We have measured antiproton production cross sections as functions of centrality in collisions of 14.6 GeV/ital c per nucleon sup 28Si ions with targets of Al, Cu, and Pb. For all targets, the ...antiproton yields increase linearly with the number of projectile nucleons that have interacted, and show little target dependence. We discuss the implications of this result on the production and absorption of antiprotons within the nuclear medium.
To monitor the acidity of rain water in real time, a rain water sampling system was developed. The rain sampler detects the initial rain after a dry spell and collects a water sample. Before ...performing the measurements, the pH probe is calibrated using a standard buffer solution whereas the conductivity probe is calibrated using deionized water. After calibrating the probes the pH and the conductivity of the collected rain water sample are measured using the pH and the conductivity probe. Weather parameters such as air temperature, humidity and pressure are also recorded simultaneously. The pH and conductivity measurement data including weather parameters are transmitted to central station using a GSM modem for further analysis. The collected rain water sample is preserved at the remote monitoring station for post chemical analysis. A programmable logic controller controls the entire process.
Daily rainfall data recorded at 13 stations were analyzed to study the spatial patterns of rainfall in the dry zone of Sri Lanka. Principal component analysis was utilized to classify the dominant ...spatial regions. The first 2 eigenvectors accounted for 70.2% (the first eigenvector 54.8% and the second 15.4%) of the total variation, which clearly supports the commonly used major climatic division of Sri Lanka into wet and dry zones. Both the inverse distance weighting method and kriging successfully estimated weekly average rainfall in the North Central dry zone of Sri Lanka. For both methods, high correlation coefficients of 0.88 and 0.91 were observed for the southwest and northeast monsoon periods, respectively, with slightly lower values for intermonsoon periods. For inter-monsoon periods, the inverse distance weighting method produced better results than kriging. This work shows that the strength of the predictions depends on the rainfall seasons as well as the geometrical placement of the stations in the dry zone.
We have measured cross sections for the synthesis of nuclei of mass ital Ale4 in collisions of 14.6ital A GeV/ital c sup 28Si nuclei with targets of Pb, Cu, and Al. The data are measured at close to ...center-of-mass rapidities, and are unique in their exploration of the centrality dependence of nucleosynthesis. Simple coalescence models that were used to study nucleosynthesis at lower energies are inadequate for the description of our measurements. Our data and improved models are used to extract parameters related to the size of the interaction volume at freeze-out.
Experiments play a vital role in science education. In high school physics, especially in mechanics, many experiments are conducted where tracking a single or multiple objects are required. In most ...situations students visually observe the motion of objects and take the measurements. This manual method is time consuming, generates higher error and incapable of producing multiple readings rapidly. The research described in this work introduces a simple mechanism to integrate computer vision based tracking to enhance the quality of measurements and to new ways of looking at experiments. The case study consists of three standard experiments. In the first experiment a motion of the simple pendulum was tracked. Using computer vision students were able to obtain a correlation of 0.99 between the calculated period and the theoretical period. In addition, it was possible to calculate the position and the velocity of the bob more than 30 times during a single oscillation. Students were able to plot the extra data points for a better understanding of the simple harmonic motion, which was not possible in the manual method. Second experiment was focused on measuring the terminal velocity of a ball moving through a viscous medium. Final case study was on tracking multiple particles in a moving fluid. In all three experiments computer vision based system provided more accurate and higher number of data points than the manual method. This helps students to understanding the underline theory better. The tracking system was consisted of a digital camera, image preprocessing sub system, feature extraction subsystem, object identification subsystem and data export subsystem. The system was successfully tested on a normal PC which is cost effective to be used in high schools. Based on the case studies it was concluded that such systems can be used in high schools to improve the quality of experiments conducted.
The series of upgrades to the Large Hadron Collider, culminating in the High Luminosity Large Hadron Collider, will enable a significant expansion of the physics program of the CMS experiment. ...However, the accelerator upgrades will also make the experimental conditions more challenging, with implications for detector operations, triggering, and data analysis. The luminosity of the proton-proton collisions is expected to exceed \(2-3\times10^{34}\)~cm\(^{-2}\)s\(^{-1}\) for Run 3 (starting in 2022), and it will be at least \(5\times10^{34}\)~cm\(^{-2}\)s\(^{-1}\) when the High Luminosity Large Hadron Collider is completed for Run 4. These conditions will affect muon triggering, identification, and measurement, which are critical capabilities of the experiment. To address these challenges, additional muon detectors are being installed in the CMS endcaps, based on Gas Electron Multiplier technology. For this purpose, 161 large triple-Gas Electron Multiplier detectors have been constructed and tested. Installation of these devices began in 2019 with the GE1/1 station and will be followed by two additional stations, GE2/1 and ME0, to be installed in 2023 and 2026, respectively. The assembly and quality control of the GE1/1 detectors were distributed across several production sites around the world. We motivate and discuss the quality control procedures that were developed to standardize the performance of the detectors, and we present the final results of the production. Out of 161 detectors produced, 156 detectors passed all tests, and 144 detectors are now installed in the CMS experiment. The various visual inspections, gas tightness tests, intrinsic noise rate characterizations, and effective gas gain and response uniformity tests allowed the project to achieve this high success rate.
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