Determination Of Neutron Density Distribution In C Isotopes Using Total Reaction Cross Section Measurements

Nuclear radius and density distribution are the fundamental characteristics of a nucleus.They are of great important in understanding the internal structure of a nucleus as well as in validating of theoretical models.The study of nuclear radius will effectively promote the studies in chiral nucleon-nucleon force,three-body nucleon-nucleon interaction,even-odd effects,mean-field theory and dynamic models.Precise measurement of nuclear radius and density distribution,especially the neutron density distribution in neutron rich nuclei,will provide not only the powerful experimental evidence for neutron skin and halo structures,but also reliable experimental data for nuclei properties and nuclear equation of state studies.Nuclear radius and density distribution are extracted by measuring the reaction cross section sigma(?R),interaction section(?I)and charge change section sigma(?cc)in experiment.The nuclear reaction cross section at high energies are sensitive to the root mean square radii.On the other hand,the reaction cross section at low energies are more sensitive to the outer structure of a nucleus.Therefore,to determine the density distribution of neutron rich nuclei,one need to measure the reaction cross section precisely at low energies.The experimental methods commonly used in reaction cross section and interaction cross section measurements are transmission method(or attenuation method),angular distribution measurement method of elastic scattering,Si stack telescope method and 4?-? coincident measurement.The existing cross section data of carbon isotope are mainly concentrated in the high energy region.Due to the lack of low energy cross section data or the cross section data at low energies with large errors,the density distribution extracted in C isotopes are still with large uncertainty.The experiment in this thesis was performed in the EN course terminator in the Research Center of Nuclear Physics(RCNP)at Osaka University.In cooperation with Tanihata's group at RCNP,we measured the reaction cross section in a transmission method using 45 A Me V 9-12 Be,8,10-15 B and 10-18 C beams irradiating a natC target.The reaction cross sections of these isotopes were measured in transmission method.The ?E-TOF-B? method were used to identify the beam particles before the target,while a multi-sampling ionization chamber(MUSIC)coupled with Na I(Tl)detector to form a telescope were arranged to measure the outgoing particles after the target.In this thesis,the reaction cross sections of 10-17 C were analyzed.Together with the existing cross section data,the neutron density distributions of 10-17 C were extracted by using the Glauber model calculations.The measured reaction cross sections are 1073 ± 19 mb,1107 ± 13 mb(37Me V/nucleon),1137 ± 14 mb,1258 ± 63 mb,1242 ± 20 mb,1603 ± 72 mb,1284 ± 32 mb and 1317 ± 21 mb for 10-17 C,respectively.Adopting the existing 12 C density distribution from the electron and ? scattering experiments,the force range parameter,r0 in Glauber model was determined for different beam energies.The neutron density distributions of 10-17 C were determined from the reaction cross sections at different energies and the root-mean-square radii of neutron and matter density distributions were also extracted.