Nuclear Physics A最新文献

英文中文

Absorption of ψ(2S) mesons in nuclei

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-03-13 DOI: 10.1016/j.nuclphysa.2025.123069

E.Ya. Paryev

In the present work we explore the inclusive

ψ (2 S)

meson photoproduction from nuclei near the kinematic threshold within the collision model, based on the nuclear spectral function, for incoherent direct photon–nucleon charmonium creation processes. The model takes into account the final

ψ (2 S)

absorption, target nucleon binding and Fermi motion. We calculate the absolute and relative excitation functions for production of

ψ (2 S)

mesons on ¹²C and ¹⁸⁴ W target nuclei at near-threshold photon beam energies of 8.0–16.4 GeV, the absolute momentum differential cross sections for their production off these target nuclei at laboratory polar angles of 0^∘–10^∘, the momentum dependence of the ratio of these cross sections as well as the A-dependences of the ratios (transparency ratios) of the total cross sections for

ψ (2 S)

production at photon energy of 13 GeV within the different scenarios for the

ψ (2 S) N

absorption cross section. We also calculate the A-dependence of the ratio of

ψ (2 S)

and

J / ψ

photoproduction transparency ratios at photon energies around of 11.5 GeV within the adopted scenarios for this cross section. We demonstrate that both the absolute and relative observables considered reveal a definite sensitivity to these scenarios. Therefore, the measurement of such observables in future experiments at the upgraded up to 22 GeV CEBAF facility in the near-threshold energy region might shed light both on the

ψ (2 S) N

absorption cross section and on its part associated with the nondiagonal process

ψ (2 S) + N \to J / ψ + N

at finite momenta, which are of crucial importance in understanding of charmonium production and suppression in high-energy nucleus–nucleus collisions in a search for the quark-gluon plasma.

在本研究中，我们基于核光谱函数，在非相干直接光子-核子粲创造过程的碰撞模型中，探索了运动阈值附近核子的包容性ψ(2S)介子光生成。该模型考虑了最终的ψ(2S)吸收、靶核子结合和费米运动。我们计算了 12C 和 184 W 靶核在近阈值光子束能量 8.0-16.4GeV，在实验室极角为0∘-10∘的条件下从这些靶核上产生ψ(2S)介子的绝对动量差分截面，这些截面的比值与动量的关系，以及在光子能量为13 GeV时在ψ(2S)N吸收截面的不同情况下产生ψ(2S)介子的总截面的比值（透明度比）与A的关系。我们还计算了ψ(2S)和J/ψ光生成透明度比在光子能量为11.5 GeV左右时，在该截面所采用的方案中的A依赖性。我们证明，所考虑的绝对和相对观测值都显示出对这些方案的明确敏感性。因此，在未来升级到 22 GeV 的 CEBAF 设备上，在近阈值能量区域测量这些观测值，可能会揭示ψ(2S)N 吸收截面及其在有限时刻与非对角过程ψ(2S)+N→J/ψ+N 相关的部分、这对于理解高能核-核碰撞中粲的产生和抑制以及寻找夸克-胶子等离子体至关重要。

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引用次数: 0

High-energy Coulomb scattering of spatially extended particles

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-03-07 DOI: 10.1016/j.nuclphysa.2025.123068

M.L. Nekrasov

We analyze pure Coulomb high-energy elastic scattering of charged particles (hadrons or nuclei), discarding their strong interactions. We distinguish three scattering modes, determined by the magnitude of the momentum transfer, in which particles behave as point-like, structureless extended, and structured composite objects. The results are compared in the potential and QFT approaches of the eikonal model. In the case of proton Coulomb scattering at the LHC the difference between these two approaches is significant. This indicates the unsuitability of the potential approach. However, in the case of Coulomb scattering of heavy nuclei, the leading one is the optical approximation, which formally reproduces the prescription of the potential approach.

引用次数: 0

Triaxial shape evolution and shape coexistence in Radon isotopes within the covariant density functional theory

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-28 DOI: 10.1016/j.nuclphysa.2025.123059

H.M. Elsharkawy , M.M. Abdel Kader , A.M. Basha , A. Lotfy

The Covariant Density Functional Theory (CDFT) is utilized to systematically study the triaxial shape evolution of even-even radon isotopic chain (N=104-150) within the framework of the Relativistic Hartree-Bogoliubov (RHB) mean-field model. In the present work we make use of two distinct effective interactions: the Density-Dependent Meson-Exchange (DD-ME2) and the Density-Dependent Point-Coupling interaction with parameter set DD-PCX.

Neutron deficient side of the considered isotopic chain shows several shape coexistence states accompanied by little remarkable triaxial states appeared in that region. Various ground state properties, such as the binding energy per nucleon, the two-neutron separation energy, and the proton, neutron, and charge radii are also presented and compared with alternative theoretical approaches like the Deformed Relativistic Hartree–Bogoliubov theory in Continuum (DRHBc), the Finite-Range Droplet Model (FRDM), the Infinite Nuclear Matter Model (INMM) and the proxy-SU(3) model.

引用次数: 0

Advanced predictive modelling of electric quadrupole transitions in even-even nuclei using various machine learning approaches

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-23 DOI: 10.1016/j.nuclphysa.2025.123058

Sihem Berbache , Serkan Akkoyun , Ahmed H. Ali , Sebahattin Kartal

Empirical predictions of electric quadrupole transition probabilities, B (E2; 0⁺→2⁺), in even-even nuclei, are among the principles needed to solve the nuclear structure and collective behaviour. In this study, nine different ML algorithms, gradient boosting machine (GBM), random forest (RF), convolutional neural network (CNN), k-nearest neighbour (KNN), CatBoost, extreme gradient boosting (XGBoost), neural network (NN), support vector machine (SVM) and multiple linear regression (MLR), are evaluated as a different data-driven solution for the prediction of B(E2) values. The outcomes show that ensemble models, in particular GBMs, RF, and XGBoost, provide vastly improved predictive capabilities and generalizing influence while creating strong correlations to experimental data with small prediction errors. On the other hand, deep learning models such as CNN and NN is prone to overfitting, while simpler ones such as MLR and KNN fail to capture the non-linear relationships inherent in nuclear data. The findings underscore the promise of ensemble ML tools for nuclear physics in a scalable, accurate approach for predicting transition probabilities.

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引用次数: 0

Investigation of ground state and the β-decay properties of 156−162Nd

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-20 DOI: 10.1016/j.nuclphysa.2025.123057

Abdul Kabir , Jameel-Un Nabi , Noor-Ul Ain Raza , Hamad Almujibah

The nuclear ground state and beta decay properties for ^156−162Nd have been investigated within the framework of the relativistic mean field (RMF) approach and proton-neutron quasi-particles random phase approximation (pn-QRPA) model. The RMF model with density-dependent interactions DDME2 and DDPC1 is utilized to analyze the potential energy curves (PECs), potential energy surfaces (PESs), the nuclear ground state deformation parameter (

β_{2}

), neutron (proton) separation energies (S_n(S_p) and S

_{2 n}

_{2 p}

)), neutron skin thickness (r

_{n p}

), and root mean square radius (r

_{r m s}

). Furthermore, the

β_{2}

computed via the finite range droplet model (FRDM) and RMF with DDME2 and DDPC1-based interactions are employed in the pn-QRPA model as an input parameter for the calculations of the beta decay properties, including the Gamow Teller (GT) strength, log ft values, and half-lives of ^156−162Nd. The FRDM and RMF-DDPC1-based calculated log ft values show better consistency with the measured data. The present computed beta decay half-lives are in reasonable agreement with the experimental data.

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引用次数: 0

The effect of three-body nucleon-nucleon interaction on the ground state binding energy of the light nuclei

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-20 DOI: 10.1016/j.nuclphysa.2025.123056

F. Kamgar, G.H. Bordbar, S.M. Zebarjad, M.A. Rastkhadiv

<div><div>We calculate the ground state binding energies of the light nuclei such as <span><math><mmultiscripts><mrow><mi>H</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>4</mn></mrow></mmultiscripts><mi>e</mi></math></span>, <span><math><mmultiscripts><mrow><mi>L</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>6</mn></mrow></mmultiscripts><mi>i</mi></math></span>, <span><math><mmultiscripts><mrow><mi>C</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>12</mn></mrow></mmultiscripts></math></span> and <span><math><mmultiscripts><mrow><mi>N</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>14</mn></mrow></mmultiscripts></math></span> by considering the effect of three-body nucleon-nucleon interaction. We use the effective two-body potential obtained from the lowest order constrained variational (LOCV) calculations of the nuclear matter for the <span><math><mi>R</mi><mi>e</mi><mi>i</mi><mi>d</mi><mn>68</mn></math></span>, <span><math><mi>A</mi><msub><mrow><mi>V</mi></mrow><mrow><mn>14</mn></mrow></msub></math></span>, <span><math><mi>U</mi><msub><mrow><mi>V</mi></mrow><mrow><mn>14</mn></mrow></msub></math></span>, and <span><math><mi>A</mi><msub><mrow><mi>V</mi></mrow><mrow><mn>18</mn></mrow></msub></math></span> nuclear potentials in different channels. To calculate the ground state binding energy, we implement the local density approximation by using the harmonic oscillator wave functions while the effect of three-body interaction is considered by employing the UIX potential. We compare the obtained two-body ground state binding energy with the energy related to the three-body effect. We also compare the obtained values with the experimental data and also work of others, and show that the results are relatively acceptable. We compute the root mean-square radius <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>r</mi><mi>m</mi><mi>s</mi></mrow></msub></math></span> of the above nuclei for the <span><math><mi>R</mi><mi>e</mi><mi>i</mi><mi>d</mi><mn>68</mn></math></span>, <span><math><mi>A</mi><msub><mrow><mi>V</mi></mrow><mrow><mn>14</mn></mrow></msub></math></span>, <span><math><mi>U</mi><msub><mrow><mi>V</mi></mrow><mrow><mn>14</mn></mrow></msub></math></span>, and <span><math><mi>A</mi><msub><mrow><mi>V</mi></mrow><mrow><mn>18</mn></mrow></msub></math></span> potentials and compare the results with the experiment. We also obtain the contribution of different channels by matching to the experimental values of the quadrupole moments and magnetic dipole moments. Furthermore, we calculate the three-body cluster energy of the above nuclei and compare the results with that of nuclear matter. According to the obtained results, we see that the three-body cluster energy contribution is small. For example, for <span><math><mmultiscripts><mrow><mi>H</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>4</mn></mrow></mmultiscripts><mi>e</mi></math></span> nuclide, this value is 0.079 MeV with the <spa

引用次数: 0

Enhancing heavy ion accelerator capabilities in Australia

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-19 DOI: 10.1016/j.nuclphysa.2025.123036

M. Dasgupta, S. Battisson, L.T. Bezzina, D.J. Hinde, N.R. Lobanov, P. Linardakis, T.R. McGoram, C. Notthoff, E.C. Simpson, D. Tempra, T. Tunningley

Heavy Ion Accelerators is a network of ion accelerators in Australia, located in Canberra and Melbourne. The Heavy Ion Accelerators (HIA) network delivers ion-implantation capabilities and accelerated ion beams for a wide range of research and industrial applications including in nuclear, quantum, space, environmental and medical physics areas. Completed and planned enhancements to HIA capabilities are expanding the areas of applicability and strengthening Australia's training and research capabilities.

引用次数: 0

Estimating centrality in heavy-ion collisions using Transfer Learning technique

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-18 DOI: 10.1016/j.nuclphysa.2025.123043

Dipankar Basak , Kalyan Dey

In this study, we explore the applicability of Transfer Learning techniques for estimating collision centrality in terms of the number of participants (

N_{part}

) in high-energy heavy-ion collisions. In the present work, we leverage popular pre-trained CNN models such as VGG16, ResNet50, and DenseNet121 to determine

N_{part}

in Au+Au collisions at

\sqrt{s_{N N}} = 200

GeV on an event-by-event basis. Remarkably, all three models achieved good performance despite the pre-trained models being trained for databases of other domains. Particularly noteworthy is the superior performance of the VGG16 model, showcasing the potential of transfer learning techniques for extracting diverse observables from heavy-ion collision data.

引用次数: 0

Quasifission and deep inelastic collisions competing with superheavy element creation

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-17 DOI: 10.1016/j.nuclphysa.2025.123040

D.J. Hinde , D.Y. Jeung , M. Dasgupta , J. Buete , K.J. Cook , C. Simenel , E.C. Simpson , H.M. Albers , Ch.E. Düllmann , J. Khuyagbaatar , A. Yakushev

Fusion forming superheavy elements is strongly inhibited by the faster non-equilibrium Deep Inelastic (DIC) and quasifission processes. These have often been considered as distinct processes, but recent measurements for reactions involving heavy nuclei such as ²⁰⁸Pb and lighter suggest that these two processes form a continuum. However, for reactions of heavy ions with actinide nuclei, binary mass-split spectra show reduced yields for fragments lighter than the target, resulting in a peak in yield close to ²⁰⁸Pb. This gives an apparent separation between DIC and quasifission outcomes. The ²⁰⁸Pb peak has generally been attributed to the ²⁰⁸Pb closed shells giving a valley in the potential energy surface, attracting quasifission trajectories. However, recent extensive binary and three-body cross-sections extracted for reactions of ⁵⁰Ti with actinide nuclides could not be explained in this framework. Rather, the big drop in yield observed for the heavier actinide targets is consistent with sequential fission of heavy deep inelastic/quasifission fragments.

To search for shell effects in quasifission independent of sequential fission, systematics of mass spectra in non-actinide reactions forming actinide compound nuclei were studied. These showed negligible effects of the shells known to cause low energy mass-asymmetric fission of these nuclei. All these results raise questions over the understanding of the effects of closed shells on the quasifission mechanism, and quasifission mass distributions.

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引用次数: 0

The upgrade of the facility EXOTIC

IF 1.7 4区物理与天体物理 Q2 PHYSICS, NUCLEAR

Nuclear Physics A

Pub Date : 2025-02-17 DOI: 10.1016/j.nuclphysa.2025.123039

S. Pigliapoco , D. Brugnara , M. Mazzocco , J.J. Valiente-Dobon , P. Aguilera , G. Andreetta , F. Angelini , M. Balogh , D. Bazzacco , J. Benito Garcia , G. Benzoni , S. Bottoni , S. Carollo , S. Cherubini , M. Costa , F.C.L. Crespi , G. D'Agata , G. De Angelis , M. Del Fabbro , A. Di Pietro , L. Zago

With the installation of the γ-ray spectrometer AGATA at the Laboratori Nazionali di Legnaro (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN), the scientific activity with the Radioactive Ion Beam facility EXOTIC had to be temporarily suspended and the reaction chambers located at its final focal plane had to be removed. In this period of forced inactivity, we reorganized all the services, upgraded all control systems of the facility and developed a new event-by-event tracking system based on MicroChannelPlate (MCP) detectors. These interventions are preparing the ground for coupling EXOTIC and AGATA to perform experiments exploiting the unique features provided by both equipments.

引用次数: 0

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Nuclear Physics A

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