Graduate Studies in Accelerator Physics

28° Cycle Graduate Students

OSCAR FRASCIELLO

PhD Activity

The research activity of Dr. Oscar Frasciello, during his first year of PhD studentship, was focused on the study and design of IR components for the LHC upgrade, from the Wakefields and Impedance point of view, after gaining a research grant in the framework of HiLumi-LHC project. He gained appropriate knowledge of GdfidL electromagnetic simulation code, characterizing present LHC secondary collimators geometry. He contributed significantly to the understanding of the discrepancy by a factor of two between the betatron tune shifts calculated with the "old" LHC impedance model and the experimentally measured ones, identifying in the geometric beam coupling impedance one of the major contributors to this discrepancy. So forth, the LHC impedance model was suitably updated. A detailed study was also driven on the impedance modeling of LHC IR "Y" chamber, showing that there are no trapped modes and only some small impedance spikes in the vicinity of respective cut-off frequencies of the beam pipes are present, contrary to what was originally accounted for. A new study was started, still being in progress, concerning a new secondary collimator geometry, contemplating a BPM dedicated slot. During this period, he also refined his education in Accelerator Physics, attending the Joint Universities Accelerator School for five weeks and the series of mandatory courses and seminars provided by the PhD program.

PhD thesis: Wake fields and impedance calculations of LHC collimators’ real structures

Publications