Momentum dependent Vlasov-Uehling-Uhlenbeck calculation of mass dependence of the flow disappearance in heavy-ion collisions

Zhou, Huairong; Li, Zhuxia; Ye, Zhuo

doi:10.1103/physrevc.50.r2664

Cited by 22 publications

(35 citation statements)

References 19 publications

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“…It is worth mentioning that most of the earlier mass dependence calculations [7,10,21] could not reproduce the experimentally extracted slopes [7,10]. Zhou et al [21] could reproduce the slope, however their analysis was only done for lighter nuclei ≤ 200. Our calculations can reproduce the experimentally extracted slope very closely, therefore, we can predict the energy of vanishing flow in the 238 U + 238 U system.…”

Section: Coul Imentioning

confidence: 97%

Study of balance energy in central collisions for heavier nuclei

2004

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) is obtained in all cases. Our results are in excellent agreement with experimental data which allows us to predict the balance energy for 238 U + 238 U collision around 37-39 MeV/nucleon. PACS numbers:Thirty years ago it was predicted by Scheid and Greiner [1] that in heavy ion reactions the nuclei will be compressed and heated and that this yields for non central reactions to in-plane flow p dir x . More than a decade later, this conjecture was confirmed by the Plastic Ball group [2]. In the following investigations it turned out that this in-plane flow carries information on the nuclear equation of state [3]. If the nuclear equation of state is stiffer, more compressional energy will be stored in semicentral reactions and, when released, more in-plane flow will be given to the nucleons.The maximal density which is reached in a reaction depends on the beam energy as well as on the system size. The lower the beam energy the less is the compression. At very low energies, the repulsive part of the nuclear equation of state, which appears at densities above the normal nuclear matter density, is not tested anymore and the nucleons feel only the attractive mean field. A typical example is the deep inelastic reactions in which the two nuclei rotate around a common center. This rotation creates in-plane flow as well but in opposite direction: Due to the common rotation the nucleons stick together for a while and will be emitted into the direction opposite to the impact parameter whereas the in-plane flow which is caused by compression will be in the direction of the impact parameter.There is a beam energy at which the in-plane flow disappears when changing from the direction into that opposite to the impact parameter. It has been shown in the simulation of heavy ion reactions that this beam energy called balance energy, E bal , [4,5,6] depends on the nucleon-nucleon (nn) cross-section in the medium as well as on the potential [5,6] [7,12,13,15].Apart from the directed in-plane flow, differential as well as elliptic flow has also been predicted very recently [16].The measurements of the balance energy over wide range of system sizes provide an excellent opportunity to pin down the role of the mass dependence, where only preliminary studies [7,10] have been performed yet. These preliminary studies suggest a power law dependence ∝ A τ of the balance energy on the mass number of the system. Interestingly, most of the theoretical studies are done within the Boltzmann-Uehling-Uhlenbeck (BUU) model [4,5,6,7,10,12,15,16,17,18,19,20,21]. Some attempts, however, also exist within the framework of Quantum Molecular Dynamics (QMD) model [13,22,23,24]. Heavy systems are rather rarely analyzed in these approaches.Our present aim is therefore to study the mass dependence of the balance energy in heavy colliding nuclei and to predict for the first time the disappearance of the collective in-plane flow in central 238 U + 238 U collision. We shall show that the mass dependence of E bal for heavier nuclei scales approximately more asra...

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Section: Coul Imentioning

confidence: 97%

Study of balance energy in central collisions for heavier nuclei

2004

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“…Up to now, one has measured the energy of vanishing flow in the reactions of 12 C+ 12 C [3], 20 Ne+ 27 Al [3], 36 Ar+ 27 Al [6,7], 40 Ar+ 27 Al [8], 40 Ar+ 45 Sc [3,5,9], 40 Ar+ 51 V [10], 64 Zn+ 27 Al [11], 40 Ar+ 58 Ni [4], 64 Zn+ 48 Ti [7], 58 Ni+ 58 Ni [4,5,12], 58 Fe+ 58 Fe [12], 64 Zn+ 58 Ni [7], 86 Kr+ 93 Nb [3,5], 93 Nb+ 93 Nb [13], 129 Xe+ 118 Sn [4], 139 La+ 139 La [13], and 197 Au+ 197 Au [5,14,15]. A power law mass dependence of the energy of vanishing flow has also been reported in theoretical [3,5,12,14,18,22] as well as in experimental studies [3,5,12,14]. Looking at these mass dependence analyses, one observes that the power law behaviour reported for the mass dependence is not absolute, instead, it explains an average general trend of the mass dependence [3,5,12,14,18,22].…”

Section: Introductionmentioning

confidence: 95%

Systematic study of the energy of vanishing flow: Role of equations of state and cross sections

Sood

Puri

2006

Phys. Rev. C

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We present a systematic study of the energy of vanishing flow by considering symmetric colliding nuclei (between 12 C and 238 U) at normalized impact parameters using variety of equations of state (with and without momentum dependent interactions) as well as different nucleon-nucleon cross sections. A perfect power law mass dependence is obtained in all the cases which passes through calculated points nicely. Further, the choice of impact parameter affects the energy of vanishing flow drastically, demanding a very accurate measurement of the impact parameter. However, the energy of vanishing flow is less sensitive towards the equation of state as well as its momentum dependence.

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“…While a considerable progress [1][2][3][4][5] including that in subthreshold kaon production which provides complementary information on the EOS [6] has been reached in determining the EoS at supranormal densities, relying on reaction data, the uncertainties are still very large. To access the EoS, it is necessary to describe reaction observables [3][4][5], such as those quantifying the collective motion of nuclear matter, within reaction theory [1,2,[7][8][9][10][11]. The transport models employed in the description of central reactions have included the quantum molecular dynamics approaches in its QMD [12,13] and ImQMD [14][15][16] (with Im for Improved) variants, as well as the Boltzmann-Uehling-Uhlenbeck (BUU) approaches [17][18][19].…”

mentioning

confidence: 99%

In-mediumNNcross sections determined from the nuclear stopping and collective flow in heavy-ion collisions at intermediate energies

Zhang

Danielewicz

2007

Phys. Rev. C

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In-medium nucleon-nucleon scattering cross sections are explored by comparing results of quantum molecular dynamics simulations to data on stopping and on elliptic and directed flow in intermediate-energy heavy-ion collisions. The comparison points to in-medium cross sections which are suppressed at low energies but not at higher energies. Positive correlations are found between the degree of stopping and the magnitudes of elliptic and directed flows.

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Momentum dependent Vlasov-Uehling-Uhlenbeck calculation of mass dependence of the flow disappearance in heavy-ion collisions

Cited by 22 publications

References 19 publications

Study of balance energy in central collisions for heavier nuclei

Study of balance energy in central collisions for heavier nuclei

Systematic study of the energy of vanishing flow: Role of equations of state and cross sections

In-mediumNNcross sections determined from the nuclear stopping and collective flow in heavy-ion collisions at intermediate energies

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