2}$ for (anti-)deuteron and $B_{3}$ for triton increase with the transverse momentum as well as the collision centrality, and they are comparable with the measured values in experiments. The effect of system size on the production of light nuclei is also investigated by $^{10}$B + $^{10}$B, $^{16}$O + $^{16}$O, $^{40}$Ca + $^{40}$Ca, and $^{197}$Au + $^{197}$Au systems in central collisions. The results show that yields of light nuclei increase with system size, while the values of coalescence parameters present an opposite trend. It is interesting to see that the system size, as well as the centrality dependence of $B_A$ ($A$ = 2, 3), falls into the same group, which further demonstrates production probability of light nuclei is proportional to the size of the fireball. Furthermore, we compare our coalescence results with other models, such as the thermal model and analytic coalescence model, it seems that the description of light nuclei production is consistent with each other.

Isospin effect on quark matter instabilities

We have studied the mechanical and chemical instabilities as well as the liquid-gas-like phase transition in isospin asymmetric quark matter based on the NJL and the pNJL model. Areas of the mechanical instability region and the liquid-gas coexistence region are seen to be enlarged with a larger quark matter symmetry energy or in the presence of strange quarks. Our study shows that the light cluster yield ratio observed in relativistic heavy-ion collisions may not be affected much by the uncertainties of the isospin effect, and favors a smooth hadron-quark phase transition in compact stars as well as their mergers.

Optical crystals and light-bullets in Kerr resonators

Stable light bullets and clusters of them are presented in the monostable regime using the mean-field Lugiato–Lefever equation [Gopalakrishnan, Panajotov, Taki, and Tlidi, Phys. Rev. Lett. 126, 153902 (2021)]. It is shown that three-dimensional (3D) dissipative structures occur in a strongly nonlinear regime where modulational instability is subcritical. We provide a detailed analysis on the formation of optical 3D crystals in both the super- and sub-critical modulational instability regimes, and we highlight their link to the formation of light bullets in diffractive and dispersive Kerr resonators. We construct bifurcation diagrams associated with the formation of optical crystals in both monostable and bistable regimes. An analytical study has predicted the predominance of body-centered-cubic (bcc) crystals in the intracavity field over a large variety of other 3D solutions with less symmetry. These results have been obtained using a weakly nonlinear analysis but have never been checked numerically. We show numerically that indeed the most robust structures over other self-organized crystals are the bcc crystals. Finally, we show that light-bullets and clusters of them can occur also in a bistable regime.

Light Cluster Production in Central Symmetric Heavy-Ion Reactions from Fermi to Gev Energies

Correlations and clustering are of great importance in the study of the Nuclear Equation of State. Information on these items/aspects can be obtained using heavy-ion reactions which are described by dynamical theories. We propose a dataset that will be useful for improving the description of light cluster production in transport model approaches. The dataset combines published and new data and is presented in a form that allows direct comparison of the experiment with theoretical predictions. The dataset is ranging in bombarding energy from 32 to 1930 A MeV. In constructing this dataset, we put in evidence the existence of a change in the light cluster production mechanism that corresponds to a peak in deuteron production.

A Hybrid K-Mean and Graph Metrics Algorithm for Node Sleeping Scheduling in Wireless Sensor Network (WSN)

Wireless Sensor Networks (WSN) has proliferated in the past decade. These networks consist of massive number of battery-powered nodes distrusted over a given area. The nodes are responsible for sensing the environment and delivering the sensed data to a central point, named sink node. In order to reduce the power consumption of these nodes, sleeping/waking scheduling strategy has been proposed. In this work, a new hybrid sleeping/waking scheduling algorithm is proposed based on graph theory metrics and unsupervised K-mean machine learning algorithm. In the proposed algorithm, the sink node is responsible for calculating the metrics and clustering the nodes into three main clusters; dense, mid and light. Subsequently, the algorithm attempts to reduce the load on the nodes in light cluster in order to prolong the network lifetime. The algorithm has been simulated in 3D WSN with a clustering routing protocol. The simulation results show that the algorithm reduces the number of working sensor network nodes without affecting the network diameter. Moreover, the scheduling strategy has prolonged the network lifetime and has reduced the number of disconnected components.

Light fragment and neutron emission in high-energy proton induced spallation reactions * *Supported by the National Natural Science Foundation of China (11722546, 11675226) and the Talent Program of South China University of Technology

The dynamics of high-energy proton-induced spallation reactions on target nuclides of 56Fe, 58Ni, 107Ag, 112Cd, 184W, 181Ta, 197Au, and 208Pb are investigated with the quantum molecular dynamics transport model motivated by the China initiative Accelerator Driven System (CiADS) in Huizhou and the China Spallation Neutron Source (CSNS) in Dongguan. The production mechanism of light nuclides and fission fragments is thoroughly analyzed, and the results obtained thereby are compared with available experimental data. The statistical code GEMINI is employed in conjunction with a transport model for describing the decay of primary fragments. For the treatment of cluster emission during the preequilibrium stage, a surface coalescence model is implemented into the model. It is found that the available data in terms of total fragment yields are well reproduced in the combined approach for spallation reactions both on the heavy and light targets. The energetic light nuclides (deuteron, triton, helium isotopes etc) mainly created during the preequilibrium stage are treated within the framework of surface coalescence, whereas their evaporation is described in the conventional manner by the GEMINI code. With this combined approach, a good overall description of light clusters and neutron emission is obtained, and some discrepancies with the experimental data are discussed. Possible production of radioactive isotopes in the spallation reactions is also analyzed, i.e., the 6,8He energy spectra.

Nonequilibrium information entropy approach to ternary fission of actinides

Ternary fission of actinides probes the state of the nucleus at scission. Light clusters are produced in space and time very close to the scission point. Within the nonequilibrium statistical operator method, a generalized Gibbs distribution is constructed from the information given by the observed yields of isotopes. Using this relevant statistical operator, yields are calculated taking excited states and continuum correlations into account, in accordance with the virial expansion of the equation of state. Clusters with mass number $A \le 10$ are well described using the nonequilibrium generalizations of temperature and chemical potentials. Improving the virial expansion, in-medium effects may become of importance in determining the contribution of weakly bound states and continuum correlations to the intrinsic partition function. Yields of larger clusters, which fail to reach this quasi-equilibrium form of the relevant distribution, are described by nucleation kinetics, and a saddle-to-scission relaxation time of about 7000 fm/c is inferred. Light charged particle emission, described by reaction kinetics and virial expansions, may therefore be regarded as a very important tool to probe the nonequilibrium time evolution of actinide nuclei during fission.

Real-time indirect illumination by virtual planar area lights

This paper presents a method called Virtual Planar Area Lights (VPALs) to generate single-bounce diffuse-to-diffuse indirect illumination for dynamic scenes and light sources. Different from the VPLs (Virtual Point Lights) based methods, which extract point lights from RSM (Reflective Shadow Map), our method fits RSM by many planar regions which will be directly used as virtual light sources to generate the indirect illumination. In order to reduce the illumination errors introduced by plane fitting, we propose several strategies, including an illumination-guided plane fitting algorithm, a normal correction factor and a virtual light sources reuse strategy. Our experimental results indicate that our method can achieve a good balance between the rendering performance and quality. Compared with traditional light culling and clustering methods, the rendering consumption of our algorithm is reduced by at least 67% with the similar RMSE (Root Mean Squared Error).

Wild Olive Trees Extent in Al-Baha Region, Saudi Arabia According to Trees’ Age, Health, and Clustering Status

This study provided detailed information on the attributes of wild olive species in the Al- Baha region, Saudi Arabia. The study area lay along the Sarah mountain, encompassing the districts of Al-Qura, Al-Mandaq, Al- Baha and the southern part of Baljurashi. This indicates the preference of wild olive for high foggy mountain conditions, which was pre-determined by the study to be a medium-high vegetation density zone. Information extracted from high resolution satellite imagery Pleaides revealed that there are 717,894 wild olive trees (360 trees per km2) in the study area, covering 1,991 km2 .The districts of Al-Mandaq and Al-Baha have higher wild olive density with younger and highly clustered trees, whereas Al-Qura and Baljurashi districts have lower wild olive density, with medium clustered older trees. The districts of Al-Aqiq, Qelwa and Mekhwa have the least density of wild olive with younger trees and light clustering. Clustering behavior was enumerated directly at the sampling plots and the results depicted that the majority of wild olives occur in clusters with mostly 5-10 trees per cluster. The olive tree is found naturally in Al-Baha and can reportedly maintain its populations in natural old growth forests for several hundred years. This study identified the age of wild olive trees in the study area. The results indicated that there were more (68%) of young age class (<50 years old) of wild olive trees, whereas Baljurashi showed the highest percentage of old age class (>150 years). The majority (88.6%) of the wild olive trees were healthy, while more unhealthy trees were observed in Al-Mandaq and Al-Baha districts. As observed during the groundwork, unhealthy trees particularly due to dieback, were more discerned with juniper affecting vegetation in Al-Mandaq and South Baha, with 45% and 18% respectively. Similarly, this study recorded trace of unhealthy vegetation, with 11.4% of the wild olive trees in an unhealthy condition. This information would be essential in ‘Identifying the Landscape Preference of Wild Olive in Al-Baha Region Saudi Arabia’.

Resolving the hyper-triton yield description puzzle in high energy nuclear collisions

The recently developed hadron resonance gas model with multicomponent hard-core repulsion is used to address and resolve the long standing problem to describe the light nuclear cluster multiplicities including the hyper-triton measured by the STAR Collaboration, known as the hyper-triton chemical freeze-out puzzle. An improved description for the hadronic and light nuclear cluster data measured by STAR at the collision energy sqrt{s_{NN}} =200 GeV and by ALICE at sqrt{s_{NN}} =2.76 TeV is obtained. This is achieved by applying a new strategy of analyzing the light nuclear cluster data and by using the value for the hard-core radius of the (anti-)varLambda hyperons found in earlier work. One of the most striking results of the present work is that for the most probable scenario of chemical freeze-out for the STAR energy the obtained parameters allow to simultaneously reproduce the values of the experimental ratios S_3 and {overline{S}}_3 which were not included in the fit.