Étude des corrélations dans la dissociation de l'$^{8}$He

Abstract : Correlations in light neutron-rich nuclei are of considerable importance in understanding their structure. In this context the breakup of 8He into $^{6}$He+2n has been investigated at 15 MeV/nucleon. The measurements were undertaken using a setup composed of two detector arrays : CHARISSA to detect the charged fragments and DEMON to detect the neutrons. The interpretation of the results was facilitated using a Monte Carlo simulation which was developed to take into account the correlations, the reaction and the experimental setup.
Two techniques were used to study the correlations in the breakup of $^{8}$He. The first, intensity interferometry, provides, via the construction of the neutron-neutron correlation function, for a first estimate of the source size and thus the average separation between the neutrons. The second, using Dalitz plots, allows both the neutron-neutron and core-neutron correlations to be probed. Here, sequential decay via the ground state resonance of $^{7}$He and has been found to dominate the dissociation of $^{8}$He. The spatiotemporal characteristics of the breakup of 8He have thus been deduced and an RMS separation between the two
valence neutrons in the continuum states was estimated to be 7.3[=+]0.6 fm with a time delay between their emission of 1 000[=+]300 fm/c.
Document type :
Physique Nucléaire Théorique [nucl-th]. Université de Caen, 2007. Français

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  • HAL Id : tel-00265845, version 1



B. Laurent. Étude des corrélations dans la dissociation de l'$^{8}$He. Physique Nucléaire Théorique [nucl-th]. Université de Caen, 2007. Français. <tel-00265845>




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