Results 11 - 20 of 10259
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[en] Nuclear track emulsion is exposed to a beam of radioactive 8He nuclei with an energy of 60 MeV and enrichment of about 80% at the ACCULINNA separator. Measurements of 278 decays of the 8He nuclei stopped in the emulsion allow the potential of the α spectrometry to be estimated and the thermal drift of 8He atoms in matter to be observed for the first time.
[en] Most existing flocking algorithms assume one single virtual leader and rely on information on both relative positions and relative velocities among neighboring agents. In this paper, the problem of controlling a flock of mobile autonomous agents to follow multiple virtual leaders is investigated by using only position information in the sense that agents with the same virtual leader asymptotically attain the same velocity and track the corresponding virtual leader based on only position measurements. A flocking algorithm is proposed under which every agent asymptotically attains its desired velocity, collision between agents can be avoided, and the final tight formation minimizes all agents' global potentials. A simulation example is presented to verify and illustrate the theoretical results. (general)
[en] The authors present the results of a year-long survey of the indoor radon concentration levels in the FYR of Macedonia. A total number of 437 dwellings in eight statistical regions were subject to radon concentration measurements by using CR-39 track detectors. The annual mean indoor radon concentration in each measuring site was estimated from the four individual measurements with 3 months duration. The measuring period was from December 2008 to December 2009. The distribution of the results was nearly log-normal. The arithmetic and geometric mean values of the annual mean value of radon concentration were estimated to be 105±84 and 84*/1.9 Bq m-3, respectively. The annual effective dose due to indoor exposure to radon in the dwellings was estimated to be 2.1*/1.9 mSv y-1. (authors)
[en] The analysis of data from CLAS is a multi-step process. After the detectors for a given running period have been calibrated, the data is processed in the so called pass-1 cooking. During the pass-1 cooking each event is reconstructed by the program a1c which finds particle tracks and computes momenta from the raw data. The results are then passed on to several data monitoring and filtering utilities. In CLAS software, a filter is a parameterless function which returns an integer indicating whether an event should be kept by that filter or not. There is a main filter program called g1-filter which controls several specific filters and outputs several files, one for each filter. These files may then be analyzed separately, allowing individuals interested in one reaction channel to work from smaller files than using the whole data set would require. There are several constraints on what the filter functions should do. Obviously, the filtered files should be as small as possible, however the filter should also not reject any events that might be used in the later analysis for which the filter was intended
[en] Possibilities of improvement of flux and dirt loading capacity of particle track membranes have been examined. Three different ways were investigated: using a divergent ion beam for the irradiation; enlarging the surface porosity through a conical pore shape; creating an asymmetrical membrane structure with two different porosities. Mathematical models and experimental results have been discussed. 9 figs, 3 tabs
[en] We present a novel vertex finding technique. The task is formulated as a discrete-continuous optimisation problem in a way similar to the deformable templates approach for the track finding. Unlike the track finding problem, ''elastic hedgehogs'' rather than elastic arms are used as deformable templates. They are initialised by a set of procedures which provide zero level approximation for vertex positions and track parameters at the vertex point. The algorithm was evaluated using the simulated events for the LHC CMS detector and demonstrated good performance. (orig.)
[en] How to monitor the beam in a particle accelerator - to measure beam position, intensity, profile, transverse and longitudinal emittance, and losses - was the topic of the first US National Workshop on Accelerator Instrumentation, at Brookhaven in October. Sponsored by the US Department of Energy, the meeting drew more than a hundred physicists and engineers from other national labs and from industry
[en] Theoretical ideas on the formation and evolution of charged particle tracks in a condensed medium are discussed. The historical development of the field is briefly reviewed. The distribution of charged particle energies over quantum states and the volume of the absorbing medium are considered, and conditions for the formation of various track structures (entities) are discussed. The structures of extended heavy-ion tracks are compared for some ion parameters and track characteristics under equal conditions. Relaxation processes in the tracks of multiply charged ions are analyzed. Track effects are considered and possible mechanisms for the formation of chemically active defects in a latent track are described. (reviews of topical problems)
[en] We investigate deviation from the tribimaximal mixing in the case of ultrahigh energy neutrino using the ICECUBE detector. We consider the ratio of the number of muon tracks to the shower generated due to eletrons and hadrons. Our analysis shows that for tribimaximal mixing the ratio comes out around 4.05. Keeping θ12 and θ23 fixed at tribimaximal value, we have varied the angle θ13=3 deg. , 6 deg. , 9 deg. and the value of the ratio gradually decreases. The variation of ratio lies within 8% to 18% from the tribimaximal mixing value and it is very difficult to detect such a small variation by the ICECUBE detector
[en] Purpose: Investigate capability and accuracy of Kinect v2 camera for tracking respiratory motion to use as a tool during 4DCT or in combination with motion management during radiotherapy treatments. Methods: Utilizing the depth sensor on the Kinect as well as code written in C#, the respiratory motion of a patient was tracked by recording the depth (distance) values obtained at several points on the patient. Respiratory traces were also obtained using Varian’s RPM system, which traces the movement of a propriety marker placed on the patient’s abdomen, as well as an Anzai belt, which utilizes a pressure sensor to track respiratory motion. With the Kinect mounted 60 cm above the patient and pointing straight down, 11 breathing cycles were recorded with each system simultaneously. Relative displacement values during this time period were saved to file. While RPM and the Kinect give displacement values in distance units, the Anzai system has arbitrary units. As such, displacement for all three are displayed relative to the maximum value for the time interval from that system. Additional analysis was performed between RPM and Kinect for absolute displacement values. Results: Analysis of the data from all three systems indicates the relative motion obtained from the Kinect is both accurate and in sync with the data from RPM and Anzai. The absolute displacement data from RPM and Kinect show similar displacement values throughout the acquisition except for the depth obtained from the Kinect during maximum exhalation (largest distance from Kinect). Conclusion: By simply utilizing the depth data of specific points on a patient obtained from the Kinect, respiratory motion can be tracked and visualized with accuracy comparable to that of the Varian RPM and Anzai belt.