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Tōke, J.; Lott, B.; Baldwin, S. P.; Quednau, B.; Schröder, W.; Sobotka, L. G.; Barreto, J.; Charity, R. J.; Sarantites, D. G.; Stracener, D. W.; Souza, R. T. de

doi:10.1103/physrevlett.75.2920

Cited by 107 publications

(63 citation statements)

References 26 publications

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“…From in-plane fragment angular distribution a decrease of scission-to-scission lifetimes with the mass asymmetry of the P LF/T LF "fission-fragments" from 3000f m/c down to 200f m/c was deduced. Similar conclusions were reached in [179]. Consistent with the dynamical scenario was the anisotropic azimuthal distribution of IMF's.…”

Section: Isospin Dynamics For Neck Fragmentation In Semiperipheral Cosupporting

confidence: 77%

Reaction dynamics with exotic nuclei

et al. 2005

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Iste magistrorum locus est simul et puerorum, mittunt quando volunt hic res quas perdere nolunt [1]. AbstractWe review the new possibilities offered by the reaction dynamics of asymmetric heavy ion collisions, using stable and unstable beams. We show that it represents a rather unique tool to probe regions of highly Asymmetric Nuclear Matter (AN M ) in compressed as well as dilute phases, and to test the in-medium isovector interaction for high momentum nucleons. The focus is on a detailed study of the symmetry term of the nuclear Equation of State (EOS) in regions far away from saturation conditions but always under laboratory controlled conditions. Thermodynamic properties of AN M are surveyed starting from nonrelativistic and relativistic effective interactions. In the relativistic case the role of the isovector scalar δ-meson is stressed. The qualitative new features of the liquid-gas phase transition, "diffusive" instability and isospin distillation, are discussed. The results of ab-initio simulations of n-rich, n-poor, heavy ion collisions, using stochastic isospin dependent transport equations, are analysed as a function of beam energy and centrality. The isospin dynamics plays an important role in all steps of the reaction, from prompt nucleon emissions to the final fragments. The isospin diffusion is also of large interest, due to the interplay of asymmetry and density gradients. In relativistic collisions, the possibility of a direct study of the covariant structure of the effective nucleon interaction is shown. Results are discussed for particle production, collective flows and iso-transparency.Perspectives of further developments of the field, in theory as well as in experiment, are presented.

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Section: Isospin Dynamics For Neck Fragmentation In Semiperipheral Cosupporting

confidence: 77%

Reaction dynamics with exotic nuclei

et al. 2005

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“…Unfortunately, the decay pattern is also very sensitive to the dynamics of the excitation process, especially when collective degrees of freedom like rotation, shape distortion, and compression are strongly induced. These may have to be envisaged in the most often used [1][2][3] heavy-ion reactions. This ambiguity makes it difficult to correlate the observed decay pattern with either thermally or dynamically induced decay.…”

mentioning

confidence: 99%

Heating of Nuclei with Energetic Antiprotons

Goldenbaum¹,

Bohne²,

Eades³

et al. 1996

Phys. Rev. Lett.

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The annihilation of energetic (1.2 GeV) antiprotons is exploited to deposit maximum thermal excitation (up to 1000 MeV) in massive nuclei (Cu, Ho, Au, and U) while minimizing the contribution from collective excitation such as rotation, shape distortion, and compression. Excitation energy distributions ds͞dE ‫ء‬ are deduced from eventwise observation of the whole nuclear evaporation chain with two 4p detectors for neutrons and charged particles. The nuclei produced in this way are found to decay predominantly statistically, i.e., by evaporation.[ S0031-9007(96) The study of such decay modes of very highly excited nuclei as fission, multifragmentation, cracking, and vaporization is presently a major objective in nuclear physics because of its bearing on the lesser-known bulk properties of hot nuclear matter, such as heat capacity, specific heat, viscosity, and phase transitions. Unfortunately, the decay pattern is also very sensitive to the dynamics of the excitation process, especially when collective degrees of freedom like rotation, shape distortion, and compression are strongly induced. These may have to be envisaged in the most often used [1-3] heavy-ion reactions. This ambiguity makes it difficult to correlate the observed decay pattern with either thermally or dynamically induced decay.In order to minimize the influence of the entrance channel on the decay modes, we have, for the first time, investigated the nuclear excitation following annihilation of energetic antiprotons. Antiprotons annihilate on a single nucleon at the surface of, or even inside the nucleus, thereby producing a pion cloud containing an average of about 5 particles. Because of the high centerof-mass velocity (b c.m.0.63) of this cloud, it is focused forward into the nucleus. Since the pion momenta are comparable to the Fermi momentum of the nucleons in the nucleus, the pions heat the nucleus in a soft radiationlike way [4], probably even softer and more efficient than can be expected in proton-or other lightion-induced spallation reactions, which have also been exploited recently for this purpose [5][6][7].Intranuclear cascade (INC) calculations have been found to provide a reasonable description of this mechanism. They predict that the spin remains low (below maximum 25h) and that shape distortion and density compression are negligible [8], in contrast to what is expected in heavy-ion reactions. The reaction time for achievement of equilibrium conditions is only about 30 fm͞c or 10 222 s [9], which is much shorter in general than the dynamical period in heavy-ion reactions [10]. This is all the more important at high temperature (T ഠ 6 MeV) when the characteristic evaporation time reduces to t , 10 222 s, implying little cooling of the compound nucleus during heating.In this Letter we concentrate on the use of a new method to determine the thermal excitation energy produced with energetic antiprotons. This method is based on the eventwise observation of the whole nuclear evaporation chain, including both neutrons and charged particles...

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“…Naturally, simulation results are only approximate. For example, BUU simulations fail to describe the energy and angular distribution of neutrons and protons in low and mid energy domain [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Midrapidity charge distribution in peripheral heavy ion collisions

et al. 2001

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The charge density distribution with respect to the velocity of matter produced in peripheral heavy ion reactions around Fermi energy is investigated. The experimental finding of enhancement of midrapidity matter shows the necessity to include correlations beyond BUU which was performed in the framework of nonlocal kinetic theory. Different theoretical improvements are discussed. While the in-medium cross section changes the number of collisions, it leaves the transferred energy almost unchanged. In contrast the nonlocal scenario changes the energy transferred during collisions and leads to an enhancement of mid-rapidity matter. The renormalisation of quasiparticle energies can be included in nonlocal scenarios and leads to a further enhancement of mid-rapidity matter distribution. This renormalisation is accompanied by a dynamical softening of the equation of state seen in longer oscillation periods of the excited compressional collective mode. We propose to include quasiparticle renormalisation by using the Pauli-rejected collisions which circumvent the problem of backflows in Landau theory. Using the maximum relative velocity of projectile and target like fragments we associate experimental events with impact parameters of the simulations. For peripheral collisions we find a reasonable agreement between experiment and theory. For more central collisions, the velocity damping is higher in one-body simulations than observed experimentally, because of missing cluster formations in the kinetic theory used.

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Intermediate-Mass Fragment Decay of the Neck Zone Formed in Peripheral209Bi+136XeCollisions at
J. Tōke
¹
,
B. Lott
²
,
S. P. Baldwin
³

et al.

Cited by 107 publications

References 26 publications

Reaction dynamics with exotic nuclei

Reaction dynamics with exotic nuclei

Heating of Nuclei with Energetic Antiprotons

Midrapidity charge distribution in peripheral heavy ion collisions

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Intermediate-Mass Fragment Decay of the Neck Zone Formed in Peripheral209Bi+136XeCollisions atJ. Tōke1, B. Lott2, S. P. Baldwin3 et al.

Cited by 107 publications

References 26 publications

Reaction dynamics with exotic nuclei

Reaction dynamics with exotic nuclei

Heating of Nuclei with Energetic Antiprotons

Midrapidity charge distribution in peripheral heavy ion collisions

Contact Info

Product

Resources

About

Intermediate-Mass Fragment Decay of the Neck Zone Formed in Peripheral209Bi+136XeCollisions at
J. Tōke
¹
,
B. Lott
²
,
S. P. Baldwin
³

et al.