Multipulse operation of a high average power, good beam qualityzig-zag dye laser

A laser pumped zig-zag dye laser operating at 568 nm with a pulse length ~2 μs has been sealed to high power using a MOPA configuration. Pulse energies in excess of 7 J with beam quality <2 XDL have been achieved under repetitively pulsed, 10 Hz operation. RMS jitter was measured as 0.12 of a 1 XDL spot. The device has operated with over 70 W output for runs up to 5 s. Substantially longer run times and output powers are possible. This device represents an advance in dye laser capabilities. Improvement in pointing accuracy of better than an order of magnitude have been demonstrated. In addition, an improvement in beam quality by about an order of magnitude has been achieved compared to other dye lasers operating in this power range     

Electrical characterization of very-narrow-gap bulk HgCdTe single crystals by variable magnetic field hall measurements

Variable-magnetic-field Hall measurements (0 to 1.5 T) are performed on very-narrow-gap bulk-grown Hg_1−xCd_xTe single crystals (0.165 ≤ x ≤ 0.2) at various temperatures (10 to 300K). The electron densities and mobilities are obtained within the one-carrier (electrons) approximation of the reduced-con-ductivity-tensor scheme. The present data together with the selected data set reported by other workers exhibit a pronounced peak when the electron mobility is plotted against the alloy composition x-value which has been predicted to be due to the effective-mass minimum at the bandgap-crossing (E_g ≈ 0). The observed position (x ≈ 0.165), height (≈4 x 10² m²Vs), and width (≈0.01 in x) of the mobility-peak can be explained by a simple simulation involving only ionized-impurity scattering. A lower bound of the effective mass is introduced as a fitting parameter to be consistent with the finiteness of the observed electron mobility and is found to be of the order of 10⁻⁴ of the mass of a free electron.     

Inclusive production of neutral vector mesons in hadronic Z decays

A data sample of about 3.0 million hadronicZ decays collected by the ALEPH experiment at LEP in the years 1991 through 1994 is used to make an inclusive selection of B hadron events. In this event sample 4227±140±252B* mesons in the decayB*→Bγ and 1944±108±161B** _u,d mesons decaying into a B meson and a charged pion are reconstructed. Here and in the followingB** _u,d denotes the eightL=1(bū) and (bd) states and their charge conjugate. For the well establishedB* meson the following quantities are obtained:ΔM=M _B*−M_B=(45.30±0.35±0.87) MeV/c² andN _B*/(N _B+N _B*)=(77.1±2.6±7.0)%. The angular distribution of the photons in theB* rest frame is used to measure the relative contribution of longitudinalB* polarization states to beσ _L/(σ _L+σ _T)=(33±6±5)%.     

About non-linear realization of quantumSL q(2, R) group

Published in Teoreticheskaya i Matematicheskaya Fizika, Vol. 95, No. 2, pp. 183–186, May, 1993.     

Packed hyper-ellipsoid classifiers

Pattern classification is frequently performed using the k-nn algorithm or a neural network. The choice of parameters for the former is often difficult and the amount of data which has to be stored in the classifier can be high. Neural network classifiers can overcome some of these problems but learning is often unreliable and slow. An alternative which combines some of the best features of the k-nn and neural network classifier is described by the authors. The classifier is called a packed hyper-ellipsoid classifier     

Wideband chirp measurement technique for high bit rate sources

A Mach Zehnder (MZ) interferometer has been used as an optical discriminator to measure the time-resolved frequency chirp of an optical source     

Vibrational control of crystal growth from liquid phase

Modeling and numerical simulations of the convective flows induced by the vibration of the monocrystal during crystal growth have been performed for two configurations simulating the Cz and FZ methods. This permitted to emphasize the role of different vibrational mechanisms in the formation of the average flows. It is shown that an appropriate combination of these mechanisms can be used to counteract the usual convective flows (buoyancy- and/or thermocapillary-driven) inherent to crystal growth processes from the liquid phase. While vibrational convection is rather complex due to these identified mechanisms, the new modeling used in the present paper opens up very promising perspectives to efficiently control heat and mass transfer during real industrial applications of crystal growth from the liquid phase.