Resistive plate chambers are rugged and affordable gas detectors that have found extensive use in high-energy physics (HEP) and astroparticle experiments. The main features of these counters are the ...very large pulse height, reduced cost per unit area, and good (about 1 ns) time resolution. The field has enjoyed very lively progress in recent years, including the introduction of a new (avalanche) mode of operation, extension of the counting-rate capabilities to levels around 10 MHz/cm/sup 2/, improvement of the time resolution for minimum ionizing particles to 50 ps /spl sigma/, and the achievement of position resolutions of a few tens of micrometers. These new developments have extended the range of REP applications and promise new applications in medical imaging.
Abstract Recently we have proposed a new concept of a thermal neutron detector based on resistive plate chambers and 10 B 4 C solid neutron converters, enabling to readout with high resolution in ...both the 3D position of neutron capture and the neutron time of flight (ToF). In this paper, we report the results of the first beam tests conducted with a new neutron RPC detection module, coupled to the position readout units of a new design. The main focus is on the measurements of the neutron ToF and identification of the converter layer where the neutron is captured, giving the position along the beam direction.
Characterization of mixing in T-jets mixers Krupa, Kateryna; Sultan, M.Ashar; Fonte, Cláudio P ...
Chemical engineering journal (1996),
10/2012, Letnik:
207
Journal Article, Conference Proceeding
Recenzirano
The product distribution of a fast chemical reaction system was used for the characterization of micromixing in T-jets mixers; several geometries were assessed under different operational conditions ...(Reynolds number and jets flow rate ratio). The micromixing test system was the reaction between 1-naphthol and diazotized sulfanilic acid in an aqueous medium. The results obtained show that for all geometries mixing is enhanced with Reynolds number and with the operation at flow rate ratios close to unity. The geometrical parameters of T-jets mixers have a critical influence on the product distribution of the test reaction; particularly the ratio between the mixing chamber width and the inlet jet width, and also the mixing chamber depth. Micromixing is shown to be mainly related to the flow field regime observed at each geometry and operational conditions, which were previously set using Planar Laser Induced Fluorescence.
A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time ...resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The SHiP timing detector based on MRPC Blanco, A.; Clemencio, F.; Fonte, P. ...
Journal of instrumentation,
10/2020, Letnik:
15, Številka:
10
Journal Article
Recenzirano
Odprti dostop
SHiP (Search for Hidden Particles) is a general-purpose experiment to be installed in a new beam-dump facility at the SPS at CERN to search for hidden particles as predicted by a very large number of ...recently elaborated models. The proposed experimental apparatus contains, among others, a 50 m2 Timing Detector, crucial to reject the combinatorial background, with a requirement of a timing precision better than 100 ps together with the highest possible detection efficiency. One possibility for the construction of the Timing Detector is the Multigap Resistive Plate Chamber (MRPC) technology. In this paper, we report the design and test beam results of the first full-scale module, based on a novel concept on the construction of MRPCs, where the glass stack and high-voltage electrodes are confined within a permanently sealed plastic box, exhibiting a time precision of 54 ps together with a detection efficiency of 98% over almost 2 m2 of active area.
Stirred vessels are used to facilitate mixing processes across a wide range of industries. Their performance can often be predicted with certain characteristics of the agitator, like the ...dimensionless power and flow numbers. Since there exists a large number of agitator designs and geometries, it is desirable to be able to predict these characteristics using models rather than rely on previous experimental data. In this study, we use an angular momentum balance combined with computational fluid dynamics to correlate the power, flow, and mixer geometry across a wide range of down‐pumping pitched blade turbine geometries. The models developed from the results allow us to predict the power from the flow (or vice versa) for the geometries investigated. We tested two methods for the measurement of the flow rate and found that the choice of measurement method can affect the relationship between the power, flow, and impeller geometry.
Three analytical tools (conductivity, torque measurements and near-infrared spectroscopy (NIR)) were investigated for characterization of ice fraction (ϕice) and viscosity (μ) of water ices. Sucrose ...water ices with varying sugar content (Csuc, 5–55 wt.%) were used as model water ices. A predictive model for ice fraction analysis using conductivity measurements was developed for Csuc≥25wt.%. Due to instrument limitation, the model only provided a rough estimation of the amount of ice formed, however the results show the potential of the technique and further studies are required. The increasing ϕice can be related to the increasing μ, obtained using torque measurements. An empirical model was proposed to describe the evolution of the water ices viscosity with ice fraction, and a good correlation was found (R2=0.986). Although NIR spectroscopy proved not adequate for ice fraction analysis, the method has been applied by other authors for characterization of ice cream mixes, including rheological properties.
•The ice content depends on the sugar concentration and temperature.•Conductivity and NIR spectra can measure the concentration of the unfrozen bulk.•Viscosity of water ices is affected by the ice content.•Viscosity can be determined by the power consumption.
We present experimental results on the counting rate measurements for several single-gap 10B lined resistive plate chambers (10B-RPCs) with anodes made from standard float glass, low-resistivity ...glass and ceramic. The measurements were performed at the V17 monochromatic neutron beamline (3.35 Å) at the Helmholtz-Zentrum Berlin. For the 10B-RPCs with 0.28mm thick float glass a maximum counting rate density of about 8 × 103 Hz/cm2 was obtained. In the case of low resistivity glass and ceramic, the counting rate density did not deviate from linear dependence on the neutron flux up to the maximum flux available at this beamline and exceeded a value of 3 × 104 Hz/cm2.
The finitely extensible nonlinear elastic with Peterlin closure (FENE-P) and simplified Phan-Thien–Tanner (sPTT) viscoelastic models are used widely for modelling of complex fluids. Although they are ...derived from distinct micro-structural theories, these models can become mathematically identical in steady and homogeneous flows with a particular choice of the values of the model parameters. However, even with this choice of parameter values, the model responses are known to differ from each other in transient flows. In this work, we investigate the responses of the FENE-P and sPTT constitutive models in large-amplitude oscillatory shear (LAOS). In steady shear, the shear stress scales with the non-dimensional group $Wi/(aL)$ ($Wi\,\sqrt {\epsilon }$) for the FENE-P (sPTT) model, where $Wi$ is the Weissenberg number, $L^2$ is the limit of extensibility in the FENE-P model ($a$ being $L^2/(L^2-3)$), and $\epsilon$ is the extensibility parameter in the sPTT model. Our numerical and analytical results show that in LAOS, the FENE-P model shows this universality only for large values of $L^2$, whereas the sPTT model shows it for all values of $\epsilon$. In the strongly nonlinear region, there is a drastic difference between the responses of the two models, with the FENE-P model exhibiting strong shear stress overshoots that manifest as self-intersecting secondary loops in the viscous Lissajous curves. We quantify the nonlinearity exhibited by each constitutive model using the sequence of physical processes framework. Despite the high degree of nonlinearity exhibited by the FENE-P model, we also show using fully nonlinear one-dimensional simulations that it does not shear band in LAOS within the range of conditions studied.
Impellers in stirred vessels are often characterized by dimensionless numbers such as the power and flow numbers. These are often crucial in determining mixing performance. Previous studies for ...high‐shear mixers have yielded correlations between the power, flow, and mixer geometries, since in these mixers the flow can be independently varied. For stirred vessels, dimensional analysis is typically used to develop such correlations, leading to less accurate predictive models. Here, we combine an analysis based on a balance of angular momentum balance with computational fluid dynamics simulations to comprehensively study the effect of impeller geometry on the relationship between power and flow. The results allow for the prediction of the flow generated by the impeller based on the easily measurable impeller power consumption and the geometrical dimensions of the impeller. The models are accurate over a wide range of geometries. Furthermore, we are able to predict both the primary and total flows.
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