We describe the most recent efforts made by various groups in implementing resistive electrodes in micropattern gaseous detectors with the aim to combine in the same design the best features of ...Resistive Plate Chambers (RPCs)—for example, their robustness and spark-protection property—with the high granularity and thus the good position resolution offered by microelectronic technology. In the stream of this activity, we have recently developed two novel detectors with resistive electrodes; one based on resistive micromeshes and the second one is a microstrip gas chamber with resistive electrodes. We have demonstrated that the resistive meshes are a convenient construction element for various designs of spark-protective detectors, for example of parallel-plate or micropattern types. These new detectors enable considerable enhancement of the RPC and micropattern detectors applications since they feature not only high position resolution but also relatively good energy resolution (25–30% full width at half maximum and at 6
keV) and, if necessary, they can operate in the cascaded mode, allowing the achievement of a high overall gas gain.
Despite an already long and fruitful history, gaseous elementary particle detectors remain an important mainstay of high-energy and nuclear physics experiments and of radiation detection in general. ...Here we briefly describe some of the gaseous detector's main technologies and applications, along with some unsolved gas-discharge physics aspects of practical relevance.
Reaction Injection Moulding, RIM, is a technology for the production reactive in situ polymerization from the mixing of two or more liquid monomers. Although RIM is a widely used process, nowadays ...there are no means to effectively control mixing. This work assesses a control new variable parameter for mixing in RIM: the differential static pressure between the liquid monomers injectors. This control variable is related to the mechanical properties of injected RIM parts. The dynamics of the control variable is also assessed. A theoretical model is introduced to relate the control variable with the mixing conditions in RIM.
•A new control technology for Reaction Injection Moulding is poven.•Polyurethane properties are related with mixing control variable values.•A model is introduced for the control variable setting.•The control variable is tested both from its average and from its dynamics.
Reaction Injection Moulding, RIM, is a technology for the production of plastic parts using reactive in situ polymerization from the mixing of two or more liquid monomers. Although RIM is a widely used process, nowadays there are no means to effectively control mixing. This work assesses a new control variable of mixing in RIM: the differential static pressure between the liquid monomers injectors. This control variable is related to the mechanical properties of injected RIM parts. The dynamics of the control variable is also assessed. A model is introduced to relate the control variable with the mixing conditions in RIM.
The results of an experimental feasibility study of a position sensitive thermal neutron detector based on a resistive plate chamber (RPC) are presented. The detector prototype features a thin-gap ...(0.35 mm) hybrid RPC with an aluminium cathode and a float glass anode. The cathode is lined with a 2 μm thick 10B4C neutron converter enriched in 10B. A detection efficiency of 6.2% is measured at the neutron beam (λ=2.5 Å) for normal incidence. A spatial resolution better than 0.5 mm FWHM is demonstrated.
We have developed a cost-effective technology for manufacturing various layouts of micropattern gaseous detectors for a wide range of applications. Such devices feature resistive electrodes ...interfaced to a network of thin readout strips/electrodes. The following three examples of such innovative designs and their applications will be presented: a prototype of a novel double-phase liquid argon detector with a CsI photocathode immersed inside the liquid argon, a CsI-RICH detector prototype for the ALICE upgrade and GEM-like sensors for environmental safety/security applications.
•Micropattern gaseous detectors.•Dual phace noble liquid TPC.•Resistive microhole-microdot detector.•CsI photocathode.•Resistive microstrip detector.•Rn detector.•Flame detector.
The complex task of describing computationally two‐phase turbulent flows in aerated stirred‐tank reactors was overcome by proposing that the gas flow rate in the hollow impeller can be estimated from ...single‐phase flow simulations of the liquid phase in the reactor: the pressure at the impeller surface obtained from liquid phase simulations can be related to the gas induction rate. A commercial lab‐scale reactor with a radial six‐bladed hollow impeller was chosen for the study. To validate the presented methodology, the induced gas flow rate was measured experimentally from the tracking of the position of bubbles in a dynamic sequence of flow images. Notwithstanding the simplifications assumed in the presented CFD methodology, good agreement has been obtained between numerical results and experiments.
Compared to other methods promoting gas dispersion, hollow self‐inducing impellers are an interesting solution when the recycling gas is costly or hazardous. A methodology for a simpler estimation of the gas flow rate from single‐phase computational fluid dynamics simulations is proposed. The suggested hypothesis is valid for lower values of induced gas flow rate by comparison with experimental results.
•Changes in the homogenisation conditions influenced the particles size of the mixes.•Particle size and fat concentration affected the viscosity of the ice cream mixes.•Mixes’ flow curves can be ...described by a modified Carreau-Yasuda model.•A model was proposed to predict the whole particle size distribution of the mixes.
The properties of ice cream are intrinsically linked to its microstructure. One of the most important characteristics of ice cream mixes is particle size distribution, which have a direct effect on stability, rheology, melting behaviour and overall quality. Homogenisation is a key process used to disrupt fat globules and achieve the desired size. Previous studies have investigated droplet breakup mechanisms in different emulsification devices and regimes, including high-pressure homogenisers. In this work, the effect of homogenisation on the fat droplet size and viscosity of aged ice cream mixes was investigated. The mode of the fat globules decreased with increasing pressure, and the viscosity increased with homogenisation pressure drop and fat content. Both were found to follow a power-law trend, where the pressure showed to be the greatest influence. A model was proposed to describe the whole particle size distribution of aged ice cream mixes, using three log-normal functions.
The TRASGO project develops high resolution tracking detectors, sensitive to single electrons and muons as well as to bundles of both kinds of particles. Two detectors are now operative and two more ...stations will start taking data for atmospheric studies soon. Thanks to the identification capability of the detectors, they are well suited to estimate the arrival rates of primary cosmic rays with different energy thresholds. This is validated after performing several simulations and opens new possibilities in the research of cosmic rays from ground-based detectors.
The capability of covering very large areas at low cost, besides showing excellent performance in many aspects, motivated the application of RPCs to Nuclear and High Energy Physics and also to Cosmic ...Ray Physics research in experiments such as COVER-PLASTEX and ARGO/YBJ. The RPCs capabilities could be used to measure new observables, or to improve resolution of actual ones, namely the sensitivity to the details of the depth development of extensive air showers from muon time distributions. Since these detectors so far have been used in indoor conditions, the main challenge is to develop detectors that can operate under harsh conditions, low energy budget, low cost per unit area, with very sparse opportunities for maintenance, and with good resilience to environmental conditions. Since the greatest challenges are the high voltage distribution/insulation and gas tightness we confine the detector in a sealed plastic box. With this approach we decouple the readout electrodes from the high voltage, allowing for different readout electrode distributions and respecting the requirements of each system with reduced effort. The detector is impervious to humidity and requires only 0.4 cm super(3)/min of gas flow rate, equivalent to 1 kg/year of R-134a.
Large area arrays composed by dispersed stations are of major importance in experiments where Extensive Air Shower (EAS) sampling is necessary. In those dispersed stations, detectors that require ...very low maintenance and show good resilience to environmental conditions are mandatory. In 2012, our group started to work in Resistive Plate Chambers that could become acceptable candidates to operate within these conditions. Since that time, more than 30 complete detectors were produced, tested and installed in different places, both indoor and outdoor. The data and analysis presented here are mainly related to the tests made in the Auger site in real conditions, where two Resistive Plate Chambers have been under test for more than two years. The results confirm the capability to operate such kind of Resistive Plate Chambers for long time periods under harsh conditions at a stable efficiency. In the last years, Laborat'{o}rio de Instrumentação e F'{i}sica Experimental de Part'{i}culas and USP—São Carlos have led a collaboration with the aim of installing an Engineering Array at BATATA (Auger) site to learn in more detail and improve the resilience and performance of the Resistive Plate Chambers in outdoor conditions. The organization of such collaboration and the work done so far will be presented.
PDF
