Measurement of E2 Transitions in the Coulomb Dissociation of 8B

In an effort to understand the implications of Coulomb dissociation experiments for the determination of the 7Be(p,gamma)8B reaction rate, longitudinal momentum distributions of 7Be fragments produced in the Coulomb dissociation of 44 and 81 MeV/nucleon 8B beams on a Pb target were measured. These distributions are characterized by asymmetries interpreted as the result of interference between E1 and E2 transition amplitudes in the Coulomb breakup. At the lower beam energy, both the asymmetries and the measured cross sections are well reproduced by perturbation theory calculations, allowing a determination of the E2 strength.Comment: 8 pages, 3 figure

On the interaction of mesoscopic quantum systems with gravity

We review the different aspects of the interaction of mesoscopic quantum systems with gravitational fields. We first discuss briefly the foundations of general relativity and quantum mechanics. Then, we consider the non-relativistic expansions of the Klein-Gordon and Dirac equations in the post-Newtonian approximation. After a short overview of classical gravitational waves, we discuss two proposed interaction mechanisms: (i) the use of quantum fluids as generator and/or detector of gravitational waves in the laboratory, and (ii) the inclusion of gravitomagnetic fields in the study of the properties of rotating superconductors. The foundations of the proposed experiments are explained and evaluated.Comment: 27 pages, study for ESA: typos corrected, references and clarifications added. To appear in Annalen der Physi

An evaluation of absorption spectroscopy to monitor YBa₂Cu₃O₇₋[x] precursors for metal organics chemical vapor deposition processing

Absorption spectroscopy was evaluated as a technique to monitor the metal organic chemical vapor deposition (MOCVD) process for forming YBa2Cu3O7-x superconducting coated conductors.Specifically, this study analyzed the feasibility of using absorption spectroscopy to monitor the MOCVD supply vapOr concentrations of the organic ligand 2,2,6,6-tetramethyl-3,5-heptanedionate (TMHD) metal chelates of barium, copper, and yttrium.Ba(TMHD)2, Cu(TMHD)2, and Y(TMHD)3 compounds have successfully been vaporized in the MOCVD processing technique to form high temperature superconducting coated conductors, a promising technology for wire fabrication.The absorption study of the barium, copper, and yttrium (TMHD) precursors was conducted in the ultraviolet wavelength region from 200nm to 400nm. To simulate theMOCVD precursor flows the Ba(TMHD)2, Cu(TMHD)2, and Y(TMHD)3 complexes were vaporized at vacuum pressures of (0.03-10)Torr. Spectral absorption scans of each precursor were conducted to examine potential measurement wavelengths for determining vapor concentrations of each precursor via Beer\u27s law.The experimental results show that under vacuum conditions the barium, copper,and yttrium (TMHD) precursors begin to vaporize between 90°C and 135°C, which are considerably lower vaporization temperatures than atmospheric thermal gravimetric analysis indicate. Additionally, complete vaporization of the copper and yttrium (TMHD)precursors occurred during rapid heating at temperatures between 145°C and 195°C and after heating at constant temperatures between 90°C and 125°C for approximately one hour,whereas the Ba(TMHD)2 precursor did not completely vaporize. At constant temperatures,near constant vaporization levels for each precursor were observed for extended periods of time. Detailed spectroscopic scans at stable vaporization conditions were conducted

DC-transport in superconducting point contacts: a full counting statistics view

We present a comprehensive theoretical analysis of the dc transport properties of superconducting point contacts. We determine the full counting statistics for these junctions, which allows us to calculate not only the current or the noise, but all the cumulants of the current distribution. We show how the knowledge of the statistics of charge transfer provides an unprecedented level of understanding of the different transport properties for a great variety of situations. We illustrate our results with the analysis of junctions between BCS superconductors, contacts between superconductors with pair-breaking mechanisms and short diffusive bridges. We also discuss the temperature dependence of the different cumulants and show the differences with normal contacts.Comment: revtex4, 20 pages, 15 figure

Full Counting Statistics of Superconductor--Normal-Metal Heterostructures

The article develops a powerful theoretical tool to obtain the full counting statistics. By a slight extension of the standard Keldysh method we can access immediately all correlation functions of the current operator. Embedded in a quantum generalization of the circuit theory of electronic transport, we are able to study the full counting statistics of a large class of two-terminal contacts and multi-terminal structures, containing superconductors and normal metals as elements. The practical use of the method is demonstrated in many examples.Comment: 35 pages, contribution to "Quantum Noise", ed. by Yu.V. Nazarov and Ya.M. Blanter, minor changes in text, references adde

Analytical and experimental investigations of low level acceleration measurement techniques

Construction techniques for accelerometer with low level threshold sensitivit

DEVELOPMENT OF MULTIPLE SAMPLE SOLID-STATE NMR PROBES FOR ANALYSIS OF PHARMACEUTICAL COMPOUNDS AND FORMULATIONS

Solid-state NMR spectroscopy (ssNMR) is an extremely powerful technique for the analysis of pharmaceutical dosage forms. A major limitation of ssNMR is the number of samples that can be analyzed in a given period of time. Development of three versions of probes that contain multiple magic angle spinning (MAS) modules for interleaved acquisition has been done, and each shows no loss in spectral quality compared to a standard probe. A prototype probe incorporating two MAS modules was first developed. This version is limited to being a two-module probe due to the large amounts of space required for the tuning elements, which are located next to the MAS modules. A new probe design incorporating coaxial transmission lines and smaller MAS modules has also been constructed. This probe allows for close proximity of the MAS modules (within 3 cm) and the capability of remote tuning and sample changing. This probe design can be easily scaled to incorporate more than two MAS modules, which is a limitation of the previous design. The number of modules that can be incorporated is only limited by the number of transmission lines that will fit in a cross-sectional diameter of the bore and the axial field length of the magnet. A third version addresses the main issues of length and linear actuation that the first generation probes have. So that the superconducting magnet can be left at "factory" height, a non-actuated probe that has the ability to collect two samples at a time has been constructed and tested. The radio frequency circuits have been isolated to such a degree that they do not dramatically affect the spectra of one another. Spectra of ssNMR standards: methylglutaric acid, hexamethylbenzene, and adamantane were acquired to show comparable performance of all multiple sample probe versions and conventional probes