Results 1 - 10 of 2656
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[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] The stunning invention of the Wilson chamber in 1911 stayed almost ignored by the physicist community for more than a decade although it permitted the visualization of the track of an alpha particle as soon as 1911. The detection principle is based on the expansion of a saturated vapor that allows the visualization of a ionizing particle motion through the formation of droplets around the ions created all along the particle path. The original device was too slow (only one expansion per minute) to be used for the detection of rare events unless to operate it for months or years. A decisive step was made in the beginning of the twenties by the Japanese physicist Takeo Shimizu, working at the Cavendish Laboratory. He managed to automate the Wilson chamber and to equip it with 2 mirrors and a camera. This new generation allowed 5 expansion per second and the knowledge of the particle track orientation in space thanks to a simultaneous photography following 2 perpendicular directions. A rate of 4 shots a minute was achieved. The Wilson chamber was constantly improved during its 30 years long career and was only supplanted by the bubble chamber in the fifties. (A.C.)
[en] The particle tracking autoradiography(PTA) is a very useful method to investigate the boron distribution through the large sample area. The PTA method for boron uses the phenomenon that boron irradiated by neutron emits Li-ion and alpha particle; boron distribution can be obtained by observing the traces of the emitted particles. At HANARO in KAERI, a study for observing the boron distribution has been performed for several years. Recently, the experimental techniques were improved to provide reliable images for samples of various composition. In this report, the PTA method and experimental techniques were described in detail and the experimental results of the sample polishing, the amount of neutron irradiation and the etching time were reported. As a result, the optimum conditions for the analysis of boron distribution with respect to the amount of added boron were appeared
[en] Characterizing and localizing electronic energy degeneracies is important for describing and controlling electronic energy flow in molecules. We show, using topological phase considerations, that the Renner effect in polyatomic molecules with more than three nuclei is necessarily accompanied by 'satellite' conical intersections. In these intersections the non-adiabatic coupling term is on average half an integer. We present ab initio results on the tetra-atomic radical cation C2H+2 to demonstrate the theory. (fast track communication)
[en] Solid-state nanopores have been widely used as building blocks for nanofluidic devices and circuits from both fundamental and application aspects. In this review, we sketch the recent research progress in our group on the fabrication and application of single nanopores in PET membrane by track-etching method. The asymmetric ion transport properties in the conical nanopore are intensively studied both experimentally and theoretically. Based on the understanding of the particular ion transport behavior on nano-scale, some applications are present, including the pressure-driven streaming current and synthetic nanopore-DNA system.
[en] The performance of a particle tracking algorithm which detects particle trajectories from discretely recorded particle positions could be substantially hindered by the input noise. In this paper, a particle tracking algorithm is developed which is robust against input noise. This algorithm employs the regression method instead of the extrapolation method usually employed by existing algorithms to predict future particle positions. If a trajectory cannot be linked to a particle at a frame, the algorithm can still proceed by trying to find a candidate at the next frame. The connectivity of tracked trajectories is inspected to remove the false ones. The algorithm is validated with synthetic data. The result shows that the algorithm is superior to traditional algorithms in the aspect of tracking long trajectories
[en] A search for Q-balls has been carried out in Super-Kamiokande II with 541.7 days of live time. A neutral Q-ball passing through the detector can interact with nuclei to produce pions, generating a signal of successive contained pion events along a track. No candidate for successive contained event groups has been found in Super-Kamiokande II, so we obtain upper limits on the flux of such Q-balls
[en] The study of filtration properties of nuclear track membranes for removing the standard insoluble particles from liquid and its flux has been carried out. Furthermore, the blocking effect of micro-pore and the membrane polluted correlation factor will be presented in the paper in detail
[en] The PANDA experiment at the future FAIR facility requires yet another challenging step in detector technology. The high luminosity of the HESR ring puts strong requirements on Particle Identification for the entire detector acceptance. A proposed novel type of detector, a time-of-propagation DIRC will yield the required separation for charged tracks in the angular range between 5 and 22 degree. The anticipated high luminosity and good timing resolution required by the TOP DIRC puts constraints on the required Front End Electronics.