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High-order harmonic generation at 4MHz as a light source for time-of-flight photoemission spectroscopy

Very intense green and red emission was observed at room temperature from the (4)S(3/2) and (4)F(9/2) levels of Er(3+):Y(2)O(3). A cw diode laser at 975 nm was used as a pump for resonant sequential excitation of the (4)I(11/2) and (4)F(7/2) levels. The fluorescence was easily visible to the naked eye, even with 27 mW of excitation power. It was found that at 850 mW of cw excitation power the total luminance was 39,000 cd/m(2). This corresponds to ~100 muW of green emission and 270 muW of red emission.

a b s t r a c tA very fast simulated annealing (VFSA) global optimization is used to interpret residual gravity anomaly. Since, VFSA optimization yields a large number of best-fitted models in a vast model space; the nature of uncertainty in the interpretation is also examined simultaneously in the present study. The results of VFSA optimization reveal that various parameters show a number of equivalent solutions when shape of the target body is not known and shape factor 'q' is also optimized together with other model parameters. The study reveals that amplitude coefficient k is strongly dependent on shape factor. This shows that there is a multi-model type uncertainty between these two model parameters derived from the analysis of cross-plots. However, the appraised values of shape factor from various VFSA runs clearly indicate whether the subsurface structure is sphere, horizontal or vertical cylinder type structure. Accordingly, the exact shape factor (1.5 for sphere, 1.0 for horizontal cylinder and 0.5 for vertical cylinder) is fixed and optimization process is repeated. After fixing the shape factor, analysis of uncertainty and cross-plots shows a well-defined uni-model characteristic. The mean model computed after fixing the shape factor gives the utmost consistent results.

A Very Fast Simulated Annealing (VFSA) global optimization algorithm is developed for interpretation of gravity and magnetic anomaly over thin sheet type structure for ore exploration. The results of VFSA optimization show that it can uniquely determine all the model parameters without any uncertainty. Inversion of noise-free and noisy synthetic data for single structures as well as field data demonstrates the efficacy of the approach. The technique has been vigilantly and efficaciously applied to two real data examples from Canada with the presence of ore bodies. In both Model examples, the model parameters acquired by the present method, mostly the shape and depth of the buried structures were found to be in respectable agreement with the actual parameters. The present method has the proficiency of evading highly noisy data points and enhances the interpretation results. The technique can be extremely appropriate for mineral exploration, where the gravity and magnetic data is observed due to ore body of sheet like structure embedded in the shallow and deeper subsurface. The computation time for the whole process is very short.