First-principles study on the diffusion behavior of Cs and I in Cr coating

Cs and I can migrate through fuel-cladding interfaces and accelerate the cladding corrosion process induced by the fuel-cladding chemical interaction.Cr coating has emerged as an important candidate for mitigating this chemical interaction.In this study,first-principles calculations were employed to investigate the diffusion behavior of Cs and I in the Cr bulk and grain boundaries to reveal the microscopic interaction mitigation mechanisms at the fuel-cladding interface.The interaction between these two fission products and the Cr coating were studied systematically,and the Cs and I temperature-dependent diffusion coefficients in Cr were obtained using Bocquet’s oversized solute-atom model and Le Claire’s nine-frequency model,respectively.The results showed that the Cs and I migration barriers were significantly lower than that of Cr,and the Cs and I diffusion coefficients were more than three orders of magnitude larger than the Cr self-diffusion coefficient within the temperature range of Generation-IV fast reactors(below 1000 K),demonstrating the strong penetration ability of Cs and I.Furthermore,Cs and I are more likely to diffuse along the grain boundary because of the generally low migration barriers,indicating that the grain boundary serves as a fast diffusion channel for Cs and I.

Two-proton radioactivity from excited states of proton-rich nuclei within Coulomb and Proximity Potential Model

In the present work,we extend the Coulomb and Proximity Potential Model(CPPM)to study two-proton(2p)radioactivity from excited states while the proximity potential is chosen as AW95 proposed by Aage Withner in 1995.Demonstration reveals that the theoretical results acquired by CPPM exhibit a high level of consistency with prior theoretical models such as the unified fission model(UFM),generalized liquid-drop model(GLDM)and effective liquid-drop model(ELDM).Furthermore,within the CPPM,we predicted the half-lives of potential 2p radioactive nuclei for which experimental data are currently unavailable.The predicted results were then assessed,compared with UFM,ELDM and GLDM models,and examined in detail.

Rapid determination of radon monitor＇s calibration factors

The monitors used to measure radon concentration must be calibrated,and the calibration factor of each measurement cycle should be determined.Thus,the determination time of calibration factors of NRL-Ⅱ radon monitors should be reduced.In this study,a method is proposed to determine the calibration factors of radon monitors rapidly.In the proposed method,the calibration factor is initially determined in the 60-min measurement cycle;the calibration factor is then identified in the other measurement cycle on the basis of the principle that the calibration factor of the same radon monitor in different measurement cycles is inversely proportional to the number of a particles produced by ^(218)Po decay in this cycle.Results demonstrate that the calculated calibration factor of the different measurement cycles is consistent with the experimental calibration factor.Therefore,this method is reliable and can be used to determine the calibration factor of radon monitors rapidly.

Adsorption and desorption of hydrogen on/from single-vacancy and double-vacancy graphenes

Adsorption and desorption of hydrogen on/from single-vacancy and double-vacancy graphenes were studied by means of first-principles calculations. The structure and stability of continuous hydrogenation in single vacancy were investigated. Several new stable structures were found, along with their corresponding energy barriers. In double-vacancy graphene, the preferred sites of H atoms were identified, and H2 molecule desorption and adsorption of from/on were calculated from the energy barriers. This work provides a systematic and comprehensive understanding of hydrogen behavior on defected graphene.

Two-proton radioactivity of the excited state within the Gamow-like and modified Gamow-like models

In this study,we systematically investigated the two-proton(2p)radioactivity half-lives from the excited state of nuclei near the proton drip line within the Gamowlike model(GLM)and modified Gamow-like model(MGLM).The calculated results were highly consistent with the theoretical values obtained using the unified fission model[Chin.Phys.C 45,124105(2021)],effective liquid drop model,and generalized liquid drop model[Acta Phys.Sin 71,062301(2022)].Furthermore,utilizing the GLM and MGLM,we predicted the 2p radioactivity halflives from the excited state for some nuclei that are not yet available experimentally.Simultaneously,by analyzing the calculated results from these theoretical models,it was found that the half-lives are strongly dependent on Qand l.

Systematic study of cluster radioactivity in trans-lead nuclei with various versions of proximity potential formalisms

In this study,based on the framework of the Coulomb and proximity potential model(CPPM),we systematically investigate the cluster radioactivity half-lives of 26 trans-lead nuclei by considering the cluster preformation probability,which possesses a simple mass dependence on the emitted cluster according to R.Blendowske and H.Walliser[Phys.Rev.Lett.61,1930(1988)].Moreover,we investigate 28 different versions of the proximity potential formalisms,which are the most complete known proximity potential formalisms proposed to describe proton radioactivity,two-proton radioactivity,αdecay,heavy-ion radioactivity,quasi-elastic scattering,fusion reactions,and other applications.The calculated results show that the modified forms of proximity potential 1977,denoted as Prox.77-12,and proximity potential 1981,denoted as Prox.81,are the most appropriate proximity potential formalisms for the study of cluster radioactivity,as the root-mean-square deviation between experimental data and relevant theoretical results obtained is the least;both values are 0.681.For comparison,the universal decay law(UDL)proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],unified formula of half-lives forαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)],and scaling law(SL)in cluster radioactivity proposed by Horoi et al.[J.Phys.G 30,945(2004)]are also used.In addition,utilizing CPPM with Prox.77-12,Prox.77-1,Prox.77-2,and Prox.81,we predict the half-lives of 51 potential cluster radioactive candidates whose cluster radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020.The predicted results are in the same order of magnitude as those obtained using the compared semi-empirical and/or empirical formulae.At the same time,the competition betweenαdecay and cluster radioactivity of these predicted nuclei is discussed.By comparing the half-lives,this study reveals thatαdecay predominates.

Systematic calculations of cluster radioactivity half-lives in trans-lead nuclei

In the present work,based on the Wentzel-Kramers-Brillouin(WKB)theory,considering the cluster preformation probability(Pc),we systematically investigate the cluster radioactivity half-lives of 22 trans-lead nuclei ranging from221Fr to242Cm.When the mass number of the emitted cluster Ac<28,Pcis obtained by the exponential relationship of Pcto theαdecay preformation probability(Pα)proposed by R.Blendowskeis et al.[Phys.Rev.Lett.61,1930(1988)],while Pαis calculated through the cluster-formation model(CFM).When Ac≥28,Pcis calculated through the charge-number dependence of Pcon the decay products proposed by Ren et al.[Phys.Rev.C70,034304(2004)].The half-lives of cluster radioactivity have been calculated by the density-dependent cluster model[Phys.Rev.C 70,034304(2004)]and by the unified formula of half-lives for alpha decay and cluster radioactivity[Phys.Rev.C 78,044310(2008)].For comparison,a universal decay law(UDL)proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a semi-empirical model for bothαdecay and cluster radioactivity proposed by Santhosh[J.Phys.G:Nucl.Part.Phys.35,085102(2008)],and a unified formula of half-lives for alpha decay and cluster radioactivity[Phys.Rev.C 78,044310(2008)]are also used.The calculated results of our work,Ni’s formula,and the UDL can well reproduce the experimental data and are better than those of Santhosh’s model.In addition,we extend this model to predict the half-lives for 51 nuclei,whose cluster radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020.

New Geiger-Nuttall law for cluster radioactivity half-lives

In this study,derived from Balasubramaniam’s formula[Phys.Rev.C 70,017301(2004)]and further considering the effect of the parent nucleus mass,blocking effect,and effect of reduced mass on cluster radioactivity half-lives,we propose a new Geiger-Nuttall law that is model-independent to systematically evaluate the halflives of this process for 16 even-even nuclei and 10 odd-A nuclei.For comparison,a single universal curve for cluster radioactivity andαdecay proposed by Poenaru[Phys.Rev.C 83,014601(2011)],a scaling law proposed by Horoi[J.Phys.G:Nucl.Part.Phys.30,945(2004)],an extension of the Viola-Seaborg formula fromαdecay to cluster radioactivity proposed by Ren et al.[Phys.Rev.C 70,034304(2004)],a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al.[Phys.Rev.C 70,017301(2004)],and a unified formula for the half-lives ofαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)]are also used.The calculated results of our new Geiger-Nuttall law are in good agreement with the experimental half-lives,with the least rms being 0.606,and are better than the compared values.Moreover,we extend this formula to predict the cluster radioactivity half-lives of 51 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.

An improved α-decay energy formula for heavy and superheavy nuclei

Based on the liquid-drop model and using the first derivative of the normalized Gaussian function to consider the shell correction,a simpleα-decay energy formula is proposed for heavy and superheavy nuclei.The values of corresponding adjustable parameters are obtained by fittingα-decay energies of 209 nuclei ranging from Z=90 to Z=118 with N≥140.The calculated results are in good agreement with the experimental data.The average and standard deviations between the experimental data and theoretical results are 0.141 and 0.190 Me V,respectively.For comparison,the reliable formulae proposed by Dong T K et al(2010,Phys.Rev.C 82,034320),Dong J M et al(2010,Phys.Rev.C 81,064309)and the WS3+nuclear mass model proposed by Wang N et al(2011,Phys.Rev.C 84,051303)are also used.The results indicate that our improved 7-parameter formula is superior to these empirical formulae and is largely consistent with the WS3+nuclear mass model.In addition,we extend this formula to predict theα-decay energies for nuclei with Z=117,118,119 and 120.The predicted results of these formulae are basically consistent.

Systematic calculations of cluster radioactivity half-lives with a screened electrostatic barrier

In this study,based on Wentzel-Kramers-Brillouin theory,we systematically investigate the cluster radioactivity half-lives of 22 nuclei ranging from^(221)Fr to^(242)Cm using a phenomenological model that considers the screened electrostatic effect of the Coulomb potential.In this model,there are two adjustable parameters,t and g,which are related to the screened electrostatic barrier and the strength of the spectroscopic factor,respectively.The calculated results indicate that this model can effectively reproduce the experimental data,with a corresponding rootmean-square deviation of 0.660.In addition,we extend this model to predict the half-lives of possible cluster radioactive candidates whose cluster radioactivities are energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2020.The predicted results are consistent with those obtained using other theoretical models and/or empirical formulas,including the universal decay law proposed by Qi et al.[Phys.Rev.C 80,044326(2009)],a semi-empirical model for bothαdecay and cluster radioactivity proposed by Santhosh et al.[J.Phys.G 35,085102(2008)],and a unified formula for the half-lives ofαdecay and cluster radioactivity proposed by Ni et al.[Phys.Rev.C 78,044310(2008)].

Systematic study of α decay half-lives for even–even nuclei within a deformed two-potential approach

In this work,we systematically study theαdecay half-lives of 196 even–even nuclei using a two-potential approach improved by considering nuclear deformation.The results show that the accuracy of this model has been improved after considering nuclear deformation.In addition,we extend this model to predict theαdecay half-lives of Z=118 and 120 isotopes by inputting theαdecay energies extracted from the Weizsacker–Skyrme-type(WS-type)mass model,a simple nuclear mass formula,relativistic continuum Hartree–Bogoliubov theory and Duflo-Zuker-19(DZ19)mass model.It is useful for identifying the new superheavy elements or isotopes for future experiments.Finally,the predictedαdecay energies and half-lives of Z=118 and 120isotopes are analyzed,and the shell structure of superheavy nuclei is discussed.It shows that the shell effect is obvious at N=184,while the shell effect at N=178 depends on the nuclear mass model.

Systematic study on α-decay half-lives of uranium isotopes with a screened electrostatic barrier

In the present work,we systematically study the α-decay half-lives of uranium(Z=92) isotopes based on the Gamow model with a screened electrostatic barrier.There are only two adjustable parameters in our model i.e.the parameter g and the screening parameter t in the Hulthen potential for considering the screened electrostatic effect of the Coulomb potential.The calculated results are in good agreement with experimental data,and the corresponding root-mean-square(rms) deviations of uranium isotopes with α transition orbital angular momentum l=0 and l=2 are 0.141 and 0.340,respectively.Moreover,we extend this model to predict α-decay half-lives of uranium isotopes whose a decay is energetically allowed or observed but not yet quantified in NUBASE2020.For comparison,the modified Hatsukawa formula(XLZ),the unified Royer formula(DZR),the universal decay law(UDL) and the Viola-Seaborg-Sobiczewski formula(VSS) are also used.The predictions are basically consistent with each other.Meanwhile,the results also indicate that N=126 shell closure is still robust at Z=92 and the spectroscopic factor S_(α) is almost the same for uranium isotopes with the same l.

Systematic study of proton radioactivity half-lives based on the relationship between Skyrme-Hartree-Fock and the macroscopic quantities of nuclear matter

In this study,we systematically investigate the proton radioactivity half-lives of 33 spherical nuclei based on the relationship between Skyrme parameters and the macroscopic quantities of nuclear matter.Using the two-potential approach with the spherical Skyrme-Hartree-Fock model,the correlation between proton radioactivity half-life and the macroscopic quantities is analyzed.Moreover,we obtain a new Skyrme parameter set by fitting the two most weighted macroscopic quantities.Compared with the Skyrme parameters MSLO and the theoretical model of proton radioactivity UDLP,the theoretical proton radioactivity half-life calculated using the new Skyrme parameter set can better reproduce the experimental data.

Systematic study of two-proton radioactivity with a screened electrostatic barrier

In this study,a phenomenological model is proposed based on Wentzel-Kramers-Brillouin(WKB)theory and applied to investigate the two-proton(2p)radioactive half-lives of nuclei near or beyond the proton drip line.The total diproton-daughter nucleus interaction potential is composed of the Hulthen-type electrostatic term and the centrifugal term.The calculated 2p radioactive half-lives can accurately reproduce the existing 10 experimental datasets of five true 2p radioactive nuclei withσ=0.736.In addition,we extend this model to predict the half-lives of possible 2p radioactive nuclei whose 2p radioactivity is energetically allowed or observed but not yet quantified in NUBASE2016.The predicted results are in agreement with those obtained using the Gamow-like model,generalized liquid drop model,Sreeja formula,and Liu formula.

α decay properties of ^(296)Og within the two-potential approach

The present work is a continuation of our previous paper[J.-G. Deng, et al., Chin. Phys. C, 41：124109 （2017）]. In the present work, the α decay half-life of the unknown nucleus 296Og is predicted within the two-potential approach and the hindrance factors of all 20 even-even nuclei in the same region as 296Og, i.e. proton number 82 〈 Z 〈 126 and neutron number 152 〈 N 〈 184, from 250Cm to 294Og, are extracted. The prediction is 1.09 ms within a factor of 5.12. In addition, based on the latest experimental data, a new set of parameters of α decay hindrance factors for the even-even nuclei in this region, considering the shell effect and proton-neutron interaction, are obtained.

Favored one proton radioactivity within a one-parameter model

In the present work,a phenomenological one-parameter model(OPM)based on the WentzelKramers-Brillouin(WKB)theory is applied to study the favored one proton radioactivity(the orbital angular momentum l taken away by the emitted proton is equal to zero)half-lives.The calculated results can reproduce the experimental data well within a factor of~3.In addition,we extend the OPM to predict the half-lives of possible favored one proton radioactivity nuclei whose decay is energetically allowed or observed but not quantified in NUBASE2020.For comparison,a universal decay law of one proton radioactivity(UDLP)is also used.It is obviously found that our predicted results are close to the ones using UDLP.The predictions are helpful for searching for the new nuclides with favored one proton radioactivity.

Two-proton radioactivity within Coulomb and proximity potential model

Considering the preformation probability of the two emitted protons in the parent nucleus,we extend the Coulomb and proximity potential model(CPPM)to systematically study two-proton(2p)radioactivity half-lives of the nuclei close to proton drip line.The proximity potential chosen is Prox.81 proposed by Blocki et al.in 1981.Furthermore,we apply this model to predict the half-lives of possible 2p radioactive candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2016.The predicted results are in good agreement with those from other theoretical models and empirical formulas,namely the effective liquid drop model(ELDM),generalized liquid drop model(GLDM),Gamow-like model,Sreeja formula and Liu formula.

Systematic study of two-proton radioactivity half-lives using the two-potential and Skyrme-Hartree-Fock approaches

In this work,we systematically study the two-proton(2_(p))radioactivity half-lives using the two-potential approach,and the nuclear potential is obtained using the Skyrme-Hartree-Fock approach and the Skyrme effective interaction of SLy8.For true 2_(p) radioactivity(Q2_(p)>0 and Q_(p)<0,where Q_(p) and Q2_(p) are the released energies of the one-proton and two-proton radioactivity,respectively),the standard deviation between the experimental half-lives and our theoretical calculations is 0.701.In addition,we extend this model to predict the half-lives of 15 possible 2_(p) radioactivity candidates with Q2_(p)>0 obtained from the evaluated atomic mass table AME2016.The calcu-lated results indicate a clear linear relationship between the logarithmic 2_(p) radioactivity half-lives(logio10T_(1/2))and coulomb parameters[(Z_(d)^(0.8)+l^(0.25))Q_(2_(p))^(-1/2)]considering the effect of orbital angular momentum proposed by Liu et al.[Chin.Phys.C 45,024108(2021)].For comparison,the generalized liquid drop model(GLDM),effective liquid drop model(ELDM),and Gamow-like model are also used.Our predicted results are consistent with those obtained using other relevant models.