Signals for a Transition from Surface to Bulk Emission in Thermal Multifragmentation

L. Beaulieu; T. Lefort; K. Kwiatkowski; R. T. de Souza; W.-c. Hsi; L. Pienkowski; B. Back; D. S. Bracken; H. Breuer; E. Cornell; F. Gimeno-Nogues; D. S. Ginger; S. Gushue; R. G. Korteling; R. Laforest; E. Martin; K. B. Morley; E. Ramakrishnan; L. P. Remsberg; D. Rowland; A. Ruangma; V. E. Viola; G. Wang; E. Winchester; S. J. Yennello

doi:10.1103/PhysRevLett.84.5971

Signals for a Transition from Surface to Bulk Emission in Thermal Multifragmentation

L. Beaulieu, T. Lefort, K. Kwiatkowski, R. T. de Souza, W.-c. Hsi, L. Pienkowski, B. Back, D. S. Bracken, H. Breuer, E. Cornell, F. Gimeno-Nogues, D. S. Ginger, S. Gushue, R. G. Korteling, R. Laforest, E. Martin, K. B. Morley, E. Ramakrishnan, L. P. Remsberg, D. Rowland, A. Ruangma, V. E. Viola, G. Wang, E. Winchester, and S. J. Yennello

Phys. Rev. Lett. 84, 5971 – Published 26 June 2000

Abstract

Excitation-energy-gated two-fragment correlation functions have been studied between $E^{*} / A = (2 - 9) A MeV$ for equilibriumlike sources formed in $8 - 10 GeV / c$ $π^{-}$ and ${p +}^{197} Au$ reactions. Comparison with an $N$ -body Coulomb-trajectory code shows an order of magnitude decrease in the fragment emission time in the interval $E^{*} / A = (2 - 5) A MeV$ , followed by a nearly constant breakup time at higher excitation energy. The decrease in emission time is strongly correlated with the onset of multifragmentation and thermally induced radial expansion, consistent with a transition from surface-dominated to bulk emission expected for spinodal decomposition.

Received 1 November 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.5971

Authors & Affiliations

L. Beaulieu¹, T. Lefort¹, K. Kwiatkowski^1,*, R. T. de Souza¹, W.-c. Hsi¹, L. Pienkowski², B. Back³, D. S. Bracken^1,†, H. Breuer⁴, E. Cornell^1,‡, F. Gimeno-Nogues⁵, D. S. Ginger^1,§, S. Gushue⁶, R. G. Korteling⁷, R. Laforest^5,∥, E. Martin⁵, K. B. Morley², E. Ramakrishnan⁵, L. P. Remsberg⁶, D. Rowland⁵, A. Ruangma⁵, V. E. Viola¹, G. Wang^1,¶, E. Winchester⁵, and S. J. Yennello⁵

¹Department of Chemistry and IUCF, Indiana University, Bloomington, Indiana 47405
²Heavy Ion Laboratory, Warsaw University, Warsaw, Poland
³Physics Division, Argonne National Laboratory, Argonne, Illinois 60439
⁴Department of Physics, University of Maryland, College Park, Maryland 20740
⁵Department of Chemistry & Cyclotron Laboratory, Texas A&M University, College Station, Texas 77843
⁶Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973
⁷Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A IS6

^*Present address: Los Alamos National Laboratory, Los Alamos, New Mexico 87545.
^†
^‡Present address: Lawrence Berkeley Laboratory, Berkeley, California 94720.
^§Present address: Cambridge University, Cambridge, United Kingdom.
^∥Present address: Barnes Hospital, Washington University, St. Louis, Missouri 63130.
^¶Present address: Epsilon, Inc., Dallas, Texas 75240.