Search for Three-Body-Force Effects in the Reaction 2H(α, αp)n at E α = 45 MeV

A kinematically complete α-induced deuteron break-up experiment has been performed at 45 MeV. An analysis based on single-level R-matrix theory and a simple formalism of the three-body interaction reveals that data around the collinearity region may indicate three-body-force effects. Received October 24, 1994; revised January 24, 1995; accepted for publication February 7, 1995     

Inexpensive automated electropneumatic syringe dispenser

An inexpensive logic-addressable, pneumatically driven syringe dispenser utilizes two three-way valves for pneumatic control and one low-volume, inert three-way valve for liquid suction and delivery. Microliter volumes of liquid can be delivered precisely at high repetition rates (720 h^?1) against significant back-pressure.     

Laser etching of Thoria pellets for microstructural investigations

Metallographic investigation of the microstructure of sintered Thoria pellets necessitates appropriate surface preparation of these pellets. Conventional etching methods involving either chemical or thermal etching techniques being unsuitable for surface etching of irradiated Thoria fuel, laser-based surface treatment was envisaged as a potential alternative technique. Thoria pellets were subjected to laser surface treatment using a pulsed Nd:YAG laser.Our preliminary studies have successfully demonstrated laser etching of sintered Thoria pellets with good reproducibility, clearly revealing grain structures and well-defined grain boundaries. Detailed parametric investigations determining optimum laser parameters for the process, are presented. Our results on ultra-short laser-based etching of sintered Thoria pellets are also discussed.     

<Emphasis Type="Italic">Z</Emphasis>-scan measurement of optical nonlinearity in solid-state dye doped media

Nonlinear refraction in various polymethyl methacrylate (PMMA) solid hosts when doped with fluorescent organic dyes, commonly used as a laser active medium, has been studied. The observed thermal lensing effect arising from optical nonlinearity, results from non-radiative energy transfer from the dye molecules to the solid matrix and is, therefore, strongly dependent on the thermal properties and material parameters of the polymeric host. The non-linear index of refraction, n₂, for each sample of dye doped polymeric host, has been measured employing the standard Z-scan technique. These measured values of n₂, have been used to determine the extent of variation in the index of refraction with varying temperature, dn/dT, for the various host materials. Estimation of dn/dT is critical in determining the extent of thermal lensing in the dye doped solid-state medium, that in turn determines the spatial quality and divergence of the generated laser beam delivered by a dye doped solid-state laser system. PACS 42.55.Mv; 42.65.Jx; 42.70.Jk     

Identifying neutrino mass hierarchy at extremely small theta13 through earth matter effects in a supernova signal

Collective neutrino flavor transformations deep inside a supernova are sensitive to the neutrino mass hierarchy even at extremely small values of theta_(13). Exploiting this effect, we show that comparison of the antineutrino signals from a galactic supernova in two megaton class water Cherenkov detectors, one of which is shadowed by Earth, will enable us to distinguish between the hierarchies if sin(2)theta_(13) < or approximately 10(-5), where long baseline neutrino experiments would be ineffectual.     

Extraction of difference of two images using periodic carrier modulation

The optical method of extraction of difference between transparencies using periodic carrier modulation was first proposed and successfully demonstrated by Pennington. His method was based on the modulation of each of the image transparencies by the same grating with the difference that one modulating carrier was shifted by half-period with respect to the other. In order to ensure extraction of difference signal from unwanted sum signal, the modulating carrier frequency must be too low. This poses a serious problem because shifting a high frequency grating exactly by a half-period is not an easy task. In order to surmount this difficulty Belvaux and Lowenthal proposed that instead of using a grating, the images transparencies can be modulated by fringes obtained in a Wollaston prism. It is well-known that these fringes can be shifted by a half-period by rotating an analyzer at the output side by 90°. The optical methods of subtraction of images suffer from the disadvantage that the photographic record has to be developed and fixed by wet processes. The processed record is then Fourier transformed and suitably filtered to extract the difference signal. In the present paper we have carried out extraction of difference of two images using the principle of periodic carrier modulation by carrying out spatial frequency filtering of the total irradiance distribution numerically. Some of the results of subtraction are presented.     

Nickel(0)-catalyzed cyclization of N-benzoylaminals for isoindolinone synthesis

A nickel(0) catalyst effectively mediates the cyclization of N-benzoyl aminals in the presence of a stoichiometric Lewis acid. This method enables preparation of a variety of isoindolinones with substitution on the benzoyl fragment and C-3 carbon. This reaction likely proceeds via an α-amidoalkylnickel(II) intermediate, which then may cyclize via either an electrophilic aromatic substitution or an insertion pathway.