Interactions of energetic gold nuclei in nuclear emulsions

Waddington, C. J.; Freier, P. S.

doi:10.1103/physrevc.31.888

Cited by 94 publications

(64 citation statements)

References 14 publications

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“…Campi has, for example, used experimental data for the extraction of the second moment [24,25]. Figure 2 shows that these quantities do indeed provide clear experimental signatures of the first-order transition in a finite-size system.…”

Section: First Order Phase Transition In Intermediate-energy Heavy Iomentioning

confidence: 99%

First-Order Phase Transition in Intermediate-Energy Heavy Ion Collisions

1998

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We model the disassembly of an excited nuclear system formed as a result of a heavy ion collision. We find that, as the beam energy in central collisions in varied, the dissociating system crosses a liquidgas coexistence curve, resulting in a first-order phase transition. Accessible experimental signatures are identified: a peak in the specific heat, a power-law yield for composites, and a maximum in the second moment of the yield distribution. [S0031-9007(97) PACS numbers: 25.70. Pq, 21.65. + f, 24.10.Pa, 64.60.My Nuclear matter is a fictitious arbitrarily large N Z system in which the Coulomb interaction is switched off. Mean-field theory for nuclear matter has been applied many times, and it is well known that such a system shows a van-der-Waals-type liquid-gas phase transition. It was suggested in the early 1980s [1,2] that in heavy ion collisions at intermediate energies one might be able to probe this liquid-gas phase transition region. In heavy ion collisions, matter would be heated as well as compressed. This compressed blob would then expand passing through the liquid-gas coexistence phase. One might be able to extract information about this region from selected experimental data. Earlier, the Purdue group had conjectured that the breakup of large nuclei by energetic protons would show signatures of critical phenomena [2].There are several complications which make the study of phase transitions in nuclei difficult. The systems are small, thus singularities get replaced by broad peaks. The collision is over quickly. The existence of thermal equilibrium has sometimes been questioned and replaced by quite complicated transport equation approaches. Often one has been content to do calculations where the objective is to fit the experimental data. Once this is achieved the question of a possible liquid-gas phase transition is not addressed. There are models where such questions are irrelevant, or at least very indirect, such as various models based on sequential decays. The literature on calculations for fragment yields in intermediate energy heavy ion collisions is huge. We will not attempt to mention all approaches.In this paper we will focus on the liquid-gas phase transition using a lattice gas model [3]. Previously we have used the model to fit data on central collisions [3], on peripheral collisions [4], and for central Au on Au collisions [5]. The model gives a fair description of data in those instances-does it say anything definite about the experimental signature of liquid-gas phase transitions?In the lattice gas model we place n nucleons in N cubes, where n is the number of nucleons in the disassembling system, and N͞n r 0 ͞r f , where r 0 is the normal nuclear density, and the disassembly is to be calculated at r f , the "freeze-out" density beyond which nucleons are too far apart to interact. An attractive nearestneighbor interaction is assumed. We place the n nucleons in N cubes by Monte Carlo sampling using the Metropolis algorithm. Once the nucleons have been placed we also ascribe to each...

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Section: First Order Phase Transition In Intermediate-energy Heavy Iomentioning

confidence: 99%

First-Order Phase Transition in Intermediate-Energy Heavy Ion Collisions

1998

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“…In recent years it has become possible to do exclusive measurements of multifragmentation reactions. This has been done with streamer chamber detectors [33,34] or with electronic 4 n detectors [11, . With the availability of 4 n detectors it is possible to study the multifragment breakup of nuclear systems in much greater detail, due to the huge number of events which can be sampled.…”

Section: Introductionmentioning

confidence: 99%

Dynamical treatment of Fermi motion in a microscopic description of heavy ion collisions

et al. 1992

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A quasiclassical Pauli potential is used to simulate the Fermi motion of nucleons in a molecular dynamical simulation of heavy ion collisions. The thermostatic properties of a Fermi gas with and without interactions are presented. The inclusion of this Pauli potential into the quantum molecular dynamics (QMD) approach yields a model with well defined fermionic ground states, which is therefore also able to give the excitation energies of the emitted fragments. The deexcitation mechanisms (particle evaporation and multifragmentation) of the new model are investigated. The dynamics of the QMD with Pauli potential is tested by a wide range of comparisons of calculated and experimental doubledifferential Cross sections for inclusive p-induced reactions at incident energies of 80 to 160 MeV. Results at 256 and 800 MeV incident proton energy are presented as predictions for completed experiments which are as yet unpublished. PACS number(s): 24.10. Cn,

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“…Attempts have been made to study critical phenomena in nuclear emulsions under the assumption that the projectile fragmentation products can be isolated even in central collisions at 1A GeV [3] with some positive conclusions concerning a sharp phase transition [4]. Another attempt to use data from central collisions alone and assume initial fusion at energies between 20 A and 200 A MeV also indicates the onset of multifragmentation but not as a sharp transition [5].…”

Section: Introductionmentioning

confidence: 98%

28Si(32S) fragmentation at 3.7 A, 14.6 A and 200 A GeV

Adamovich¹,

Aggarwal²,

Alexandrov³

et al. 1995

Z. Physik A - Hadrons and Nuclei

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Abstract. The fragmentation topology of 28Si at 3.7A GeV and 14.6AGeV and 32S at 200AGeV in reactions with emulsion nuclei is presented. The fragmentation cross sections are very similar at all three energies. A statistical percolation model can qualitatively describe the data for Z >_ 6. The He production is underestimated and the 3 < Z < 5 fragments overestimated by this model. 20.25; 75. + r PCAS:

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Interactions of energetic gold nuclei in nuclear emulsions

Cited by 94 publications

References 14 publications

First-Order Phase Transition in Intermediate-Energy Heavy Ion Collisions

First-Order Phase Transition in Intermediate-Energy Heavy Ion Collisions

Dynamical treatment of Fermi motion in a microscopic description of heavy ion collisions

28Si(32S) fragmentation at 3.7 A, 14.6 A and 200 A GeV

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