Radial Flow in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Au</mml:mi><mml:mi /><mml:mo>+</mml:mo><mml:mi /><mml:mi>Au</mml:mi></mml:math>Collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">E</mml:mi><mml:mi /><mml:mo>=</mml:mo><mml:mspace /><mml:mo>(</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:mn>2</mml:mn><mml:mn>5</mml:mn><mml:mo>−</mml:mo><mml:mn>1</mml:mn><mml:mo>.</mml:mo><mml:mn>1</mml:mn><mml:m

Lisa, M. A.; Albergo, S.; Bieser, F.; Brady, F.P.; Caccia, Z.; Cebra, D.; Chacon, A. D.; Chance, J. L.; Choi, Y.; Costa, S.; Elliott, J. B.; Gilkes, M. L.; Hauger, J. A.; Hirsch, A. S.; Hjort, E.; Insolia, A.; Justice, M.; Keane, D.; Kintner, J. C.; Matis, H. S.; McMahan, M. A.; McParland, C.; Olson, D.; Partlan, M. D.; Porile, N.; Potenza, R.; Rai, G.; Rasmussen, J. O.; Ritter, H. G.; Romański, J.; Romero, J. L.; Russo, G.; Scharenberg, R. P.; Scott, A.; Shao, Y.; Srivastava, B.; Symons, T. J. M.; Tincknell, M.; Tuvé, C.; Wang, S.; Warren, P.; Westfall, G. D.; Wieman, H.; Wolf, K.

doi:10.1103/physrevlett.75.2662

Cited by 93 publications

(68 citation statements)

References 29 publications

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“…1 shows that the events selected under the E RAT > 1.4 condition exhibit, in a representation of rapidity versus transverse momentum, a nearly isotropic source for the observed hydrogen (Z = 1) products. This is in agreement with previous observations [5][6][7]13].…”

supporting

confidence: 94%

Isospin Tracing: A Probe of Nonequilibrium in Central Heavy-Ion Collisions

Rami¹,

Leifels²,

Schauenburg³

et al. 2000

Phys. Rev. Lett.

137

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Four different combinations of 9644 Ru and 96 40 Zr nuclei, both as projectile and target, were investigated at the same bombarding energy of 400A MeV using a 4π detector. The degree of isospin mixing between projectile and target nucleons is mapped across a large portion of the phase space using two different isospin-tracer observables, the number of measured protons and the t/ 3 He yield ratio. The experimental results show that the global equilibrium is not reached even in the most central collisions. Quantitative measures of stopping and mixing are extracted from the data. They are found to exhibit a quite strong sensitivity to the in-medium (n,n) cross section used in microscopic transport calculations.PACS numbers: 25.75.Dw; 25.75.Ld Central heavy-ion collisions represent a valuable tool for studies of hot and dense nuclear matter where one hopes to infer valuable information on the nuclear equation of state (EOS) and on modifications of hadrons in the nuclear medium. It is still an open question whether the widely applied, at least local if not global, equilibrium assumption is valid in such reactions [1,2], or whether significant non-equilibrium effects rather require the application of more elaborated non-equilibrium dynamical models [2][3][4]. The issue of equilibration is expected to be influenced by in-medium effects (such as Pauli blocking, Fermi motion) on the 'hard' scattering processes, by early 'soft' deflections in the momentum-dependent mean fields, and by finite-size (corona) effects. An understanding of all these effects is a prerequisite for a quantitative extraction of the EOS from nucleus-nucleus collisions.Experimental observations of non-equilibrium in relativistic heavy-ion collisions were concentrated, up to now, on the measurement of the momentum distribution of the products emerging from a mid-rapidity "source" of symmetric colliding systems. Observables of interest were the width of rapidity distributions [3,5] or the overall shape of the source [6,7]. The sensitivity of such observables is however reduced by effects like rescattering during the late phase of expansion.In order to extract, in a model independent approach, direct experimental information on non-equilibrium we have designed a new type of high precision measurement which makes use of the isospin (N/Z) degree of freedom. The (N/Z) equilibration has been investigated before at low bombarding energies in fusion-like reactions [8][9][10]. As it will be shown in some details later, (N/Z) can be used as a tracer in order to attribute the measured nucleons (on average) either to the target or to the projectile nucleons. It is therefore possible to extract rapiditydensity distributions separately for projectile and target nucleons. This gives access to new more sensitive observables, like stopping and mixing, of the early equilibration process.The experiment was carried-out using reactions between equal mass nuclei A = 96, at an incident energy of 400A MeV. Isotopes of Ru and Zr were taken as projectile and target making ...

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supporting

confidence: 94%

Isospin Tracing: A Probe of Nonequilibrium in Central Heavy-Ion Collisions

Rami¹,

Leifels²,

Schauenburg³

et al. 2000

Phys. Rev. Lett.

137

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“…The freeze-out temperatures of (1232), produced in Ni + Ni collisions at 1-2A GeV and Au + Au collisions at 1.06A GeV, were extracted in Refs. [33,34] from the radial flow analysis. Further, in Ref.…”

Section: The Kinematical Spectra Of 0 (1232)mentioning

confidence: 99%

Δ0(1232) production ind+
Olimov
¹
,
Haseeb
²
,
Khan
³

et al. 2012
Phys. Rev. C
28
2
5
0
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Production of 0 (1232) resonances in d + 12 C collisions at 4.2A GeV/c was investigated with 4π acceptance, for the first time. The mass distribution of 0 (1232) resonances produced in d + 12 C collisions was reconstructed and their mass and width were extracted. The kinematical distributions of 0 (1232) were reconstructed in the laboratory frame and the corresponding mean kinematical characteristics were estimated. The fraction of charged π − mesons coming from 0 (1232) decay as well as the relative number of nucleons excited to 0 (1232) in freeze-out conditions were estimated. The freeze-out temperature of 0 (1232) was estimated and compared to results of other experiments with different sets of colliding nuclei and various incident energies.

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“…The β t value of the different experiments have been determined differently and in addition the impact parameter cut is different. The difference between the data of [7] and of [8] is not understood yet. We observe that the simulations follow very closely the experimental data.…”

mentioning

confidence: 99%

“…v t (A) is the mean transverse velocity of fragments with the mass number A. We made two fits in order to be comparable with the two sets of experiments [7,8] : one which includes all masses up to ten and a second where only masses smaller than five are included. The β t value of the different experiments have been determined differently and in addition the impact parameter cut is different.…”

mentioning

confidence: 99%

Transverse flow of nuclear matter in collisions of heavy nuclei at intermediate energies

Hartnack

Aichelin

2001

Physics Letters B

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The Quantum Molecular Dynamics Model (IQMD) is used to investigate the origin of the collective transverse velocity observed in heavy ion experiments. We find that there are three contributions to this effect: initial-final state correlations, potential interactions and collisions. For a given nuclear equation of state (eos) the increase of the transverse velocity with increasing beam energy is caused by the potential part. For a given beam energy the collective transverse velocity is independent of the nuclear eos but the relative contributions of potential and collisions differ. In view of the importance of the potential interactions between the nucleons it is not evident that the similarity of the radial velocities measured for fragments at beam energies below 1 AGeV and that for mesons at beam energies above 2 AGeV is more than accidental.A major goal of heavy ion collision studies is to extend our knowledge of the properties of dense and hot nuclear matter. In the past these studies were concentrated on the production of secondary particles like pions or kaons and on anisotropies in the momentum distribution like the directed in-plane flow (bounce-off) or the out of plane flow (squeeze-out) [1,2] of nuclear matter. For recent reviews of the different collective flows we refer to [3,4] Recently also the isotropic radial flow has gained large interest because at AGS and at CERN energies the existing data at mid-rapidity of most of the mesons and baryons can be well described by the assumption that the system is thermalized and expands with a collective velocity [5,6]. Later a similar observation has been made at energies between 150A MeV and 1A GeV (see eg. [7] - [10]). There the fragments, observed at mid-rapidity, show an energy which increases linearly with the fragment mass. At these low energies most of the pions come from the decay of nuclear resonances and therefore cannot be used to determine a transverse velocity and kaons are too rare to be of use for a such an analysis.The radial flow velocity β t determined with help of the fragment kinetic energies up to 1A GeV smoothly joints that determined with help of mesons and baryons starting from 11A GeV. This raised the question whether both transverse collective flows have a common origin and whether their functional dependence on the beam energy allows for conclusions about a possible transition between hadronic matter and a quark gluon plasma.A common origin of the transverse flow of fragments and mesons is not at all evident. Nucleons which are bound asymptotically in fragments do usually not suffer collisions with a large momentum transfer, otherwise they are not bound anymore. On the contrary, the creation of mesons requires a large momentum transfer.At beam energies below 1AGeV the radial flow seems to be a good candidate for measuring the nuclear equation of state. Increasing compression leads to an increasing pressure which is released isotropically. The directed transverse flow in the reaction plane, which in principle also depends on the press...

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Radial Flow inAu+AuCollisions atE=(0.25−1.1

Cited by 93 publications

References 29 publications

Isospin Tracing: A Probe of Nonequilibrium in Central Heavy-Ion Collisions

Isospin Tracing: A Probe of Nonequilibrium in Central Heavy-Ion Collisions

Δ0(1232) production ind+
Olimov
¹
,
Haseeb
²
,
Khan
³

et al. 2012
Phys. Rev. C
28
2
5
0
View full text Add to dashboard Cite

Transverse flow of nuclear matter in collisions of heavy nuclei at intermediate energies

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Radial Flow inAu+AuCollisions atE=(0.25−1.1

Cited by 93 publications

References 29 publications

Isospin Tracing: A Probe of Nonequilibrium in Central Heavy-Ion Collisions

Isospin Tracing: A Probe of Nonequilibrium in Central Heavy-Ion Collisions

Δ0(1232) production ind+Olimov1, Haseeb2, Khan3 et al. 2012Phys. Rev. C28250View full textAdd to dashboardCite

Transverse flow of nuclear matter in collisions of heavy nuclei at intermediate energies

Contact Info

Product

Resources

About

Δ0(1232) production ind+
Olimov
¹
,
Haseeb
²
,
Khan
³

et al. 2012
Phys. Rev. C
28
2
5
0
View full text Add to dashboard Cite