Correlations between emission timescale of fragments and isospin dynamics in $^{124}$Sn+$^{64}$Ni and $^{112}$Sn+$^{58}$Ni reactions at 35 AMeV

Abstract : We present a new experimental method to correlate the isotopic composition of intermediate mass fragments (IMF) emitted at mid-rapidity in semi-peripheral collisions with the emission timescale: IMFs emitted in the early stage of the reaction show larger values of $<$N/Z$>$ isospin asymmetry, stronger angular anisotropies and reduced odd-even staggering effects in neutron to proton ratio $<$N/Z$>$ distributions than those produced in sequential statistical emission. All these effects support the concept of isospin "migration", that is sensitive to the density gradient between participant and quasi-spectator nuclear matter, in the so called neck fragmentation mechanism. By comparing the data to a Stochastic Mean Field (SMF) simulation we show that this method gives valuable constraints on the symmetry energy term of nuclear equation of state at subsaturation densities. An indication emerges for a linear density dependence of the symmetry energy.
docType_s : Journal articles
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http://hal.in2p3.fr/in2p3-00704236
Contributor : Lion Michel <>
Submitted on : Tuesday, June 5, 2012 - 9:00:10 AM
Last modification on : Tuesday, June 5, 2012 - 9:00:10 AM

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E. De Filippo, A. Pagano, P. Russotto, F. Amorini, A. Anzalone, et al.. Correlations between emission timescale of fragments and isospin dynamics in $^{124}$Sn+$^{64}$Ni and $^{112}$Sn+$^{58}$Ni reactions at 35 AMeV. Physical Review C, American Physical Society, 2012, 86, pp.014610. <10.1103/PhysRevC.86.014610>. <in2p3-00704236>

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