Studies on diffusion. Part I. Diffusion of radioactive matter through plates

As a part of an attempt to develop new methods of measurement of diffusion constant of metals and non-metals into minerals using radioactivity techniques, expressions are derived to relate the processes of diffusion and the emission of alpha-particles under three sets of possible experimental conditions. The first case pertaisn to a plate whose thickness is equal to the characteristic range of the alpha-rays of the radio-nuclide used. Under the second case is considered a plate thicker than the characteristic range fo the alpha-rays in the plate. The third deals with cases wherein the radioactive matter used emits alpha-rays with different ranges less than the thickness of the plate

Optimal placement of Femto base stations in enterprise femtocell networks

Femto cells a.k.a. Low Power Nodes (LPNs) are deployed to improve indoor data rates as well as reduce traffic load on macro Base Stations (BSs) in 4G/LTE cellular networks. Indoor UEs getting high SNR (Signal-to-Noise Ratio) can experience good throughput, but SNR decreases at faster rate due to obstacles, present along the communication path. Hence, efficient placement of Femtos in enterprise buildings is crucial to attain desirable SNR for indoor users. We consider obstacles and shadowing effects by walls and include them in the system model. We develop a Linear Programming Problem (LPP) model by converting convex constraints into linear ones and solve it using GAMS tool, to place Femtos optimally inside the building. Our extensive experimentation proves the optimal placement of Femtos achieves 14.41% and 35.95% increase in SNR of indoor UEs over random and center placement strategies, respectively

An indigenous cluster beam apparatus with a reflectron time-of-flight mass spectrometer

The design and fabrication of a Smalley-type cluster source in combination with a reflectron based time-of-flight (TOF) mass spectrometer are reported. The generation of clusters is based on supersonic jet expansion of the sampling plume. Sample cells for both liquid and solid targets developed for this purpose are described. Two pulsed Nd-YAG lasers are used in tandem, one (532 nm) for target vapourization and the other (355 nm) for cluster ionization. Methanol clusters of nuclearity up to 14 (mass 500 amu) were produced from liquid methanol as the test sample. The clusters were detected with a mass resolution of ~2500 in the R-TOF geometry. Carbon clusters up to a nuclearity of 28 were obtained using a polyimide target. The utility of the instrument is demonstrated by carrying out experiments to generate mixed clusters from alcohol mixtures

Centrality Dependence of Neutral Pion Production in 158 A GeV Pb + Pb Collisions

The production of neutral pions in 158AGeV Pb+Pb collisions has been studied in the WA98 experiment at the CERN SPS. Transverse momentum spectra are studied for the range 0.3 GeV/c < mT-m0 < 4.0 GeV/c. The results for central collisions are compared to various models. The centrality dependence of the neutral pion spectral shape and yield is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with greater than about 30 participating nucleons which is most naturally explained by assuming an equilibrated system.Comment: 5 pages, Latex, including 3 eps figures, submitted to Phys.Rev.Lett; updated pQCD comparison due to new input from the author, updated references, corrected plotting error in figure

Full vs Partial Market Coverage with Minimum Quality Standards

The consequences of the adoption of quality standards on the extent of market coverage is investigated by modelling a game between regulator and low-quality firm in a vertically differentiated duopoly. The game has a unique equilibrium in the most part of the parameter range. There exists a non-negligible range where the game has no equilibrium in pure strategies. This result questions the feasibility of MQS regulation when firms endogenously determine market coverage