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Background: Nuclear waste management is considered amongst the major challenges in the field of nuclear energy. A possible means of addressing this issue is waste transmutation in advanced nuclear systems, whose operation requires a fast neutron spectrum. In this regard, the accurate knowledge of neutron-induced reaction cross sections of several (minor) actinide isotopes is essential for design optimization and improvement of safety margins of such systems. One such case is 240 Pu , due to its accumulation in spent nuclear fuel of thermal reactors and its usage in fast reactor fuel. The measurement of the 240 Pu ( n , f ) cross section was previously attempted at the CERN n_TOF facility EAR1 measuring station using the time-of-flight technique. Due to the low amount of available material and the given flux at EAR1, the measurement had to last several months to achieve a sufficient statistical accuracy. This long duration led to detector deterioration due to the prolonged exposure to the high a activity of the fission foils, therefore the measurement could not be successfully completed. Purpose: It is aimed to determine whether it is feasible to study neutron-induced fission at n_TOF/EAR2 and provide data on the 240 Pu ( n , f ) reaction in energy regions requested for applications. Methods: The study of the 240 Pu ( n , f ) reaction was made at a new experimental area (EAR2) with a shorter flight path which delivered on average 30 times higher flux at fast neutron energies. This enabled the measurement to be performed much faster, thus limiting the exposure of the detectors to the intrinsic activity of the fission foils. The experimental setup was based on microbulk Micromegas detectors and the time-of-flight data were analyzed with an optimized pulse-shape analysis algorithm. Special attention was dedicated to the estimation of the non-negligible counting loss corrections with the development of a new methodology, and other corrections were estimated via Monte Carlo simulations of the experimental setup. Results: This new measurement of the 240 Pu ( n , f ) cross section yielded data from 9 meV up to 6 MeV incident neutron energy and fission resonance kernels were extracted up to 10 keV . Conclusions: Neutron-induced fission of high activity samples can be successfully studied at the n_TOF/EAR2 facility at CERN covering a wide range of neutron energies, from thermal to a few MeV.

In particle physics research centers like CERN, it is critical to monitor the movements of devices inside the particle accelerator. When a technical issue in the tunnel occurs, the particle beams with high kinetic energy are sent, via two detours in the main ring, to two mainly metal absorber blocks, the so-called beam dumps, in order to stop them. The massive kinetic energy deposited on these dumps can cause them to move. Accelerometers are one measurement device that can be used to monitor the acceleration and, indirectly, the position of the dumps. In this thesis, the mechanical structure of an interferometer-based inertial accelerometer with a flexible membrane has been designed. In order to reduce the accelerator beam kinetic energy, a helical movement occurs in the particle beams, it was therefore necessary to measure the acceleration in the three spatial axes so a three-axis accelerometer is considered. As part of the theoretical approach, it was needed to focus on the requirements provided and to analyze the deformation, stress, and vibration of the structure. To ensure its reliability and precision, FEM analysis using ANSYS 19.1 was used and crosschecked by hand. After the theoretical approach, those characteristics were ensured with different types of experimental tests, such as an impact or vibration test. As a conclusion, theoretical requisites of the accelerometer have been met, except the complete linearity of the frequency response. The non-accomplishment of this requirement may lead to some error on the higher frequency acceleration measurements

High statistics samples of reconstructed charmed particles have been obtained by the NA14' experiment. Signals are presented in a variety of decay channels, and are used for the measurement of lifetimes and the study of production mechanisms.