Pub Date : 2025-12-24DOI: 10.1016/j.nuclphysa.2025.123319
A. Gokul, A.K. Rhine Kumar
The study of atomic nuclei exemplifies the challenge of solving many-body systems, where understanding nuclear structure unveils some of the universe’s deepest mysteries. Since the 1930s, molecular states and nucleon clustering in nuclei have been a topic of great interest. To explore these phenomena, we utilize the Relativistic Hartree-Bogoliubov (RHB) method, which naturally incorporates key relativistic effects such as scalar and vector potentials along with spin-orbit interactions. This research focuses on nucleon clustering in hot nuclei, employing the RHB framework at finite temperatures (FT-RHB). Key parameters, such as the density profile and nucleon-nucleon correlation function, play a crucial role in revealing the mechanisms of cluster formation and deeper aspects of nuclear structure at high temperatures.
{"title":"Clustering in hot 28Si","authors":"A. Gokul, A.K. Rhine Kumar","doi":"10.1016/j.nuclphysa.2025.123319","DOIUrl":"10.1016/j.nuclphysa.2025.123319","url":null,"abstract":"<div><div>The study of atomic nuclei exemplifies the challenge of solving many-body systems, where understanding nuclear structure unveils some of the universe’s deepest mysteries. Since the 1930s, molecular states and nucleon clustering in nuclei have been a topic of great interest. To explore these phenomena, we utilize the Relativistic Hartree-Bogoliubov (RHB) method, which naturally incorporates key relativistic effects such as scalar and vector potentials along with spin-orbit interactions. This research focuses on nucleon clustering in hot nuclei, employing the RHB framework at finite temperatures (FT-RHB). Key parameters, such as the density profile and nucleon-nucleon correlation function, play a crucial role in revealing the mechanisms of cluster formation and deeper aspects of nuclear structure at high temperatures.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123319"},"PeriodicalIF":2.5,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.nuclphysa.2025.123313
Rayees Ahmad Yatoo , Sunil Kalkal , Akhil Jhingan
The dynamics of sub-barrier fusion reactions are well explained by incorporating channel coupling effects to various degrees of freedom, such as deformations and vibrations, within the coupled channel formalism. In many systems, sub-barrier fusion cross-sections are enhanced by couplings to inelastic excited states and nucleon transfer channels with positive Q-values. However, several systems show no such effect from positive Q-value transfer channels. Conventional coupled channel approaches effectively handle even-even systems, but for odd-even systems, odd-A nuclei are often approximated as pure rotors or vibrators, assuming ground state spin-parity and neglecting spin reorientation effects. Furthermore, single nucleon transfer is not included in codes like CCFULL, which only account for ground-state pair transfers without considering transfers involving excited states. To address these limitations, the quantum mechanical coupled reaction channel (CRC) code FRESCO is employed. For the 19F + 68Zn system, experimental data are explained by including couplings to inelastic states of both projectile and target. However, for 19F + 54,56Fe, 64Zn and 142,150Nd systems, inelastic couplings alone fail to reproduce fusion excitation functions (EFs). Couplings to one-proton (pickup) or triton (stripping) transfer channels with positive Q-values show no significant effect on sub-barrier fusion cross-sections. Overall, CRC calculations indicate that coupling to inelastic states of both projectile and target enhance sub-barrier fusion cross-sections. The treatment of the projectile/target nuclei based on certain assumptions has resulted in different sub-barrier fusion cross-sections in earlier studies. The current study suggests that channel coupling effects on fusion excitation function is a complex process in interaction with odd-A projectile and one needs to include exact spin-parity of odd-A nuclei in theoretical calculations.
{"title":"Disentangling channel coupling effects in interactions with 19F projectile using a coupled reaction channel approach","authors":"Rayees Ahmad Yatoo , Sunil Kalkal , Akhil Jhingan","doi":"10.1016/j.nuclphysa.2025.123313","DOIUrl":"10.1016/j.nuclphysa.2025.123313","url":null,"abstract":"<div><div>The dynamics of sub-barrier fusion reactions are well explained by incorporating channel coupling effects to various degrees of freedom, such as deformations and vibrations, within the coupled channel formalism. In many systems, sub-barrier fusion cross-sections are enhanced by couplings to inelastic excited states and nucleon transfer channels with positive Q-values. However, several systems show no such effect from positive Q-value transfer channels. Conventional coupled channel approaches effectively handle even-even systems, but for odd-even systems, odd-A nuclei are often approximated as pure rotors or vibrators, assuming ground state spin-parity and neglecting spin reorientation effects. Furthermore, single nucleon transfer is not included in codes like CCFULL, which only account for ground-state pair transfers without considering transfers involving excited states. To address these limitations, the quantum mechanical coupled reaction channel (CRC) code FRESCO is employed. For the <sup>19</sup>F + <sup>68</sup>Zn system, experimental data are explained by including couplings to inelastic states of both projectile and target. However, for <sup>19</sup>F + <sup>54,56</sup>Fe, <sup>64</sup>Zn and <sup>142,150</sup>Nd systems, inelastic couplings alone fail to reproduce fusion excitation functions (EFs). Couplings to one-proton (pickup) or triton (stripping) transfer channels with positive Q-values show no significant effect on sub-barrier fusion cross-sections. Overall, CRC calculations indicate that coupling to inelastic states of both projectile and target enhance sub-barrier fusion cross-sections. The treatment of the projectile/target nuclei based on certain assumptions has resulted in different sub-barrier fusion cross-sections in earlier studies. The current study suggests that channel coupling effects on fusion excitation function is a complex process in interaction with odd-A projectile and one needs to include exact spin-parity of odd-A nuclei in theoretical calculations.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123313"},"PeriodicalIF":2.5,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.nuclphysa.2025.123314
M. Bhuyan , Shilpa Rana , Raj Kumar
Understanding the role of nuclear structure in heavy-ion fusion reactions is crucial, especially in the low-energy regime where nuclear shape and density profiles significantly influence the reaction dynamics. In this work, we investigate the fusion reaction as an illustrative case by employing three different nuclear density descriptions, namely the relativistic mean-field (RMF) formalism, the Skyrme-Hartree-Fock (SHF) approach, and the two-parameter Fermi (2pF) formula. These densities are folded with relativistic R3Y and non-relativistic M3Y effective nucleon-nucleon (NN) interactions to obtain six different nuclear potentials. Furthermore, the role of quadrupole β2 and higher-order hexadecapole β4 deformations of the target nucleus is included in the calculations of nuclear densities, fusion barrier characteristics, and cross-sections. By comparing barrier heights at different orientations, it is observed that the M3Y interaction provides higher barriers than the R3Y interaction. Among the densities, the 2pF yields the highest fusion barrier, while the SHF yields the lowest. The inclusion of β2 and β4 deformations results in strong orientation dependence, modifying the fusion barrier, especially at . Further, the inclusion of β4 deformation of the 154Sm results in a lowering of the fusion barrier height compared to only β2 deformation, except for target orientation angles 36∘ < θ2 < 72∘. The highest cross-sections are obtained with SHF densities, followed by RMF densities, whereas the 2pF densities underestimate the experimental data. A better match with the experimental cross-section is achieved when structural effects, such as β2 and β4 deformations, are included in the SHF and RMF densities, along with the R3Y NN interaction. These findings underline the importance of incorporating detailed nuclear structure effects for a reliable description of heavy-ion fusion dynamics.
{"title":"Role of various nuclear densities and higher-order deformations on the dynamics of 16O+154Sm fusion reaction","authors":"M. Bhuyan , Shilpa Rana , Raj Kumar","doi":"10.1016/j.nuclphysa.2025.123314","DOIUrl":"10.1016/j.nuclphysa.2025.123314","url":null,"abstract":"<div><div>Understanding the role of nuclear structure in heavy-ion fusion reactions is crucial, especially in the low-energy regime where nuclear shape and density profiles significantly influence the reaction dynamics. In this work, we investigate the <span><math><mrow><msup><mrow></mrow><mn>16</mn></msup><mi>O</mi><msup><mo>+</mo><mn>154</mn></msup><mtext>Sm</mtext></mrow></math></span> fusion reaction as an illustrative case by employing three different nuclear density descriptions, namely the relativistic mean-field (RMF) formalism, the Skyrme-Hartree-Fock (SHF) approach, and the two-parameter Fermi (2pF) formula. These densities are folded with relativistic R3Y and non-relativistic M3Y effective nucleon-nucleon (NN) interactions to obtain six different nuclear potentials. Furthermore, the role of quadrupole <em>β</em><sub>2</sub> and higher-order hexadecapole <em>β</em><sub>4</sub> deformations of the target nucleus is included in the calculations of nuclear densities, fusion barrier characteristics, and cross-sections. By comparing barrier heights at different orientations, it is observed that the M3Y interaction provides higher barriers than the R3Y interaction. Among the densities, the 2pF yields the highest fusion barrier, while the SHF yields the lowest. The inclusion of <em>β</em><sub>2</sub> and <em>β</em><sub>4</sub> deformations results in strong orientation dependence, modifying the fusion barrier, especially at <span><math><mrow><msub><mi>θ</mi><mn>2</mn></msub><mo>=</mo><msup><mn>0</mn><mo>∘</mo></msup></mrow></math></span>. Further, the inclusion of <em>β</em><sub>4</sub> deformation of the <sup>154</sup>Sm results in a lowering of the fusion barrier height compared to only <em>β</em><sub>2</sub> deformation, except for target orientation angles 36<sup>∘</sup> < <em>θ</em><sub>2</sub> < 72<sup>∘</sup>. The highest cross-sections are obtained with SHF densities, followed by RMF densities, whereas the 2pF densities underestimate the experimental data. A better match with the experimental cross-section is achieved when structural effects, such as <em>β</em><sub>2</sub> and <em>β</em><sub>4</sub> deformations, are included in the SHF and RMF densities, along with the R3Y NN interaction. These findings underline the importance of incorporating detailed nuclear structure effects for a reliable description of heavy-ion fusion dynamics.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123314"},"PeriodicalIF":2.5,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-20DOI: 10.1016/j.nuclphysa.2025.123318
Cafer Mert Yeşilkanat , Serkan Akkoyun
Accurate prediction of Gamow-Teller (GT) beta decay matrix elements [] is essential for elucidating complex nuclear structure phenomena and understanding astrophysical processes. In this study, we employed five advanced machine learning models (Cubist, Support Vector Regression, Extreme Gradient Boosting, Random Forest, and Bayesian Regularized Neural Networks) to predict GT beta decay matrix elements in -shell nuclei, using experimental data from NNDC/ENSDF, NUBASE2016, and AME2016. This study systematically compared the predictive performance of traditional theoretical approaches (including the USDB, IM-SRG, CCEI, and CEFT) to that of advanced machine learning models trained based on experimental observations. Our primary objective was to determine whether data-driven models could achieve higher predictive accuracy than computationally expensive theoretical models by learning the complex and nonlinear relationships among experimental parameters that reflect nuclear structure and decay dynamics. The results demonstrate that the Cubist model achieves a significantly lower RMSE (0.073 in the full parameter modeling approach and 0.112 in the reduced parameter modeling approach) and high coefficients of determination (R² = 0.901 and 0.919, respectively), thereby outperforming traditional methods. Furthermore, SHapley Additive exPlanations (SHAP) analysis revealed that a minimal set of critical nuclear parameters predominantly governs GT decay dynamics, thereby enhancing model interpretability without compromising predictive accuracy. Complementing these findings, an online calculator was developed to facilitate rapid, high-fidelity predictions of GT matrix elements. Overall, our study demonstrates that a data-driven approach outperforms established theoretical models. More importantly, by identifying the minimal set of physical observables that govern GT transitions, our work provides crucial insights into the underlying physics of nuclear structure and offers a new benchmark for refining future theoretical models and astrophysical calculations.
{"title":"Accurate prediction of Gamow-Teller beta-decay matrix elements via machine learning: implications for nuclear structure","authors":"Cafer Mert Yeşilkanat , Serkan Akkoyun","doi":"10.1016/j.nuclphysa.2025.123318","DOIUrl":"10.1016/j.nuclphysa.2025.123318","url":null,"abstract":"<div><div>Accurate prediction of Gamow-Teller (GT) beta decay matrix elements [<span><math><mrow><mi>M</mi><mo>(</mo><mrow><mi>G</mi><mi>T</mi></mrow><mo>)</mo></mrow></math></span>] is essential for elucidating complex nuclear structure phenomena and understanding astrophysical processes. In this study, we employed five advanced machine learning models (Cubist, Support Vector Regression, Extreme Gradient Boosting, Random Forest, and Bayesian Regularized Neural Networks) to predict GT beta decay matrix elements in <span><math><mrow><mi>s</mi><mi>d</mi></mrow></math></span>-shell nuclei, using experimental data from NNDC/ENSDF, NUBASE2016, and AME2016. This study systematically compared the predictive performance of traditional theoretical approaches (including the USDB, IM-SRG, CCEI, and CEFT) to that of advanced machine learning models trained based on experimental observations. Our primary objective was to determine whether data-driven models could achieve higher predictive accuracy than computationally expensive theoretical models by learning the complex and nonlinear relationships among experimental parameters that reflect nuclear structure and decay dynamics. The results demonstrate that the Cubist model achieves a significantly lower RMSE (0.073 in the full parameter modeling approach and 0.112 in the reduced parameter modeling approach) and high coefficients of determination (<em>R</em>² = 0.901 and 0.919, respectively), thereby outperforming traditional methods. Furthermore, SHapley Additive exPlanations (SHAP) analysis revealed that a minimal set of critical nuclear parameters predominantly governs GT decay dynamics, thereby enhancing model interpretability without compromising predictive accuracy. Complementing these findings, an online calculator was developed to facilitate rapid, high-fidelity predictions of GT matrix elements. Overall, our study demonstrates that a data-driven approach outperforms established theoretical models. More importantly, by identifying the minimal set of physical observables that govern GT transitions, our work provides crucial insights into the underlying physics of nuclear structure and offers a new benchmark for refining future theoretical models and astrophysical calculations.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123318"},"PeriodicalIF":2.5,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.nuclphysa.2025.123310
Golda Komalan Satheedas , H. Singh , Kavita Kavita , Mohit Kumar , N. Saneesh , A. Jhingan , P. Sugathan , C. Yadav , R. Kumar , R. Dubey , Abhishek Yadav , Neeraj Kumar , A. Banerjee , Anjali Rani , Kavita Rani , J.R. Acharya , S. Noor , S.K. Duggi
Fission fragment mass ratio distributions have been measured for the reactions 19F+178Hf and 16O + 181Ta, both leading to the same compound nucleus, 197Tl, at near-Coulomb barrier energies. The measured fission fragment mass width for both these systems does not show any substantial deviation from the statistical model predictions, which indicates the absence of non-compound nuclear reactions like quasi-fission. The measured mass widths of both the reactions at the same excitation energy are comparable within the experimental uncertainty and show a gradual increase with excitation energy. No noticeable influence of effect of entrance channel mass asymmetry on fragment mass distribution in these reactions, which differs from the previously reported entrance channel-dependent variation in average pre-scission neutron multiplicity.
{"title":"Exploring the effect of entrance channel mass asymmetry in the fission of 197Tl* nucleus","authors":"Golda Komalan Satheedas , H. Singh , Kavita Kavita , Mohit Kumar , N. Saneesh , A. Jhingan , P. Sugathan , C. Yadav , R. Kumar , R. Dubey , Abhishek Yadav , Neeraj Kumar , A. Banerjee , Anjali Rani , Kavita Rani , J.R. Acharya , S. Noor , S.K. Duggi","doi":"10.1016/j.nuclphysa.2025.123310","DOIUrl":"10.1016/j.nuclphysa.2025.123310","url":null,"abstract":"<div><div>Fission fragment mass ratio distributions have been measured for the reactions <sup>19</sup>F+<sup>178</sup>Hf and <sup>16</sup>O + <sup>181</sup>Ta, both leading to the same compound nucleus, <sup>197</sup>Tl, at near-Coulomb barrier energies. The measured fission fragment mass width for both these systems does not show any substantial deviation from the statistical model predictions, which indicates the absence of non-compound nuclear reactions like quasi-fission. The measured mass widths of both the reactions at the same excitation energy are comparable within the experimental uncertainty and show a gradual increase with excitation energy. No noticeable influence of effect of entrance channel mass asymmetry on fragment mass distribution in these reactions, which differs from the previously reported entrance channel-dependent variation in average pre-scission neutron multiplicity.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123310"},"PeriodicalIF":2.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite substantial advances in nuclear physics, certain subtle aspects remain unresolved, such as the neck rupture process during fission. Particle emission near the scission stage provides valuable insights into this process. This work discusses recent experimental results from the BARC-TIFR Pelletron LINAC Facility (PLF) at Mumbai on heavy-ion induced fission using charged particle emissions. Fission and fission like processes have direct relevance to research pertaining to super heavy elements synthesis. Fission process also facilitates study about a fundamental property of finite nuclear matter; nuclear viscosity. Several questions about the nuclear viscosity are still unanswered. Particle emission during the fission process presents a potential probe to study entire fission process and nuclear viscosity. Recent observations on some novel aspects about nuclear scission from our ongoing program at PLF are presented here.
{"title":"Observation of novel features in heavy-ion induced fission using charged particle emissions","authors":"Y.K. Gupta , G.K. Prajapati , Pawan Singh , N. Sirswal , B.N. Joshi","doi":"10.1016/j.nuclphysa.2025.123315","DOIUrl":"10.1016/j.nuclphysa.2025.123315","url":null,"abstract":"<div><div>Despite substantial advances in nuclear physics, certain subtle aspects remain unresolved, such as the neck rupture process during fission. Particle emission near the scission stage provides valuable insights into this process. This work discusses recent experimental results from the BARC-TIFR Pelletron LINAC Facility (PLF) at Mumbai on heavy-ion induced fission using charged particle emissions. Fission and fission like processes have direct relevance to research pertaining to super heavy elements synthesis. Fission process also facilitates study about a fundamental property of finite nuclear matter; nuclear viscosity. Several questions about the nuclear viscosity are still unanswered. Particle emission during the fission process presents a potential probe to study entire fission process and nuclear viscosity. Recent observations on some novel aspects about nuclear scission from our ongoing program at PLF are presented here.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123315"},"PeriodicalIF":2.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1016/j.nuclphysa.2025.123307
Queena, Mukul Kumar, Sunil Kumar, Raj K. Jagota, Shashi K. Dhiman
The nuclear symmetry energy is fundamental in nuclear astrophysics, influencing phenomena from nuclear structure to gravitational collapse and neutron star formation. Both the symmetry energy and its linear density dependence (L), are critical inputs for numerous nuclear physics and astrophysics applications, as they play a key role in determining properties such as neutron skin thickness (Δrnp) and neutron star radius. Recent results from parity-violating electron scattering experiments on 208Pb (PREX-II: The Lead Radius Experiment)) have offered new insights into these fields. Specifically, the PREX-II experiment has provided a neutron skin thickness for 208Pb of fm. This measurement helps to constrain the nuclear symmetry energy in laboratory environments. In this study, we propose several interactions (SRQs) based on relativistic energy density functionals that correspond to different values of Δrnp for 208Pb, as derived from the PREX-II limits. We observe a correlation between Δrnp of 208Pb and L. We compute the equations of state for nucleonic matter under β - equilibrium conditions for proposed interactions. We also discuss in detail the effects of Δrnp and L on nuclear matter and neutron star properties. Additionally, these interactions are utilized to explore the characteristics of rotating neutron stars.
{"title":"The role of nuclear symmetry energy and neutron skin thickness of 208Pb in controlling the underlying physics of neutron star","authors":"Queena, Mukul Kumar, Sunil Kumar, Raj K. Jagota, Shashi K. Dhiman","doi":"10.1016/j.nuclphysa.2025.123307","DOIUrl":"10.1016/j.nuclphysa.2025.123307","url":null,"abstract":"<div><div>The nuclear symmetry energy is fundamental in nuclear astrophysics, influencing phenomena from nuclear structure to gravitational collapse and neutron star formation. Both the symmetry energy and its linear density dependence (L), are critical inputs for numerous nuclear physics and astrophysics applications, as they play a key role in determining properties such as neutron skin thickness (Δ<em>r<sub>np</sub></em>) and neutron star radius. Recent results from parity-violating electron scattering experiments on <sup>208</sup>Pb (PREX-II: The Lead Radius Experiment)) have offered new insights into these fields. Specifically, the PREX-II experiment has provided a neutron skin thickness for <sup>208</sup>Pb of <span><math><mrow><mstyle><mi>Δ</mi></mstyle><msub><mi>r</mi><mrow><mi>n</mi><mi>p</mi></mrow></msub><mo>=</mo><mn>0.283</mn><mo>±</mo><mn>0.071</mn></mrow></math></span> fm. This measurement helps to constrain the nuclear symmetry energy in laboratory environments. In this study, we propose several interactions (SRQs) based on relativistic energy density functionals that correspond to different values of Δ<em>r<sub>np</sub></em> for <sup>208</sup>Pb, as derived from the PREX-II limits. We observe a correlation between Δ<em>r<sub>np</sub></em> of <sup>208</sup>Pb and L. We compute the equations of state for nucleonic matter under <em>β</em> - equilibrium conditions for proposed interactions. We also discuss in detail the effects of Δ<em>r<sub>np</sub></em> and <em>L</em> on nuclear matter and neutron star properties. Additionally, these interactions are utilized to explore the characteristics of rotating neutron stars.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123307"},"PeriodicalIF":2.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.nuclphysa.2025.123311
P. Buganu , R. Budaca
The Bohr-Mottelson Hamiltonian, with an octic potential in the β deformation variable, is numerically solved for a γ-unstable symmetry of the nuclear system. The analytical structure of the model allows the description of multiple phenomena of great interest for the nuclear structure such as ground-state shape phase transitions and their critical points, dynamical shape phase transitions, shape coexistence with and without mixing, anomalous in-band E2 transitions, large E2 intra-band transitions and large monopole transition between the first excited state and the ground state, respectively. As a first application of the present model is selected the Cd isotopic chain known in literature to manifest shape phase transition, respectively shape coexistence and mixing.
{"title":"Bohr-Mottelson Hamiltonian with octic potential applied to the 106−116Cd isotopes","authors":"P. Buganu , R. Budaca","doi":"10.1016/j.nuclphysa.2025.123311","DOIUrl":"10.1016/j.nuclphysa.2025.123311","url":null,"abstract":"<div><div>The Bohr-Mottelson Hamiltonian, with an octic potential in the <em>β</em> deformation variable, is numerically solved for a <em>γ</em>-unstable symmetry of the nuclear system. The analytical structure of the model allows the description of multiple phenomena of great interest for the nuclear structure such as ground-state shape phase transitions and their critical points, dynamical shape phase transitions, shape coexistence with and without mixing, anomalous in-band <em>E</em>2 transitions, large <em>E</em>2 intra-band transitions and large monopole transition between the first excited <span><math><msup><mn>0</mn><mo>+</mo></msup></math></span> state and the ground state, respectively. As a first application of the present model is selected the <span><math><msup><mrow></mrow><mrow><mn>106</mn><mo>−</mo><mn>116</mn></mrow></msup></math></span>Cd isotopic chain known in literature to manifest shape phase transition, respectively shape coexistence and mixing.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123311"},"PeriodicalIF":2.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.nuclphysa.2025.123312
Mahima Upadhyay , Punit Dubey , Mahesh Choudhary , Namrata Singh , Shweta Singh , Sriya Paul , G. Mishra , G. Mohanto , Sukanya De , L.S. Danu , B. Lalremruata , Yu N. Kopatch , I.N. Ruskov , Ajay Kumar , R.G. Thomas , A. Kumar
The current study presents the cross-section measurement of 181Ta(n,γ)182Ta reaction at 1.37 ± 0.13, 2.06 ± 0.14, 2.56 ± 0.15, and 3.05 ± 0.17 MeV neutron energies utilizing offline γ-ray spectroscopy. The neutrons were generated through the 7Li(p,n)7Be reaction. The 115In(n,n’γ)115mIn reaction served as a monitor reaction. The present study provides detailed information on the propagation of uncertainty in the overall result. The required corrections for low energy background neutron and γ-ray coincidence summing effect have been made in the present measurement. The output is compared with the pre-existing cross-section data from the EXFOR database, evaluated data libraries and theoretical model predictions like level density models and γ-ray strength functions.
{"title":"Cross-section measurement of 181Ta(n,γ)182Ta with covariance analysis","authors":"Mahima Upadhyay , Punit Dubey , Mahesh Choudhary , Namrata Singh , Shweta Singh , Sriya Paul , G. Mishra , G. Mohanto , Sukanya De , L.S. Danu , B. Lalremruata , Yu N. Kopatch , I.N. Ruskov , Ajay Kumar , R.G. Thomas , A. Kumar","doi":"10.1016/j.nuclphysa.2025.123312","DOIUrl":"10.1016/j.nuclphysa.2025.123312","url":null,"abstract":"<div><div>The current study presents the cross-section measurement of <sup>181</sup>Ta(n,<em>γ</em>)<sup>182</sup>Ta reaction at 1.37 ± 0.13, 2.06 ± 0.14, 2.56 ± 0.15, and 3.05 ± 0.17 MeV neutron energies utilizing offline <em>γ</em>-ray spectroscopy. The neutrons were generated through the <sup>7</sup>Li(p,n)<sup>7</sup>Be reaction. The <sup>115</sup>In(n,n’<em>γ</em>)<sup>115<em>m</em></sup>In reaction served as a monitor reaction. The present study provides detailed information on the propagation of uncertainty in the overall result. The required corrections for low energy background neutron and <em>γ</em>-ray coincidence summing effect have been made in the present measurement. The output is compared with the pre-existing cross-section data from the EXFOR database, evaluated data libraries and theoretical model predictions like level density models and <em>γ</em>-ray strength functions.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123312"},"PeriodicalIF":2.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.nuclphysa.2025.123309
V. Parvathi, A. K. Rhine Kumar
Collective enhancement in nuclear level density (CELD) is a key phenomenon in the calculation of nuclear level density (NLD) arising from the coupling of intrinsic excitations with collective rotational and vibrational modes. This effect is especially pronounced in well-deformed nuclei, where rotational motion significantly increases the density of states at low excitation energies. However, increasing excitation energy leads to a gradual fadeout of this enhancement. In this study, we investigate CELD and its fadeout in the 169Tm nucleus, using the Finite-Temperature BCS (FTBCS) approach to calculate the intrinsic level density and incorporating rotational effects through a deformation-dependent enhancement factor. By examining free energy surfaces and shape transitions across different excitation energies and angular momenta, we aim to investigate the relationship between nuclear deformation and the emergence or suppression of collective effects. The results provide a comprehensive understanding of how shape evolution influences CELD behaviour in excited nuclear systems. However, the theoretically predicted fadeout energy is significantly higher than the experimentally observed value.
{"title":"Collective enhancement in nuclear level density and shape transitions in 169Tm","authors":"V. Parvathi, A. K. Rhine Kumar","doi":"10.1016/j.nuclphysa.2025.123309","DOIUrl":"10.1016/j.nuclphysa.2025.123309","url":null,"abstract":"<div><div>Collective enhancement in nuclear level density (CELD) is a key phenomenon in the calculation of nuclear level density (NLD) arising from the coupling of intrinsic excitations with collective rotational and vibrational modes. This effect is especially pronounced in well-deformed nuclei, where rotational motion significantly increases the density of states at low excitation energies. However, increasing excitation energy leads to a gradual fadeout of this enhancement. In this study, we investigate CELD and its fadeout in the <sup>169</sup>Tm nucleus, using the Finite-Temperature BCS (FTBCS) approach to calculate the intrinsic level density and incorporating rotational effects through a deformation-dependent enhancement factor. By examining free energy surfaces and shape transitions across different excitation energies and angular momenta, we aim to investigate the relationship between nuclear deformation and the emergence or suppression of collective effects. The results provide a comprehensive understanding of how shape evolution influences CELD behaviour in excited nuclear systems. However, the theoretically predicted fadeout energy is significantly higher than the experimentally observed value.</div></div>","PeriodicalId":19246,"journal":{"name":"Nuclear Physics A","volume":"1067 ","pages":"Article 123309"},"PeriodicalIF":2.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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