Construction and detectors’ characterization of a new detection system for FAMU Experiment

From 2010, the Proton Radius has become one of the most interest value to determine. The first proof of not complete understanding of its internal structure was the measurement of the Lamb Shift using the muonic hydrogen, leading to a value 7σ lower. A new road so was open and the Proton Radius Puzzle epoch begun. FAMU Experiment is a project that tries to give an answer to this Puzzle implementing high precision experimental apparatus. The work of this thesis is based on the study, construction and first characterization of a new detection system. Thanks to the previous experiments and simulations, this apparatus is composed by 17 detectors positioned on a semicircular crown with the related electronic circuit. The detectors' characterization is based on the use of a LabView program controlling a digital potentiometer and on other two analog potentiometers, all three used to set the amplitude of each detector to a predefined value, around 1.2 V, set on the oscilloscope by which is possible to observe the signal. This is the requirement in order to have, in the final measurement, a single high peak given by the sum of all the signals coming from the detectors. Each signal has been acquired for almost half of an hour, but the entire circuit has been maintained active for more time to observe its capacity to work for longer periods. The principal results of this thesis are given by the spectra of 12 detectors and the corresponding values of Voltages, FWHM and Resolution. The outcomes of the acquisitions show also another expected behavior: the strong dependence of the detectors from the temperature, demonstrating that an its change causes fluctuations in the signal. In turn, these fluctuations will affect the spectrum, resulting in a shifting of the curve and a lower Resolution. On the other hand, a measurement performed in stable conditions will lead to accordance between the nominal and experimental measurements, as for the detectors 10, 11 and 12 of our system.

Numerical prediction of the lateral displacement capacity of flexural reinforced concrete shear walls

Previous earthquakes showed that shear wall damage could lead to catastrophic failures of the reinforced concrete building. The lateral load capacity of shear walls needs to be estimated to minimize associated losses during catastrophic events; hence it is necessary to develop and validate reliable and stable numerical methods able to converge to reasonable estimations with minimum computational effort. The beam-column 1-D line element with fiber-type cross-section model is a practical option that yields results in agreement with experimental data. However, shortcomings of using this model to predict the local damage response may come from the fact that the model requires fine calibration of material properties to overcome regularization and size effects. To reduce the mesh-dependency of the numerical model, a regularization method based on the concept of post-yield energy is applied in this work to both the concrete and the steel material constitutive laws to predict the nonlinear cyclic response and failure mechanism of concrete shear walls. Different categories of wall specimens known to produce a different response under in plane cyclic loading for their varied geometric and detailing characteristics are considered in this study, namely: 1) scaled wall specimens designed according to the European seismic design code and 2) unique full-scale wall specimens detailed according to the U.S. design code to develop a ductile behavior under cyclic loading. To test the boundaries of application of the proposed method, two full-scale walls with a mixed shear-flexure response and different values of applied axial load are also considered. The results of this study show that the use of regularized constitutive models considerably enhances the response predictions capabilities of the model with regards to global force-drift response and failure mode. The simulations presented in this thesis demonstrate the proposed model to be a valuable tool for researchers and engineers.