Physical Review C最新文献

{"title":"Reevaluation of the \u0000Ne22(α,γ)Mg26\u0000 and \u0000Ne22(α,n)Mg25\u0000 reaction rates","authors":"P. Adsley, U. Battino, A. Best, A. Caciolli, A. Guglielmetti, G. Imbriani, H. Jayatissa, M. La Cognata, L. Lamia, E. Masha, C. Massimi, S. Palmerini, A. Tattersall, R. Hirschi","doi":"10.1103/PHYSREVC.103.015805","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.015805","url":null,"abstract":"Background: The competing $^{22}mathrm{Ne}(ensuremath{alpha},ensuremath{gamma})^{26}mathrm{Mg}$ and $^{22}mathrm{Ne}(ensuremath{alpha},n)^{25}mathrm{Mg}$ reactions control the production of neutrons for the weak $s$ process in massive and asymptotic giant branch (AGB) stars. In both systems, the ratio between the corresponding reaction rates strongly impacts the total neutron budget and strongly influences the final nucleosynthesis. A number of experimental studies have been performed over recent years which necessitate the reevaluation of the $^{22}mathrm{Ne}(ensuremath{alpha},ensuremath{gamma})^{26}mathrm{Mg}$ and $^{22}mathrm{Ne}(ensuremath{alpha},n)^{25}mathrm{Mg}$ reaction rates. Evaluations of the reaction rates following the collection of new nuclear data presently show differences of up to a factor of 500, resulting in considerable uncertainty in the resulting nucleosynthesis.Purpose: To reevaluate the $^{22}mathrm{Ne}(ensuremath{alpha},ensuremath{gamma})^{26}mathrm{Mg}$ and $^{22}mathrm{Ne}(ensuremath{alpha},n)^{25}mathrm{Mg}$ reaction rates using updated nuclear data from a number of sources including updating spin and parity assignments.Methods: With updated spin and parity assignments, the levels which can contribute to the reaction rates are identified. The reaction rates are computed using a Monte Carlo method which has been used for previous evaluations of the reaction rates in order to focus solely on the changes due to modified nuclear data.Results: The evaluated $^{22}mathrm{Ne}(ensuremath{alpha},ensuremath{gamma})^{26}mathrm{Mg}$ reaction rate remains substantially similar to that of Longland et al. but, including recent results from Texas A, the $^{22}mathrm{Ne}(ensuremath{alpha},n)^{25}mathrm{Mg}$ reaction rate is lower at a range of astrophysically important temperatures. Stellar models computed with newton and mesa predict decreased production of the weak branch $s$ process due to the decreased efficiency of $^{22}mathrm{Ne}$ as a neutron source. Using the new reaction rates in the mesa model results in $^{96}mathrm{Zr}/^{94}mathrm{Zr}$ and $^{135}mathrm{Ba}/^{136}mathrm{Ba}$ ratios in much better agreement with the measured ratios from presolar SiC grains.Conclusion: The $^{22}mathrm{Ne}+phantom{rule{0.16em}{0ex}}ensuremath{alpha}$ reaction rates $^{22}mathrm{Ne}(ensuremath{alpha},ensuremath{gamma})^{26}mathrm{Mg}$ and $^{22}mathrm{Ne}(ensuremath{alpha}.n)^{25}mathrm{Mg}$ have been recalculated based on more recent nuclear data. The $^{22}mathrm{Ne}(ensuremath{alpha},ensuremath{gamma})^{26}mathrm{Mg}$ reaction rate remains substantially unchanged since the previous evaluation but the $^{22}mathrm{Ne}(ensuremath{alpha}.n)^{25}mathrm{Mg}$ reaction rate is substantially decreased due to updated nuclear data. This results in significant changes to the nucleosynthesis in the weak branch of the $s$ process.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"518 1","pages":"015805"},"PeriodicalIF":3.1,"publicationDate":"2021-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77169296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Fluid velocity from transverse momentum spectra","authors":"A. Guillen, J. Ollitrault","doi":"10.1103/PhysRevC.103.064911","DOIUrl":"https://doi.org/10.1103/PhysRevC.103.064911","url":null,"abstract":"We show that the momentum distributions calculated in ideal hydrodynamic simulations of nucleus-nucleus collisions are determined, to a good approximation, by the distribution of the transverse velocity of the fluid. We compute the fluid velocity distribution that gives the best fit to experimental data on Pb+Pb collisions at $sqrt{s_{rm NN}}=2.76$ TeV. We obtain reasonable fits up to $p_tsim 6$ GeV, much beyond the range where hydrodynamics is usually applied. However, the fit is not perfect, even at low $p_t$. We actually argue that an ideal hydrodynamic calculation cannot fit simultaneously all identified particle spectra, irrespective of the specific implementation. In particular, data display a significant excess of pions at low $p_t$, whose physical interpretation is discussed. Data also show that the distribution of the fluid velocity becomes broader as the collision becomes less central. This broadening is explained by event-by-event hydrodynamic calculations, where it results from the centrality dependence of initial state fluctuations.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"25 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81346291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Calculation of nuclear charge radii with a trained feed-forward neural network","authors":"Di Wu, C. Bai, H. Sagawa, H. Q. Zhang","doi":"10.1103/physrevc.102.054323","DOIUrl":"https://doi.org/10.1103/physrevc.102.054323","url":null,"abstract":"A feed-forward neural network model is trained to calculate the nuclear charge radii. The model is trained with the input data set of proton and neutron number Z,N, the electric quadrupole transition strength B(E2) from the first excited 2+ state to the ground state, together with the symmetry energy. The model reproduces well not only the isotope dependence of charge radii, but also the kinks of charge radii at the neutron magic numbers N=82 for Sn and Sm isotopes, and also N=126 for Pb isotopes. The important role of the B(E2) value is pointed out to reproduce the kink of the isotope dependence of charge radii in these nuclei. Moreover, with the inclusion of the symmetry energy term in the inputs, the charge radii of Ca isotopes are well reproduced. This result suggests a new correlation between the symmetry energy and charge radii of Ca isotopes. The Skyrme Hartree-Fock-Bogoliubov calculation is performed to confirm the existence of this correlation in a microscopic model.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"72 1","pages":"054323"},"PeriodicalIF":3.1,"publicationDate":"2020-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90604576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Strength of the isoscalar pairing interaction determined by a relation between double-charge change and double-pair transfer for double-\u0000β\u0000 decay","authors":"J. Terasaki","doi":"10.1103/physrevc.102.044303","DOIUrl":"https://doi.org/10.1103/physrevc.102.044303","url":null,"abstract":"","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"12 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2020-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75184361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Description of the low-lying collective states of \u0000Zr96\u0000 based on the collective Bohr Hamiltonian including the triaxiality degree of freedom","authors":"E. V. Mardyban, E. Kolganova, T. Shneidman, R. Jolos, N. Pietralla","doi":"10.1103/PHYSREVC.102.034308","DOIUrl":"https://doi.org/10.1103/PHYSREVC.102.034308","url":null,"abstract":"Background: Several collective low-lying states are observed in $^{96}mathrm{Zr}$ whose properties, which include excitation energies and $E2, E0$, and $M1$ transition probabilities, indicate that some of them belong to the spherical state and the other to deformed states. A consideration of these data in the full framework of the geometrical collective Model with both intrinsic shape variables, $ensuremath{beta}$ and $ensuremath{gamma}$, and rotational degrees of freedom is necessary for $^{96}mathrm{Zr}$.Purpose: We investigate the properties of the low-lying collective states of $^{96}mathrm{Zr}$ based on the five-dimensional geometrical collective model including triaxiality as an active degree of freedom.Method: The quadrupole-collective Bohr Hamiltonian, depending on both $ensuremath{beta}$ and $ensuremath{gamma}$ shape variables with a potential having spherical and deformed minima, is applied. The relative depth of two minima, height and width of the barrier, and rigidity of the potential near both minima are determined so as to achieve a satisfactory description of the observed properties of the low-lying collective quadrupole states of $^{96}mathrm{Zr}$.Results: It is shown that the low-energy structure of $^{96}mathrm{Zr}$ can be described in a satisfactory way within the geometrical collective model with a potential function supporting shape coexistence without other restrictions on its shape. It is shown that a correct determination of the $ensuremath{beta}$ dependence of the collective potential from the experimental data requires a consideration in the framework of the full Bohr collective Hamiltonian. It is shown also that the excitation energy of the ${2}_{2}^{+}$ state can be reproduced only if the rotation inertia coefficient is taken to be four times smaller than the vibrational one in the region of the deformed well. It is shown also that shell effects are important for the description of the $B(M1;{2}_{2}^{+}ensuremath{rightarrow}{2}_{1}^{+})$ and $B(M1;{3}_{1}^{+}ensuremath{rightarrow}{2}_{1}^{+})$ transition probabilities. An indication of the influence of the pairing vibrational mode on the ${0}_{2}^{+}ensuremath{rightarrow}{0}_{1}^{+}$ transition is confirmed, in agreement with the previous result.Conclusion: Qualitative agreement with the experimental data on the excitation energies and $B(E2)$ and $B(M1;{2}_{2}^{+}ensuremath{rightarrow}{2}_{1}^{+})$ reduced transition probabilities is obtained.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"67 1","pages":"034308"},"PeriodicalIF":3.1,"publicationDate":"2020-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89875179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Proton-number fluctuations in \u0000sNN=2.4 GeV Au + Au\u0000 collisions studied with the High-Acceptance DiElectron Spectrometer (HADES)","authors":"J. Adamczewski-Musch, O. Arnold, C. Behnke, A. Belounnas, A. Belyaev, J. Berger-Chen, A. Blanco, C. Blume, M. Böhmer, P. Bordalo, S. Chernenko, L. Chlad, I. Ciepał, C. Deveaux, J. Dreyer, E. Epple, L. Fabbietti, O. Fateev, P. Filip, P. Fonte, C. Franco, J. Friese, I. Fröhlich, T. Galatyuk, J. A. Garzón, R. Gernhäuser, M. Golubeva, R. Greifenhagen, F. Guber, M. Gumberidze, S. Harabasz, T. Heinz, T. Hennino, S. Hlavac, C. Höhne, R. Holzmann, A. Ierusalimov, A. Ivashkin, B. Kämpfer, T. Karavicheva, B. Kardan, I. Koenig, W. Koenig, M. Kohls, B. Kolb, G. Korcyl, G. Kornakov, F. Kornas, R. Kotte, A. Kugler, T. Kunz, A. Kurepin, A. Kurilkin, P. Kurilkin, V. Ladygin, R. Lalik, K. Lapidus, A. Lebedev, L. Lopes, M. Lorenz, T. Mahmoud, L. Maier, A. Malige, A. Mangiarotti, J. Markert, T. Matulewicz, S. Maurus, V. Metag, J. Michel, D. Mihaylov, S. Morozov, C. Müntz, R. Münzer, L. Naumann, K. Nowakowski, Y. Parpottas, V. Pechenov, O. Pechenova, O. Petukhov, K. Piasecki, J. Pietraszko, W. Przygoda, K. Pysz, S. Ramos, B.","doi":"10.1103/physrevc.102.024914","DOIUrl":"https://doi.org/10.1103/physrevc.102.024914","url":null,"abstract":"","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"356 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2020-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76502865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Hadronic effects on charmonium elliptic flows in heavy-ion collisions","authors":"Baoyi Chen, Liu Jiang, Yunpeng Liu","doi":"10.1103/PhysRevC.103.064910","DOIUrl":"https://doi.org/10.1103/PhysRevC.103.064910","url":null,"abstract":"We study the effects of hadron phase on the collective flows of charmonia in heavy-ion collisions. In Pb-Pb collisions, charmonia with high transverse momentum $p_T$ are produced by the primordial hard process and then travel through the hot dense medium. In the semi-central centrality, the anisotropic energy density of quark-gluon plasma (QGP) in the transverse plane is transformed to the momentum anisotropy of the hadrons after the phase transition. Charmonia suffer different magnitudes of dissociation along different paths in QGP and then scatter with light hadrons in the hadron phase. We calculate both contributions and find that hadronic interactions can significantly enhance the elliptic flows of charmonia especially the excited states in the high $p_T$, which will increase the elliptic flows of prompt and inclusive $J/psi$s with the decay process $chi_c( psi^prime)rightarrow J/psi$ X.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"46 2 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2020-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83891289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Multilayer neutron stars with scalar mesons crossing term","authors":"S. Kubis, W. W'ojcik, N. Zabari","doi":"10.1103/physrevc.102.065803","DOIUrl":"https://doi.org/10.1103/physrevc.102.065803","url":null,"abstract":"It is shown that recently proposed RMF model with $sigma$ and $delta$ meson interaction agrees with the observational data and presents an interesting structure with phase transition in the outer part of neutron star core.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"54 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84475899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Formation of superheavy nuclei in \u0000S36+U238\u0000 and \u0000Ni64+U238\u0000 reactions","authors":"V. L. Litnevsky, F. Ivanyuk, G. Kosenko, S. Chiba","doi":"10.1103/PHYSREVC.101.064616","DOIUrl":"https://doi.org/10.1103/PHYSREVC.101.064616","url":null,"abstract":"We describe the capture, fusion, fission, and evaporation residue formation cross sections of superheavy nuclei within the proposed earlier two-stage dynamical model. The approaching of the projectile nucleus to the target nucleus is described in the first stage of the model. In the second stage, the evolution of the system formed after the touching of the projectile and target nuclei is considered. The evolution of the system on both stages is described by the Langevin equations. The transport coefficients of these equations for the shape degrees of freedom are calculated within the microscopic linear-response theory. The mutual orientation of the colliding ions, the tunneling through the Coulomb barrier in the entrance channel and the shell effects in the potential energy on both stages of the calculations are taking into account. The obtained results are compared with the available experimental data and other theoretical predictions.","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"12 1","pages":"064616"},"PeriodicalIF":3.1,"publicationDate":"2020-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81783986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Reexamination of isoscalar giant resonances in \u0000C12\u0000 and \u0000Nb93\u0000 through \u0000Li6\u0000 scattering","authors":"J. C. Zamora, C. Sullivan, R. Zegers, N. Aoi, L. Batail, D. Bazin, M. Carpenter, J. Carroll, I. Deloncle, Y. Fang, H. Fujita, U. Garg, G. Gey, C. Guess, M. Harakeh, T. Hoang, E. Hudson, N. Ichige, E. Ideguchi, A. Inoue, J. Isaak, C. Iwamoto, C. Kacir, N. Kobayashi, T. Koike, M. Raju, S. Lipschutz, M. Liu, P. Neumann-Cosel, S. Noji, H. Ong, S. Péru, J. Pereira, J. Schmitt, A. Tamii, R. Titus, V. Werner, Y. Yamamoto, X. Zhou, Sutao Zhu","doi":"10.1103/physrevc.101.064609","DOIUrl":"https://doi.org/10.1103/physrevc.101.064609","url":null,"abstract":"","PeriodicalId":48700,"journal":{"name":"Physical Review C","volume":"195 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2020-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75902475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}