Study of Deuteron Separation Energy Based on Bayesian Neural Network Approach

Deuteron separation energy is not only the basis for validating the nuclear mass models and nucleon-nucleon interaction potential,but also can determine the stability of a nuclide to certain extent.Bayesian neural network(BNN)approach,which has strong predictive power and can naturally give theoretical errors of predicted values,had been successfully applied to study the different kinds of separations except the deuteron separation.In this paper,several typical nuclear mass models,such as macroscopic model BW2,macroscopic-microscopic model WS4,and microscopic model HFB-31,are chosen to study the deuteron separation energy combining BNN approach.The root-mean-square deviations of these models are partly reduced.In addition,the inclusion of physical parameters related to the pair and shell effects in the input layer can further improve the theoretical accuracy for the deuteron separation energy.The results show that the theoretical predictions are more reliable as more physical features of BNN approach are included.

Machine learning the nuclear mass

Background:The masses of-2500 nuclei have been measured experimentally;however,>7000 isotopes are predicted to exist in the nuclear landscape from H(Z=1)to Og(Z=118)based on various theoretical calculations.Exploring the mass of the remaining isotopes is a popular topic in nuclear physics.Machine learning has served as a powerful tool for learning complex representations of big data in many fields.Purpose:We use Light Gradient Boosting Machine(LightGBM),which is a highly efficient machine learning algorithm,to predict the masses of unknown nuclei and to explore the nuclear landscape on the neutron-rich side from learning the measured nuclear masses.Methods:Several characteristic quantities(e.g.,mass number and proton number)are fed into the LightGBM algorithm to mimic the patterns of the residual δ(Z,A)between the experimental binding energy and the theoret-ical one given by the liquid-drop model(LDM),Duflo–Zucker(DZ,also dubbed DZ28)mass model,finite-range droplet model(FRDM,also dubbed FRDM2012),as well as the Weizsacker–Skyrme(WS4)model to refine these mass models.Results:By using the experimental data of 80%of known nuclei as the training dataset,the root mean square devia-tions(RMSDs)between the predicted and the experimental binding energy of the remaining 20%are approximately 0.234±0.022,0.213±0.018,0.170±0.011,and 0.222±0.016 MeV for the LightGBM-refined LDM,DZ model,WS4 model,and FRDM,respectively.These values are approximately 90%,65%,40%,and 60%smaller than those of the corresponding origin mass models.The RMSD for 66 newly measured nuclei that appeared in AME2020 was also significantly improved.The one-neutron and two-neutron separation energies predicted by these refined models are consistent with several theoretical predictions based on various physical models.In addition,the two-neutron separation energies of several newly measured nuclei(e.g.,some isotopes of Ca,Ti,Pm,and Sm)pre-dicted with LightGBM-refined mass models are also in good agreement with the latest experimental data.Conclusions:LightGBM can be used to refine theoretical nuclear mass models and predict the binding energy of unknown nuclei.Moreover,the correlation between the input characteristic quantities and the output can be inter-preted by SHapley additive exPlanations(a popular explainable artificial intelligence tool),which may provide new insights for developing theoretical nuclear mass models.

Properties of Z=114 super-heavy nuclei

The center of the stability island of super-heavy nuclei(SHN)is the subject of intense experimental and theoretical investigations and has potential technological applications.^(298)^(114) Fl lies in the Z=114 isotopic chain as a persuasive candidate of the spherical double-magic nucleus in SHN,and in this study,the calculations of nuclear binding energies,one-nucleon and two-nucleon separation energies,a-decay energies,and the corresponding halflives provide strong evidence for this point.These calculations within an improved Weizsacker-Skyrme nuclear mass model(WS*)were performed and compared with the calculations of the finite-range droplet model(FRDM2012)and experimental data for Z=114 isotopes and N=184 isotones.Concurrently,the corresponding single-particle levels in a Woods-Saxon potential well with a spin-orbit term are calculated,which can be used as a powerful indicator to identify the shell effects existing in114298Fl.Both the study of the properties of the isotopic chain and microphysical quantities provide a vital signal that ^(298)^(114) Fl is a spherical double-magic nucleus and also the center of the SHN.

Entanglement of two distinguishable atoms in a rectangular waveguide:Linear approximation with single excitation

We investigate the entanglement dynamics of two distinguishable two-level systems(TLSs)characterized by energy differenceδlocated inside a rectangular hollow metallic waveguide of transverse dimensions a and b.The effects of energy differenceδand the inter-TLS distance on the time evolution of the concurrence of the TLSs are examined in the single excitation subspace when the energy separation of the TLS is far away from the cutoff frequencies of the transverse mode.

Energy Separation and Explicit Dynamic Analysis of Low Temperature Impact Toughness of Transmission Tower Material Q420B

To determine the physical significance of the impact toughness parameters and accurately characterize the low temperature impact toughness of transmission tower material Q420 B,the finite element model of Charpy impact test is established on the basis of experiment.The simulation and test results are verified,and the specimen fracture is analyzed by scanning electron microscope.The formation and growth mechanism of the crack are dynamically analyzed.On this basis,energy separation method is used to investigate the effect of low temperature on impact toughness.The results show that the simulation and test results are in good agreement,and the ductile-brittle transition temperature of Q420 B is about-50 ℃.The breaking process of the specimen is divided into the crack formation and propagation.When temperature drops from 20 to-60 ℃,the crack propagation energy decreases from 51.0 to 11.9 J,the crack formation energy reduces from 39.9 to 15.8 J,and the fracture time of the material drops from 1.8 to 0.6 ms.

Experimental determination of one-and two-neutron separation energies for neutron-rich copper isotopes

A method is proposed to determine the one-neutron Sn or two-neutron S2n separation energy of neutron- rich isotopes. Relationships between Sn （S2n） and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64A MeV S6Kr 9Be reaction. Sn, S2n, and B/A for the very neutron-rich 77,78,79Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between Sn, S2n and isotopic cross sections can be used to find the location of neutron drip line isotopes.

Use of oleaginous plants in phytotreatment of grey water and yellow water from source separation of sewage

Efficient and economic reuse of waste is one of the pillars of modern environmental engineering. In the field of domestic sewage management,source separation of yellow（urine）,brown（faecal matter）and grey waters aims to recover the organic substances concentrated in brown water,the nutrients（nitrogen and phosphorous）in the urine and to ensure an easier treatment and recycling of grey waters. With the objective of emphasizing the potential of recovery of resources from sewage management,a lab-scale research study was carried out at the University of Padova in order to evaluate the performances of oleaginous plants（suitable for biodiesel production）in the phytotreatment of source separated yellow and grey waters. The plant species used were Brassica napus（rapeseed）,Glycine max（soybean）and Helianthus annuus（sunflower）. Phytotreatment tests were carried out using 20 L pots. Different testing runs were performed at an increasing nitrogen concentration in the feedstock. The results proved that oleaginous species can conveniently be used for the phytotreatment of grey and yellow waters from source separation of domestic sewage,displaying high removal efficiencies of nutrients and organic substances（nitrogen 〉 80%; phosphorous 〉 90%; COD nearly 90%）. No inhibition was registered in the growth of plants irrigated with different mixtures of yellow and grey waters,where the characteristics of the two streams were reciprocally and beneficially integrated.

Unshackling the reversible capacity of SiO_(x)/graphite-based full cells via selective LiF-induced lithiation

Composite Si@SiO_(x)/C anodes with high specific capacity are considered the most promising alternatives to graphite in industrial lithium-ion batteries.However,their cycling stability remains a limiting factor,which originates from the severe volume deformation of silicon-derived species.In this work,the cyclabilities of composite anodes are improved by unshackling the highly reversible lithium storage capabilities from the redundancy capacity of the anode materials.A selective LiF-induced lithiation strategy is proposed based on exploiting interface separation energy differences between LiF and the active materials.An interesting preferential redeposition of LiF is observed at the Si@SiO_(x) particles,which differentiates the otherwise similar lithiation potentials of LiC_(x) and Li_(15)Si_(4),thereby enabling lithium storage in graphite that was previously underused.The resulting full cell exhibits better rate and cycling performances without sacrificing specific capacity.In an ultra-high area capacity full cell(4.9 mA h cm^(-2)),the capacity retention increases markedly from 66.1% to 94.2% after 300 cycles.The selective lithiation strategy developed herein is feasible for practical industrial applications,and importantly,it requires no changes to the existing mature lithium-ion battery manufacturing process.This study offers a new approach for the development of silicon/graphite composite anodes with long cycling lifetimes.

Reevaluation of thermonuclear reaction rate of ^(50)Fe(p,γ)^(51)Co

The thermonuclear rate of the 50Fe（p, γ）51Co reaction in the Type I X-ray bursts （XRBs） temperature range has been reevaluated based on a recent precise mass measurement at CSRe Lanzhou, where the proton separa- tion energy Sp=142±77 keV has been determined firstly for the ~1Co nucleus. Comparing to the previous theoretical predictions, the experimental Sp value has much smaller uncertainty. Based on the nuclear shell model and mirror nuclear structure information, we have calculated two sets of thermonuclear rates for the 50Fe（p, γ）51Coreaction by utilizing the experimental Sp value. It shows that the statistical-model calculations are not ideally applicable for this reaction primarily because of the low density of low-lying excited states in 51Co. In this work, we recommend that a set of new reaction rates based on the mirror structure of 51Cr should be incorporated in future astrophysical network calculations.

Improved macroscopic microscopic mass formula

A nuclear mass formula based on the macroscopic microscopic approach is proposed,in which the number of model parameters is reduced compared with other macroscopic microscopic models.The root mean square(RMS)deviation with respect to 2314 training sets(measured nuclear masses)is reduced to 0.447 MeV,and the calculated value of each nucleus is no more than 0.8%different from the experimental value.The single and two nucleon separation energies and the shell gaps are calculated to test the model.The shell corrections and double magic number of superheavy nuclei are also analyzed.

Properties of Zr hypernuclei in deformed Skyrme Hartree-Fock approach

Properties of the even-N Zr isotopes and their corresponding single-Λ and double-Λ hypernuclei are studied in the deformed Skyrme-Hartree-Fock approach. Binding energy, the two-neutron separation energies, radii are studied from beta-stable zone to the neutron drip line in this paper. The neutron drip line nuclei predicted with SLy4 and SkI4 interactions are 122Zr and 138Zr, respectively. The neutron drip line of single-Λ and double-Λ hypernuclei are Λ139Zr and 2Λ142 Zr with SkI4 interaction, respectively. The predicted hyperon drip line hypernuclei with 80Zr and 138Zr cores are 20Λ100Zr and 50Λ188Zr, respectively.

Mass excess of ^(69)Br and the rp process

The proton separation energy Sp of -786.07±11.49 keV has been evaluated for 69Br from a least squares fit of mass difference of analog states versus α/A1/3, where a is the average charge of the mirror nuclei and A is the mass number. The extracted Sp value is indicative of the rapid proton-capture process rp, and subsequent Type I X-ray bursts.

The Ame2020 atomic mass evaluation(II).Tables,graphs and references

This is the second part of the new evaluation of atomic masses,Ame2020.Using least-squares adjustments to all evaluated and accepted experimental data,described in Part I,we derived tables with numerical values and graphs which supersede those given in Ame2016.The first table presents the recommended atomic mass values and their uncertainties.It is followed by a table of the influences of data on primary nuclides,a table of various reaction and decay energies,and finally,a series of graphs of separation and decay energies.The last section of this paper provides all input data references that were used in the Ame2020 and the Nubase2020 evaluations.

The AME2016 atomic mass evaluation (Ⅱ).Tables,graphs and references

This paper is the second part of the new evaluation of atomic masses, AME2016. Using least-squares adjustments to all evaluated and accepted experimental data, described in Part I, we derive tables with numerical values and graphs to replace those given in AME2012. The first table lists the recommended atomic mass values and their uncertainties. It is followed by a table of the influences of data on primary nuclides, a table of various reaction and decay energies, and finally, a series of graphs of separation and decay energies. The last section of this paper lists all references of the input data used in the AME2016 and the NUBASE2016 evaluations （first paper in this issue）.

The study of key design parameters effects on the vortex tube performance

In this paper, energy separation effect in a vortex tube has been investigated using a CFD model. Thenumerical simulation has been done due to the complex structure of flow. The governing equationshave been solved by FLUENT code in 2D and 3D compressible and turbulent model. The effects ofgeometrical and thermo-physical parameters have been investigated. The results have shown that theoptimum length to diameter ratio is from 25 to 35. Increasing the number of nozzles from 2 to 4 withconvergent shape is found to be an efficient configuration for the swirl generator. The optimum valueof orifice diameter to tube diameter ratio, for the maximum cold air temperature difference and efficiency,has been determined to be around 0.58. The results show that if the inlet pressure increases upto a critical value, the efficiency will increase. Nevertheless, if it increases to higher values, the efficiencywill decrease. Moreover, it is found out that increasing the cold fraction decreases the coldtemperature difference and efficiency.