Transfer reaction study of neutron rich beryllium isotopes

The experimental study of exotic nuclei plays an important part in the understanding of nuclear structure. This thesis describes an experimental study of $^{10,11,12}$Be, three beryllium isotopes situated on the neutron rich side of the nuclear chart. The three isotopes were studied in direct reactions (scattering and transfer) using a low energy $^{11}$Be beam incident on a deuteron target. The aim of the experiment was to study the breaking of the N=8 magic number occurring in $^{12}$Be. The breaking is caused by the mixing of the 0p$_{1/2}$ and the 1s$_{1/2}$0d$_{5/2}$ shells. The mixing is also known to occur in $^{11}$Be, but the strength of the mixing in $^{12}$Be is still to be determined. The mixing can be determined by deriving the spectroscopic factors from direct reactions. The thesis will start with a description of the beryllium isotopes and an introduction to direct reactions including the definition of the spectroscopic factors. The experimental data analysed in this thesis stem from an experiment performed in September 2010 at the radioactive ion beam facility, ISOLDE, situated at CERN, Switzerland. The experiment was the third and last experiment in a series of $^{11}$Be+d experiments performed at ISOLDE. The first two experiments were performed in 2005 and 2009. The statistics in the first two experiments are significant lower than the statistic of the 2010 experiment and the first two experiments acted as preparation for the final experiment. The analysis of the two first experiments were performed from august 2008 to august 2010 and corresponds to the work done in the first two years of my PhD. The analysis formed the basis of my Part-A exam and will not be described in this thesis (the results can be found in 3 and 4 in the list of publications). The analysis, described in this thesis, can be divided into three parts the initial part, the main part, and a more detailed analysis of the data. Information regarding the experimental setup is determined in the initial part. This part contains calibration of the detectors and determining their individual positions, but also a calculation of the beam structure. The differential cross sections and spectroscopic factors are determined in themain part of the analysis. The last part of the analysis shows the strength of the setup by providing extra information about the three isotopes through a more detailed analysis.