Specification and Verification of Synchronous Hardware using LOTOS

This paper investigates specification and verification of synchronous circuits using DILL (Digital Logic in LOTOS). After an overview of the DILL approach, the paper focuses on the characteristics of synchronous circuits. A more constrained model is presented for specifying digital components and verifying them. Two standard benchmark circuits are specified using this new model, and analysed by the CADP toolset (Cæsar/Aldébaran Development Package)

Nuclear decay scheme studies using radiative capture of thermal neutrons

Ph.D.D. A. McClur

Cosmic Ray and Neutrino Astrophysics with the ANITA III Telescope.

Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017

Development of carbon dioxide laser doppler instrumentation detection of clear air turbulence

The analytical, experimental, and developmental aspects of an airborne, pulsed, carbon dioxide laser-optical radar system are described. The laser detects clear air turbulence and performs Doppler measurements of this air-motion phenomenon. Conclusions and recommendations arising from the development of the laser system are presented

NUMERICAL AND LABORATORY STUDY OF SEISMIC WAVES PROPAGATION, TEMPERATURE EFFECTS AND FLUID FLOWS IN MULTILAYERED MEDIA

Steel production by continuous casting is nowadays the most efficient method and the one that yields the best quality semi-finished products. The types of steel that can be produced varies greatly depending on the composition of the mixtures, the casting powders used to prevent oxidation and reduce heat loss, the cooling rate, and many other factors. During continuous casting, heat from the molten steel must be removed in large quantities and quickly to allow the first layer of solid skin to be created, so the continuous casting moulds, i.e. large hollow tubes generally made of copper alloys, are immersed in a conveyor with a closed water circuit where water circulates at high speed and pressure. In addition to water, there are also other parameters that can be monitored to increase production quality, such as powder deposition on the casting bath and steel level control. It would be useful to have automatic systems capable of replacing manual human control, to avoid the hazardous situations obviously present in steel mills, but also to increase knowledge of the production process through the acquisition of reliable data. This research aims to experimentally explore the possibility of measuring the level of molten steel in the mould by making time-of-flight measurements in the wall of the ingot using ultrasonic transducers similar the ones used for non-destructive testing of materials. These time-of-flight measurements are then converted to temperature and determine a thermal profile along the mould wall, from which the steel level is derived using an ad-hoc constructed algorithm. The research activity was divided into the realization of a real-time hardware and software system that was eventually adopted in real production systems as well. To understand how to design an initial prototype and how to choose the key parameters of the measurement system, a numerical model was implemented to simulate Gaussian beams, which are used to approximate the propagation of ultrasonic beams in even heterogeneous media, as in this case. The results obtained, both from numerical simulations and laboratory tests, made it possible to implement a first measurement tool that adopted a technique already known in the literature but innovative in the sense of application to an industrial context such as continuous castingSteel production by continuous casting is nowadays the most efficient method and the one that yields the best quality semi-finished products. The types of steel that can be produced varies greatly depending on the composition of the mixtures, the casting powders used to prevent oxidation and reduce heat loss, the cooling rate, and many other factors. During continuous casting, heat from the molten steel must be removed in large quantities and quickly to allow the first layer of solid skin to be created, so the continuous casting moulds, i.e. large hollow tubes generally made of copper alloys, are immersed in a conveyor with a closed water circuit where water circulates at high speed and pressure. In addition to water, there are also other parameters that can be monitored to increase production quality, such as powder deposition on the casting bath and steel level control. It would be useful to have automatic systems capable of replacing manual human control, to avoid the hazardous situations obviously present in steel mills, but also to increase knowledge of the production process through the acquisition of reliable data. This research aims to experimentally explore the possibility of measuring the level of molten steel in the mould by making time-of-flight measurements in the wall of the ingot using ultrasonic transducers similar the ones used for non-destructive testing of materials. These time-of-flight measurements are then converted to temperature and determine a thermal profile along the mould wall, from which the steel level is derived using an ad-hoc constructed algorithm. The research activity was divided into the realization of a real-time hardware and software system that was eventually adopted in real production systems as well. To understand how to design an initial prototype and how to choose the key parameters of the measurement system, a numerical model was implemented to simulate Gaussian beams, which are used to approximate the propagation of ultrasonic beams in even heterogeneous media, as in this case. The results obtained, both from numerical simulations and laboratory tests, made it possible to implement a first measurement tool that adopted a technique already known in the literature but innovative in the sense of application to an industrial context such as continuous castin

Remodelling a multi-anode ionisation chamber detector for accelerator mass spectrometry of 53Mn

Accelerator Mass Spectrometry (AMS) is a single-atom counting technique that measures the abundance of rare, long-lived radioisotopes using only milligrams of sample. The astrophysical radioisotopes 53Mn and 60Fe have been utilised for many applications including meteoritics, exposure dating, and the search for near-Earth supernovae. 53Mn measurements at the ANU have been limited to sensitivities above 10^-13 by insufficient suppression of the stable isobar, 53Cr. To expand the applications accessible to 53Mn analysis, a new detector was commissioned that will improve the available sensitivity. This thesis covers the implementation of the new Flexible Anti-Scatter Multi-Anode (FASMA) detector. Simulations were conducted to determine the optimal placement of the detector inside the gas-filled magnet, and to assist with the design of a new multi-anode configuration. The FASMA detector was successfully tested and full spectra were recorded. These preliminary results indicate an improvement in the achievable sensitivity, even without the suppression of scattered particles. With further work, the FASMA detector should reach a sensitivity at or below 10^-14, which is competitive with the best reported level in the field. Long-lived radionuclides, such as 53Mn and 60Fe, are important for extracting the exposure history of meteorites, both in space and on Earth, as well helping to identify their origin. In light of this, cosmogenic 53Mn and 60Fe ratios were measured in ten meteorite samples. Since the available data on live 53Mn and 60Fe is scarce, these measurements will improve the constraints on current production rate models for meteorites

Charged hadron production in elementary and nuclear collisions at 158 GeV/c

A comparative study of p+p, p+Pb and Pb+Pb reactions is presented. For the first time, the same experimental apparatus is used for investigating the three reaction types. Data on identified baryons in the projectile hemisphere of p+p and centrality-selected p+Pb and Pb+Pb collisions are shown. Information from pion-induced interactions is used to isolate the projectile role in the observed phenomena. A common picture emerges for p+p, p+Pb and Pb+Pb reactions: with increasing centrality, the projectile baryon number is strongly "pushed" towards the backward hemisphere of the collision. Semi-inclusive data on identified pions in the forward hemisphere of p+p interactions are presented. The observed trends are compared to results on pion production in centrality-selected p+Pb and Pb+Pb reactions. It is argued that at least a part of effects observed in nuclear collisions can be explained by correlations present in p+p events. Conclusions about similarities and differences between elementary and nuclear reactions are drawn. The obtained results are followed by an inspection of the role played by resonance production in inelastic hadronic collisions. This role appears significant in many of the observed phenomena. Resonance decays influence both pion and proton production in a wide region of available phase-space. The contribution made to particle identification performance of the detector is described. It consists in a high precision calibration procedure, using radioactive 83Kr gas. This method is also applied for studying various detector effects

Signal coupling and signal integrity in multi-strip Resistive Plate Chambers used for timing applications

We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range $f=0.1-3.5$GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-times of signals originated in RPCs used for sub-100ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1 meter scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to the intrinsic unbalance between the capacitive and the inductive coupling $C_m/C_o \neq L_m/L_o$. A practical way to restore this symmetry has been introduced (hereafter `electrostatic compensation'), allowing for a cross-talk suppression factor of around $\times 12$ and a rise-time reduction by 200ps. Under conditions of compensation the signal transmission is only limited by dielectric losses, yielding a length-dependent cutoff frequency of around 1GHz per 2 meter for typical float glass -based RPCs ($\tan \delta|_{glass} = 0.025\pm0.005$). It is further shown that `electrostatic compensation' can be achieved for an arbitrary number of strips as long as the nature of the coupling is `short-range', that is an almost exact assumption for typical strip-line RPCs. Evidence for deviations from the dominant TEM propagation mode has been observed, although they seem to have negligible influence in practical signal observables. This work extends the bandwidth of previous studies by a factor of almost $\times 20$.Comment: submitted to NI