Hunting Tools Beyond the Driplines

Doktorsavhandling, 2010

An important and growing sub-field of modern subatomic physics is the study of exotic isotopes using radioactive beams. Experiments started out simple, but are becoming more and more advanced. The increased complexity makes the use of software at all levels, from data acquisition to analysis, evermore present. However, it is rather the vast amounts of data collected in each experiment, than the sophistication of the calculations needed, that mandates the use of computers. This thesis describes methods to unpack and handle raw data acquired in nuclear physics experiments, and discusses the importance of transparency in the data formats to allow access to the information also after long times. The major part of the work has been performed at the ALADiN-LAND setup at GSI, in conjunction with experiments studying halo nuclei. Aspects of data collection and issues related to network-based event-building are discussed and resolved. It outlines a possible mechanism extending the existing MBS data acquisition system to allow injection of persistent slow-control information, stored along with the events. At the detector level, it discusses the calibration and reconstruction of a device where the digitised signals need multiple levels of transformations before the physical interactions are recovered. Moving outwards to the level of analysing data for the entire setup, an ongoing work to develop an experiment-independent scheme for tracking of particles in a barely overdetermined setup is described. Experimental findings for the very exotic He-9,10 and Li-12,13 systems beyond the dripline are shown, where Li-12,13 have been observed for the first time in this experiment. The intriguing results obtained earlier at the same facility for He-7 showing initially a weakening of the spin-orbit splitting have been reexamined using additional experimental information.