Etude de la structure de noyaux riches en neutrons à l'aide de nouvelles sondes

Abstract : The aim of this work is the investigation of the structure of light neutron-rich nuclei using different experimental and theoretical probes.

In the first instance, a complete study of one neutron removal reactions on $^{12-15}$B, $^{14-18}$C, $^{17-21}$N, $^{19-23}$O and $^{22-25}$F including the measurement of momentum distributions and cross-sections on C and Ta targets, is presented.
Extended Glauber and Coulomb dissociation models coupled to large scale shell model calculations together with a new model based on the sudden approximation to calculate transverse distributions have been developed. The results of these calculations are in very good agreement with the data. Consequently spin-parity assignements have been proposed for $^{15}$B, $^{17}$C, $^{19-21}$N, $^{21,23}$O et $^{23-25}$F and conclusions reached regarding the use of such reactions as a spectroscopic tool.

The alpha particle momentum distributions and cross-section for the breakup of $^6$He on a proton target have also been measured. The results agree with theoretical predictions indicating the sensitivity of the momentum distribution to the $^6$He continuum structure.

An experiment to observe proton radiative capture on $^6$He at 40 MeV/nucleon has also been undertaken for the first time. The capture on $^6$He resulting in the formation of $^7$Li has been observed with a cross-section of 35 $\pm$ 2 $\mu$b and the photon angular distribution measured. Triple ($^6$Li, 30 and 3.5 MeV photons) and double ($^4$He, 27 MeV photons) coincidences have also been observed. Such observations may be interpreted as proton capture the three body subsystems of $^6$He of $^5$He and $^4$He or as capture on $^6$He to form resonances in $^7$Li. The observation of a small number of coincidences between deuterons and 22~MeV photons together with other experimental indications favour the first hypothesis.
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Nuclear Theory. Université de Caen, 2000. French


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Contributor : Emmanuel Sauvan <>
Submitted on : Monday, March 10, 2008 - 6:52:49 PM
Last modification on : Wednesday, January 28, 2015 - 11:06:02 AM

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E. Sauvan. Etude de la structure de noyaux riches en neutrons à l'aide de nouvelles sondes. Nuclear Theory. Université de Caen, 2000. French. <tel-00262097>

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