Exclusive studies of neutron and charged particle emission in collisions of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Au</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>197</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mo>+</mml:mo></mml:mrow><

Leifels, Y.; Blaich, Th.; Elze, T.W.; Emling, H.; Freiesleben, H.; Grimm, K.; Henning, W.; Holzmann, R.; Jg, Keller; Klingler, H.; Jv, Kratz; Kulessa, R.; Lambrecht, Daniel S.; Lange, Stefan; Lubkiewicz, E.; Ef, Moore; Prokopowicz, W.; Schmidt, R.; Schütter, C.; Spies, Hans-Friedrich; Stelzer, K.; Stroth, J.; Wajda, E.; Waluś, W.; Zinser, M.; Zude, E.

doi:10.1103/physrevlett.71.963

Cited by 99 publications

(52 citation statements)

References 6 publications

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“…By excluding spectator neutrons [8] emitted from the projectile and the target, neutrons evaporated [33,34] from an excited projectile at small polar angles (θ ≤ 8 • ) were excluded also. Squeeze out of neutrons was observed previously [14] for Au-Au collisions at 400A MeV.…”

Section: Neutron Squeeze Outsupporting

confidence: 59%

“…Figure 7 shows the neutron triple-differential cross sections for the mid-rapidity bin at one of the polar angles (viz., θ = 48 • ) for La-La and Nb-Nb collisions at 400A MeV and La-La collisions at 250A MeV. In this bin, the neutrons are aligned perpendicular to the reaction plane at (φ − φ R ) = ±90 • (so called squeeze-out) [11,12,14]; however, this effect is barely noticeable in our figures. Rotating the event onto the flow axis enhances our ability to see the squeeze-out effect [11,32].…”

Section: A Neutron Triple-differential Cross Sectionsmentioning

confidence: 93%

“…The EOS is the relationship between density, temperature, and pressure for nuclear matter [1][2][3][4]. Various experiments [5][6][7][8][9][10][11][12][13][14][15] have been undertaken in an effort to extract the EOS. In central collisions, the overlap regions of the target and the projectile form a compression zone of high density.…”

Section: Introductionmentioning

confidence: 99%

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Neutrons from multiplicity-selected La-La and Nb-Nb collisions at400A MeVand La-La collisions at250A MeV

et al. 1999

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Triple-differential cross sections for neutrons from high-multiplicity La-La collisions at 250 and 400 MeV per nucleon and Nb-Nb collisions at 400 MeV per nucleon were measured at several polar angles as a function of the azimuthal angle with respect to the reaction plane of the collision. The reaction plane was determined by a transverse-velocity method with the capability of identifying charged-particles with Z = 1, Z = 2, and Z > 2. The flow of neutrons was extracted from the slope at mid-rapidity of the curve of the average in-plane momentum vs the center-of-mass rapidity. The squeeze-out of the participant neutrons was observed in a direction normal to the reaction plane in the normalized momentum coordinates in the center-of-mass system. Experimental results of the neutron squeeze-out were compared with BUU calculations. The polar-angle dependence of the maximum azimuthal anisotropy ratio r(θ) was found to be insensitive to the mass of the colliding nuclei and the beam energy. Comparison of the observed polar-angle dependence of the maximum azimuthal anisotropy ratio r(θ) with BUU calculations for free neutrons revealed that r(θ) is insensitive also to the incompressibility modulus in the nuclear equation of state.PACS numbers: 25.75+r, 25.75.Ld, 21.65.+f

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Section: Neutron Squeeze Outsupporting

confidence: 59%

Section: A Neutron Triple-differential Cross Sectionsmentioning

confidence: 93%

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Neutrons from multiplicity-selected La-La and Nb-Nb collisions at400A MeVand La-La collisions at250A MeV

et al. 1999

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“…Experiments at LBL/SIS have established the azimuthally anisotropic emission of particles from the reaction zone of two colliding nuclei: the directed flow of nucleons in the reaction plane ("side splash") and the preferred emission of nucleons perpendicular to the reaction plane ("squeeze-out") [86,87,88,89,90,91,92]. A collective out-of-plane emission was predicted by early hydrodynamical calculations and interpreted as a dynamical squeeze out of matter due to the build-up of pressure in the interaction zone [2].…”

Section: Angular Distributionsmentioning

confidence: 99%

Hadronic particle production in nucleus-nucleus collisions

Senger¹,

Ströbele

1999

J. Phys. G: Nucl. Part. Phys.

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Data on hadronic particle production in symmetric nuclear collisions from SIS/BEVALAC to SPS energies are reviewed. The main emphasis is put on the production of pions, kaons, and antibaryons. Global features will be discussed in terms of rapidity and transverse momentum distributions and the total energy stored in produced particles. Pion and kaon production probabilities are studied as function of beam energy and their distribution in polar and azimuthal angle. Special emphasis is put on medium effects expected for kaons in dense nuclear matter at low energies. An enhanced strange particle yield is found at all energies, its explanation at SPS energies is still controversial. Experimental data on antibaryon and multistrange hyperon production is less complete and does not allow for similar systematic studies.

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“…An alternative method is suggested by the results of Figure 3, demonstrating the sensitivity of E bal of neutron-rich particles, especially of the neutron. Measurements of neutron flows have been performed [42,43] and also the simultaneous measurement of neutron and proton flows are feasible [42,44]. In a very recent experiment at the GSI laboratory, an experiment aiming at the determination of directed and elliptic flows of neutrons and light charged particles with isotopic resolution up to Z 4 has been carried out for several systems at an incident energy of 400 MeV/nucleon [45].…”

Section: Resultsmentioning

confidence: 99%

Influence of the symmetry energy on the balance energy of the directed flow

Guo

Wang

Qing-feng

et al. 2012

Sci. China Phys. Mech. Astron.

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The influence of the density-dependent symmetry energy on the balance energy (E bal ) of directed flow from heavy ion collisions (HICs) at incident energies covered by INDRA and MSU experiments is studied, using the updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, especially adapted to low-energy heavy ion collisions (HICs). Four mass-symmetric reactions with total mass numbers between 192 and 394 are chosen for investigating the influence of the symmetry energy on the system-mass dependence of E bal . The results show that the uncertainty in the density dependence of the symmetry potential causes changes of E bal of the order of several MeV, depending on the type of particle considered. The E bal of neutrons from HICs is particularly sensitive to the density dependence of the symmetry potential energy, while the system-mass dependence of E bal of Z = 1 particles is not. symmetry energy, directed flow, balance energy PACS number(s): 21.65.Ef, 25.70.-z, 25.75.Ld Citation:A key objective in the study of heavy ion collisions (HICs), whether using stable or unstable beams, is to collect information about the nuclear equation of state (EoS). For stable nuclei with large mass numbers, the iso-vector part of the EoS is of importance due to the fact of their neutron number N being considerably larger than their proton number Z. Even for initially isospin-symmetric systems, the isospin effect should be taken into account since isospin diffusion and distillation may occur during the non-equilibrium stages of HICs. Essentially the whole collision is an isospin non-equilibrium process [1,2]. It is also well known and quite obvious that the isospin asymmetric EoS, besides in nuclear physics, is very important for understanding many phenomena in astrophysics as, e.g., the physics of neutron stars. At present, the *Corresponding author (email: liqf@hutc.zj.cn) largest uncertainty in the EoS is believed to come mainly from the density-dependent iso-vector part, the symmetry energy. For the isoscalar part, a soft EoS with incompressibility K around 230 MeV has been extracted through comparisons with data [3,4]. Significant progress in constraining the symmetry energy has been made during the past few years. For recent reviews we refer the reader to refs. [5,6]. Despite these achievements, the density dependence of the symmetry energy, especially at supranormal densities, is still not well determined due to strong model dependences [7][8][9][10].To reduce the model influence and to provide additional constraints, more isospin-related observables will have to be put forward, with the aim of arriving at a more authentic final form of the density-dependent symmetry energy. Besides the sensitive observables being studied up to now by several theoretical groups in this field (Please see the review article [5]

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Exclusive studies of neutron and charged particle emission in collisions ofAu197+<

Cited by 99 publications

References 6 publications

Neutrons from multiplicity-selected La-La and Nb-Nb collisions at400A MeVand La-La collisions at250A MeV

Neutrons from multiplicity-selected La-La and Nb-Nb collisions at400A MeVand La-La collisions at250A MeV

Hadronic particle production in nucleus-nucleus collisions

Influence of the symmetry energy on the balance energy of the directed flow

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