Development, mechanical characterization and qualification in liquid lead of stainless steels for structural applications in the future fission and fusion nuclear reactors

The research activity carried out in the Brasimone Research Center of ENEA concerns the development and mechanical characterization of steels conceived as structural materials for future fission reactors (Heavy Liquid Metal IV Generation reactors: MYRRHA and ALFRED) and for the future fusion reactor DEMO. Within this framework, two parallel lines of research have been carried out: (i) characterization in liquid lead of steels and weldings for the components of the IV Generation fission reactors (GIV) by means of creep and SSRT (Slow Strain Rate Tensile) tests; (ii) development and screening on mechanical properties of RAFM (Reduced Activation Ferritic Martensitic) steels to be employed as structural materials of the future DEMO fusion reactor. The doctoral work represents therefore a comprehensive report of the research carried out on nuclear materials both from the point of view of the qualification of existing (commercial) materials for their application in the typical environmental conditions of 4th generation fission reactors operating with lead as coolant, and from the point of view of the metallurgical study (with annexed microstructural and mechanical characterization of the selected compositions / Thermo Mechanical Treatment (TMT) options) of new compositional variants to be proposed for the “Breeding Blanket” of the future DEMO Fusion Reactor.

Measurement of CP violation with $B^0_{(s)} \to h^+ h^{\prime-}$ decays, $|V_{cb}|$ with $B^0_{s}\to D^{(*)-}_s \mu^+ \nu_\mu$ decays, and simulation and characterisation of the LHCb Upgrade II ECAL

The time-dependent CP asymmetries of the $B^0\to\pi^+\pi^-$ and $B^0_s\toK^+K^-$ decays and the time-integrated CP asymmetries of the $B^0\toK^+\pi^-$ and $B^0_s\to\pi^+K^-$ decays are measured, using the $p-p$ collision data collected with the LHCb detector and corresponding to the full Run2. The results are compatible with previous determinations of these quantities from LHCb, except for the CP-violation parameters of the $B^0_s\to K^+K^-$ decays, that show a discrepancy exceeding 3 standard deviations between different data-taking periods. The investigations being conducted to understand the discrepancy are documented. The measurement of the CKM matrix element $|V_{cb}|$ using $B^0_{s}\to D^{(*)-}_s\mu^+ \nu_\mu$ is also reported, using the $p-p$ collision data collected with the LHCb detector and corresponding to the full Run1. The measurement leads to $|V_{cb}| = (41.4\pm0.6\pm0.9\pm1.2)\times 10^{-3}$, where the first uncertainty is statistical, the second is systematic, and the third is due to external inputs. This measurement is compatible with the world averages and constitutes the first measurement of $|V_{cb}|$ at a hadron collider and the absolute first one with decays of the $B^0_s$ meson. The analysis also provides the very first measurements of the branching ratio and form factors parameters of the signal decay modes. The study of the characteristics ruling the response of an electromagnetic calorimeter (ECAL) to profitably operate in the high luminosity regime foreseen for the Upgrade2 of LHCb is reported in the final part of this Thesis. A fast and flexible simulation framework is developed to this purpose. Physics performance of different configurations of the ECAL are evaluated using samples of fully simulated $B^0\to \pi^+\pi^-\pi^0$ and $B^0\to K^{*0}e^+e^-$ decays. The results are used to guide the development of the future ECAL and are reported in the Framework Technical Design Report of the LHCb Upgrade2 detector.

The future in action: neurophysiological and behavioral evidence of anticipatory motor simulation.

The motor system can no longer be considered as a mere passive executive system of motor commands generated elsewhere in the brain. On the contrary, it is deeply involved in perceptual and cognitive functions and acts as an “anticipation device”. The present thesis investigates the anticipatory motor mechanisms occurring in two particular instances: i) when processing sensory events occurring within the peripersonal space (PPS); and ii) when perceiving and predicting others’actions. The first study provides evidence that PPS representation in humans modulates neural activity within the motor system, while the second demonstrates that the motor mapping of sensory events occurring within the PPS critically relies on the activity of the premotor cortex. The third study provides direct evidence that the anticipatory motor simulation of others’ actions critically relies on the activity of the anterior node of the action observation network (AON), namely the inferior frontal cortex (IFC). The fourth study, sheds light on the pivotal role of the left IFC in predicting the future end state of observed right-hand actions. Finally, the fifth study examines how the ability to predict others’ actions could be influenced by a reduction of sensorimotor experience due to the traumatic or congenital loss of a limb. Overall, the present work provides new insights on: i) the anticipatory mechanisms of the basic reactivity of the motor system when processing sensory events occurring within the PPS, and the same anticipatory motor mechanisms when perceiving others’ implied actions; ii) the functional connectivity and plasticity of premotor-motor circuits both during the motor mapping of sensory events occurring within the PPS and when perceiving others’ actions; and iii) the anticipatory mechanisms related to others’ actions prediction.