Nuclear Theory·nucl-th

Tuesday·October 5, 2021

16 papers—8 primary·8 cross-listed

01
Monte Carlo simulations of {\gamma}-directional correlations and their application on FIFRELIN cascades
A. Chalil (1) · T. Materna (1) · O. Litaize (2) · A. Chebboubi (2) · F. Gunsing (1) ( (1) IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France (2) CEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, France)
Angular distribution and correlation measurements are an essential part in nuclear structure experiments, especially when spectroscopic information of a specific nucleus is unknown. In most cases, the experimental determination of the spins, parities of the studied nuclear states, as well as the possible mixing between two electric/magnetic multipoles of a transition are determined using angular correlation measurements. In this work, the full effect of directional {\gamma}-correlations is simulated, by using the formal theory of angular distributions. The density matrix formalism along with its multipole expansions called statistical tensors is employed, enabling to perform a full simulation of the angular correlation effects in a cascade of an arbitrary number of {\gamma} transitions. A triple {\gamma} angular correlation simulation is demonstrated for the first time. The present approach was coupled with the Monte Carlo code FIFRELIN, which can simulate the de-excitation of fission fragments or of excited nuclei after neutron capture. It provides a complete description of the spatial distributions of all the {\gamma} rays in the cascade, that can be used for simulation purposes in various applications both in nuclear and particle physics. The potential for a novel approach in data analysis of angular correlation measurements is discussed thoroughly.
nucl-thnucl-exEPJA(2022)·7 citations
02
Strangeness neutral equation of state with a critical point
Jamie M. Karthein🇺🇸 · Debora Mroczek🇺🇸 · Angel R. Nava Acuna🇺🇸 · Jacquelyn Noronha-Hostler🇩🇪 · Paolo Parotto🇺🇸 · Damien R. P. Price🇺🇸 · Claudia Ratti🇺🇸
We formulate a family of equations of state for Quantum Chromodynamics that exhibit critical features and obey the charge conservation conditions present in heavy-ion collisions (HICs). This construction utilizes the first-principle Lattice QCD (LQCD) results up to $O (μ_{B}^{4})$ by matching the Taylor coefficients at each order. The criticality of the equation of state (EoS) is implemented based on the well-established principle of universal scaling behavior, where QCD belongs to the 3D Ising Model universality class. The critical point can be placed in a range of temperature and baryonic chemical potential relevant for the Beam Energy Scan II at RHIC. Furthermore, the strength of the critical features can be varied as well. This flexibility is embedded in four free parameters, that could potentially be constrained by the experimental data. We will discuss the features and versatility of our EoS, as well as present the relevant thermodynamic quantities which are important for hydrodynamical simulations of HICs.
nucl-thhep-thPoS(2022)·2 citations
03
Single-particle and collective structures in neutron-rich Sr isotopes
Kamila Sieja🇫🇷
Neutron-rich Sr nuclei around N=60 exhibit a sudden shape transition from spherical ground state to strongly prolate-deformed. Recently, a lot of new insight into the structure of Sr isotopes in this region was gained through experimental studies of excited levels, transitions strengths and spectroscopic factors. In this work, a "classic" shell-model description of strontium isotopes from N=50 to N=58 is provided, using a natural valence space outside the 78Ni core. Both even-even and even-odd isotopes are adressed. In particular, spectroscopic factors are computed to shed more light on the structure of low-energy excitations and their evolution along the Sr chain. The origin of deformation at N=60 is commented in the context of the present and previous shell-model and Monte-Carlo shell-model calculations.
nucl-thUniverse(2022)·9 citations
04
Derivation of the M $_{n}$ /M $_{p}$ ratio in exotic nuclei
E. Khan🇫🇷
A generalized formula is provided, to calculate the M $_{n}$ /M $_{p}$ ratio of the multipole transition matrix elements, in the framework of the so-called phenomenological analysis. It takes into account the possible difference between the neutron and proton radii and diffuseness, which can occur, especially in exotic nuclei. The validity domain of the original Bernstein formula is discussed, in the case of the proton scattering probe at few tens of MeV. The largest discrepancies are obtained for very neutron-rich nuclei (N/Z $≳$ 1.6) or when the electromagnetic deformation parameter is larger than the proton scattering one. The reduction of the statistical error bars, and the study of very neutron-rich nuclei at facilities of exotic beams of new generation, should favor the use of the generalized Bernstein formula.
nucl-thnucl-exPRC(2022)·2 citations
05
Utilization of Event Shape in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
Ryan Milton🇺🇸 · Gang Wang🇺🇸 · Maria Sergeeva🇺🇸 · Shuzhe Shi🇨🇦 · Jinfeng Liao🇺🇸 · Huan Zhong Huang🇺🇸
The search for the chiral magnetic effect (CME) has been a subject of great interest in the field of high-energy heavy-ion collision physics, and various observables have been proposed to probe the CME. Experimental observables are often contaminated with background contributions arising from collective motions (specifically elliptic flow) of the collision system. We present a method study of event-shape engineering (ESE) that projects the CME-sensitive $γ_{112}$ correlator and its variations ( $γ_{132}$ and $γ_{123}$ ) to a class of events with minimal flow. We discuss the realization of the zero-flow mode, the sensitivity on the CME signal, and the corresponding statistical significance for Au+Au, Ru+Ru, and Zr+Zr collisions at $s_{NN} = 200$ GeV with a multiphase transport (AMPT) model, as well as a new event generator, Event-By-Event Anomalous-Viscous Fluid Dynamics (EBE-AVFD).
nucl-thhep-exnucl-exPRC(2021)·21 citations
06
Effective Field Theory analysis of $^{3}$ He- $α$ scattering data
Maheshwor Poudel · Daniel R. Phillips
We treat low-energy $^{3}$ He- $α$ elastic scattering in an Effective Field Theory (EFT) that exploits the separation of scales in this reaction. We compute the amplitude up to Next-to-Next-to-Leading Order (NNLO), developing a hierarchy of the effective-range parameters that contribute at various orders. We use the resulting formalism to analyze data for recent measurements at center-of-mass energies of 0.38-3.12 MeV using the SONIK gas target at TRIUMF as well as older data in this energy regime. We employ a likelihood function that incorporates the theoretical uncertainty due to truncation of the EFT and use Markov Chain Monte Carlo sampling to obtain the resulting posterior probability distribution. We find that the inclusion of a small amount of data on the analysing power $A_{y}$ is crucial to determine the sign of the p-wave splitting in such an analysis. The combination of $A_{y}$ and SONIK data constrains all effective-range parameters up to $O (p^{4})$ in both s- and p-waves quite well. The ANCs and s-wave scattering length are consistent with a recent EFT analysis of the capture reaction $^{3}$ He( $α$ , $γ$ ) $^{7}$ Be.
nucl-thJ.Phys.G(2022)·12 citations
07
Neutron star crustal properties from relativistic mean-field models and bulk parameters effects
M. Dutra · C. H. Lenzi · W. de Paula · O. Lourenço
We calculate crustal properties of neutron stars, namely, mass ( $M_{crust}$ ), radius ( $R_{crust}$ ) and fraction of moment of inertia ( $Δ I / I$ ) from parametrizations of hadronic relativistic mean-field (RMF) model consistent with symmetric and asymmetric nuclear matter constraints, as well as some stellar boundaries. We verify which one are also in agreement with restrictions of $Δ I / I ⩾ 1.4%$ and $Δ I / I ⩾ 7%$ related to the glitching mechanism observed in pulsars, such as the Vela one. The latter constraint explains the glitches phenomenon when entrainment effects are taken into account. Our findings indicate that these parametrizations pass in the glitching limit for a neutron star mass range of $M ⩽ 1.82 M_{⊙}$ ( $Δ I / I ⩾ 1.4%$ ), and $M ⩽ 1.16 M_{⊙}$ ( $Δ I / I ⩾ 7%$ ). We also investigate the influence of nuclear matter bulk parameters on crustal properties and find that symmetry energy is the quantity that produces the higher variations on $M_{crust}$ , $R_{crust}$ , and~ $Δ I / I$ . Based on the results, we construct a particular RMF parametrization able to satisfy $Δ I / I ⩾ 7%$ even at $M = 1.4 M_{⊙}$ , the mass value used to fit data from the softer component of the Vela pulsar X-ray spectrum. The model also presents compatibility with observational data from PSR J1614-2230, PSR J0348+0432, and MSP J0740+6620 pulsars, as well as, with data from the Neutron Star Interior Composition Explorer (NICER) mission.
nucl-thastro-ph.HEEPJA(2021)·5 citations
08
DREENA-A framework as a QGP tomography tool
Dusan Zigic🇷🇸 · Igor Salom🇷🇸 · Jussi Auvinen🇷🇸 · Pasi Huovinen🇷🇸 · Magdalena Djordjevic🇷🇸
We present a fully optimised framework DREENA-A based on a state-of-the-art energy loss model. The framework can include any, in principle arbitrary, temperature profile within the dynamical energy loss formalism. Thus, 'DREENA' stands for Dynamical Radiative and Elastic ENergy loss Approach, while 'A' stands for Adaptive. DREENA-A does not use fitting parameters within the energy loss model, allowing it to fully exploit differences in temperature profiles which are the only input in the framework. The framework applies to light and heavy flavor observables, different collision energies, and large and smaller systems. This, together with the ability to systematically compare data and predictions within the same formalism and parameter set, makes DREENA-A a unique multipurpose QGP tomography tool.
nucl-thhep-phFront.in Phys.(2022)·43 citations

Affiliations

first authorsco-authorsvia INSPIRE