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Flow and multifragmentation in nuclear collisions at intermediate energies

  • H. G. Ritter(corresponding author)
    ,
  • S. Albergo
    ,
  • F. Bieser
    ,
  • F. P. Brady
    ,
  • Z. Caccia
    ,
  • A. D. Chacon
*Corresponding author for this work
  • Lawrence Berkeley National Laboratory
    ,
  • University of Catania
    ,
  • University of California at Davis
    ,
  • Texas A&M University
    ,
  • Purdue University
    ,
  • Kent State University
Scholary Output:
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Article
Research
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Abstract

Energy spectra of hydrogen and helium isotopes emitted in Au+Au collisions at 0.25, 0.40, 0.60, 0.80, 1.0, and 1.15A GeV have been measured. A systematic study of the shapes of the spectra reveals a significant non-thermal component consistent with collective radial flow. The strength of this component is evaluated as a function of bombarding energy. Comparisons of the flow signal to predictions of QMD and BUU models are made. Using reverse kinematics, the breakup of gold nuclei has been studied in Au+C reactions at 1.0A GeV. The moments of the resulting charged fragment distribution provide evidence that nuclear matter possesses a critical point observable in finite nuclei. Values for the critical exponents γ, β, and τ have been determined. These values are close to those for liquid-gas systems and different from those for 3D percolation.

Publication Information

Output type

Scholary Output:
Contribution to journal
Article
Research
 Peer-review

Original language

English (US)

Pages from-to (Number of pages)

Pages 491-498 (8 pages)

Journal (Volume, Issue Number)

Nuclear Physics, Section A (Volume 583, Issue C)

Publication milestones

  • Published - 02/06/1995

Publication status

Published - 02/06/1995

ISSN

0375-9474

Publication IDs

  • Scopus: 4243842817

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Funding Details

I)etaih'd measm'ement and analysis of fragment emission ha.s led to new results in dif-frr~,nt areas, l,arge collective flow has been observed in several experiments. The EOS ,lal.a. show thal. the energy spectra of light particlesemitted at midrapidity in Au+Au collisions can 1)e well described in terms of a radially-expanding, thermal source with a co, unon (low and a common temperature parameter for deuterons, tritons, aHe, and c~ i~articles. Radial llow in central collisions increases as a function of bombarding energy. QMI) and I_{Ull model calculations reproduce the temperature and flow parameters sat-isfaetorily. Very little dependence of the radial flow strength on the equation of state is see, in Lhe rnode\]s. How accounts for about 50% of the energy of light particles en\]itted at, m idrapidity from central collisions at all bombarding energies. A detailed investigation of file Ih)w as a function of emission angle and impact parameter is under way \[15\]. \Ve ha.re analyzed the fragments emitted in Au+C reactions at 1.0A GeV with a tech- nique borrowed from percolation theory. The influence of finite size effects has been taken iuto a.ccou,lt by our procedure. We have been able to extract independently the values of three critical expouents from the data. These exponents are close to the values of the liquid-gas system. The analysis of systems of different size is in progress to further characterize this phenomenon. This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear l)hysics, Division of Nuclear Physics of the U.S. Department of Energy under C.ontracts I)I~-AC03-76SF00098, DE-FG02-89ER40531, DE-FG02-88ER40408, DEI"G02-88El{40412, I)E-I"G05-88ER40437, and by the National Science Foundation under (h'ant PHY-9123301.