Source shape determination with directional fragment–fragment velocity correlations

Rosato, E.; Vigilante, M.

doi:10.1016/j.physletb.2007.11.081

Cited by 5 publications

(5 citation statements)

References 42 publications

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“…For comparison to the symmetry energy predictions of the VEOS model we have derived symmetry energies from the ejectile yield data by employing an isoscaling analysis. Such analyses have been reported in a number of recent papers [10,11,27,28,29,30]. In this approach the yields of a particular species Y(N,Z) from two different equilibrated nuclear systems, 1 and 2, of similar temperature but different neutron to proton ratios, N/Z, are expected to be related through the isoscaling relationship…”

Section: Isoscalingmentioning

confidence: 95%

“…It is normally assumed that all contributions to F sym other than that arising from the symmetry energy, e.g. bulk, Coulomb and surface, may be ignored [10,11,27,28,29,30]. Most commonly, the expression,…”

Section: Isoscalingmentioning

confidence: 99%

“…in which γ is the symmetry energy coefficient, has been employed with estimates of Z 1 /A 1 , Z 2 /A 2 and T to obtain estimates of γ [10,11,27,28,29,30]. While the approximate equation 6 may be reasonable for systems near normal density, it becomes increasingly less accurate at low densities where entropic effects become increasingly more important [31].…”

Section: Isoscalingmentioning

confidence: 99%

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Experimental determination of the symmetry energy of a low density nuclear gas

et al. 2007

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Experimental analyses of moderate temperature nuclear gases produced in the violent collisions of 35 MeV/nucleon 64 Zn projectiles with 92 Mo and 197 Au target nuclei reveal a large degree of alpha particle clustering at low densities. For these gases, temperature and density dependent symmetry energy coefficients have been derived from isoscaling analyses of the yields of nuclei with A ≤ 4. At densities of 0.01 to 0.05 times the ground state density of symmetric nuclear matter, the temperature and density dependent symmetry energies range from 9.03 to 13.6 MeV. This is much larger than those obtained in mean field Calculations and reflects the clusterization of low density nuclear matter. He are expected to be small and they are ignored in the calculation. In the work reported in reference [1] these virial coefficients were then used to make predictions for a variety of properties of nuclear matter over a range of density, temperature and composition. The authors view this virial equation of state, derived from experimental observables, as modelindependent, and therefore a benchmark for all nuclear equations of state at low densities. Its importance in both nuclear physics and in the physics of the neutrino sphere in supernovae is discussed in the VEOS paper [1]. A particularly important feature of the VEOS, emphasized in reference [1], is the natural inclusion of clustering which leads to large symmetry energies at low baryon density.In this paper we extend our investigations of the nucleon and light cluster emission that occurs in near-Fermi energy heavy ion collisions [2,3,4,5,6] to investigate the properties of the low density participant matter produced in such collisions. The data provide experimental evidence for a large degree of alpha clustering in this low density matter, in agreement with theoretical predictions [1,7,8,9]. Temperature and density dependent symmetry free energies and symmetry energies have been determined at densities of 0.05ρ 0 or less, where ρ 0 is the ground state density of symmetric nuclear matter, by application of an isoscaling analysis [10,11]. The symmetry energy coefficient values obtained, 9.03 to 13.6 MeV, are much larger then those derived from effective interactions in mean field models. The values are in reasonable agreement with those calculated in the VEOS treatment of reference [1]. EXPERIMENTAL PROCEDURESThe reactions of 35A MeV 64 Zn projectiles with 92 Mo and 197 Au target nuclei were studied at the K-500 SuperConducting Cyclotron at Texas A&M University, using the 4π detector array NIMROD [3]. NIMROD consists of a 166 segment charged particle array set inside a neu-

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Section: Isoscalingmentioning

confidence: 95%

Section: Isoscalingmentioning

confidence: 99%

Section: Isoscalingmentioning

confidence: 99%

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Experimental determination of the symmetry energy of a low density nuclear gas

et al. 2007

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“…The fragment-fragment velocity correlations measured in Xe + Sn central collisions were used in Ref. [35] to extract the information of the deformed shape of the source. In Ref.…”

Section: Space-time Information From Correlationsmentioning

confidence: 99%

“…An important question is, however, whether such clusterized states are realized with correct probabilities during the time evolution of reactions. Under the equation of motion (35) with the usual stochastic two-nucleon collisions, the cluster correlation is governed by the classical phase space. Let us consider here the density of statesD( ) (or more precisely the difference of the density of states from that of the noninteracting system) for the internal state of an A c -nucleon cluster.…”

Section: Amd With Clustersmentioning

confidence: 99%

Dynamics of clusters and fragments in heavy-ion collisions

Ono

2019

Progress in Particle and Nuclear Physics

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A review is given on the studies of formation of light clusters and heavier fragments in heavy-ion collisions at incident energies from several tens of MeV/nucleon to several hundred MeV/nucleon, focusing on dynamical aspects and on microscopic theoretical descriptions. Existing experimental data already clarify basic characteristics of expanding and fragmenting systems typically in central collisions, where cluster correlations cannot be ignored. Cluster correlations appear almost everywhere in excited low-density nuclear many-body systems and nuclear matter in statistical equilibrium where the properties of a cluster may be influenced by the medium. On the other hand, transport models to solve the time evolution have been developed based on the single-nucleon distribution function. Different types of transport models are reviewed putting emphasis both on theoretical features and practical performances in the description of fragmentation. A key concept to distinguish different models is how to consistently handle single-nucleon motions in the mean field, fluctuation or branching induced by two-nucleon collisions, and localization of nucleons to form fragments and clusters. Some transport codes have been extended to treat light clusters explicitly. Results indicate that cluster correlations can have strong impacts on global collision dynamics and correlations between light clusters should also be taken into account.

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Particle-particle correlations: Femtoscopy and tools for spectroscopy

Verde

2012

EPJ Web of Conferences

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A review of particle-particle correlation studies at intermediate and medium energies is presented. The main results on space-time access to reaction dynamics are discussed with a look at future perspectives to obtain probes of the density dependence of the symmetry energy.Particle-particle correlations offer tools to study space-time properties in reaction dynamics [1] and certain spectroscopic information about unbound states [2,3]. On one hand the sensitivity to space-time properties of the reaction has led to an extensive use of intensity interferometry in nuclear reactions at both intermediate and relativistic energies [1,4]. On the other hand, if two or more particles can be detected as decay products of a specific unbound state produced during the reaction the measured correlation functions contain spectroscopic information about their parent unbound state. This has recently led to use correlations also as a tool for spectroscopy [2,3,5]. In this respect one can reasonably state that heavy-ion collisions and multi-particle correlations represent a rich laboratory to study nuclear systems.

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Source shape determination with directional fragment–fragment velocity correlations

Abstract: Correlation functions, constructed from directional projections of the relative velocities of fragments, are used to determine the shape of the breakup volume in

Cited by 5 publications

References 42 publications

Experimental determination of the symmetry energy of a low density nuclear gas

Experimental determination of the symmetry energy of a low density nuclear gas

Dynamics of clusters and fragments in heavy-ion collisions

Particle-particle correlations: Femtoscopy and tools for spectroscopy

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