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In this work we report the most recent high-temperature long-term reliability results of the 600 V/14 A, 4H-SiC vertical-channel junction field-effect transistors (VJFETs). Two groups (A and B) devices were subjected to different thermal and electrical stresses. One device (Group A) reached 12,000 hours of continuous switching without a single failure. Four devices in Group A were thermally stressed at 250 °C over 4,670 hours in air, for which standard deviation of the specific on-resistance (RONSP) in linear region at gate bias (VGS) of 3 V were < 4.1% throughout the entire duration time. The off-state characteristics were evaluated by high temperature reverse bias (HTRB) tests. Three devices (Group A) were biased at 50% rated BVDS at 250 °C for 2,278 hours. A higher reverse bias at 80 % rated BVDS was then applied to 14 devices (group B) at 200 °C for 1,000 hours. Variations of the leakage current were negligible throughout the entire HTRB test for all tested devices.

Recently, there has been a rapid growth in the use of 3D multi-modal correlative imaging for studies of the human brain. Regional cerebral blood flow (CBF) changes indicate brain areas involved in stimulus processing. These focal changes are often too small ( >

We have carried out a partial-wave analysis of amalgamated pion-nucleon scattering data at 35 momenta in the range 0.429-1.995 GeV/c. At each momentum, a large set of fits was obtained, with the amplitude represented as the sum of a fixed background and the fitted terms of an accelerated convergence expansion. The effects of discrete and continuum ambiguities were separated by special statistical and numerical techniques which sort the fits into clusters. Dispersion relations on selected curves within the kinematical region for physical scattering were used to resolve the ambiguities and to derive constraints. These constraints, which ensure that the fitted amplitudes have a relatively smooth energy dependence consistent with analyticity, were used iteratively to arrive at a unique set of amplitudes which fit the scattering data throughout the energy region studied.

We have analyzed K+p cross-section and polarization data in the momentum range 0.78–2.53 GeV/c. Single energy fits were made using an ACE parametrization which had no cutoff in J, was analytic and had Regge-asymptotic behavior in the cut cos θ plane, and contained explicit contributions from P, ϱ, A2, Λ, Σ, and low-mass di-pion exchange. Direct channel analyticity constraints were imposed by a partial-wave dispersion relation interpolation procedure, fitting expansions in regulated-norm optimal bases to each partial wave which entered as a search parameter in the single energy fits. Output from these two programs was then used for a simultaneous fit by a linearized least squares program which provided input for another iterative fitting cycle. We find no strong evidence for the existence of exotic resonances. The method of analytic smoothing, in comparison with “shortest path” methods, is found to allow more significant threshold structure to appear in the amplitudes.

We present a series of numerical and statistical techniques for interpolating and combining (''amalgamating'') data from meson-nucleon scattering experiments. These techniques have been extensively applied to ..pi..p elastic and charge-exchange differential-cross-section and polarization data in the resonance region. The amalgamation is done by fitting a momentum- and angle-dependent interpolating surface to the data over a moderately narrow momentum range, typically approx.150 MeV/c, using the interpolating surface to shift data in a narrower central momentum region into fixed angular bins at a predetermined central momentum, and then statistically combining the data in each bin. The fitting procedure takes into account normalization errors, momentum calibration errors, momentum resolution, electromagnetic corrections, threshold structure, and inconsistencies among the data. The full covariance matrix of the amalgamated data is calculated, including contributions of statistical error, systematic error, and interpolation error. Techniques are presented for extracting from the covariance matrix information on the collective statistical fluctuations which correlate the errors of the amalgamated data. These fluctuations are described in terms of ''correlation vectors'' which facilitate the use of the amalgamated data as input for resonance-region phenomenology.

We report pion-nucleon partial-wave amplitudes obtained from analysis of scattering data at pion laboratory momenta from 0.42 to 2.0 GeV/c. These partial-wave amplitudes have been analyzed using modified Breit-Wigner, coupled-channel parametrizations. The resulting resonances and their parameters are tabulated.

A series of MoO 2 L 2 (L = ) complexes has been examined which exhibit activity as catalysts for the epoxidation of ethylene by t -butyl hydroperoxide. Improvements in selectivity and reproducibility for these catalysts have been shown to result from the addition of cyclohexene oxide to the reaction mixture. A mechanism which invokes dissociation of an ligand is suggested.

We show that the inclusion of noncollinear gluon bremsstrahlung is essential in a quantum-chromodynamic (QCD) description of large transverse energy events in hadron-hadron collisions. Recent data from CERN and Fermilab for both large and small aperture energy triggers give indirect experimental support for QCD and for gluon bremsstrahlung effects.

We have analyzed data on K+p elastic scattering at 21 momenta covering the range 0.5–2.5 GeV/c. We present results of three phase shift analyses. One of these is an energy independent accelerated convergence expansion (ACE) analysis in which high partial waves are included through use of conformal mapping as suggested by analytic approximation theory. The other two are an energy independent and an energy smoothed conventional analysis. The ACE method gave, with the same number of parameters, a 20% average improvement in x2 as well as more unique phase shift solutions. The high partial waves gave significant contributions to total and inelastic cross sections. The ACE method is also sensitive to the value of gΛΣ2 = gKΛN2 + gKΣN2; we have obtained the value gΛΣ2 = 15.2 ± 2.3.

A compilation of current high energy physics experiments is presented, including in the tables the various experimental parameters as well as the spokesmen and institutions. (JFP)

This is the fourth edition of our compilation of current high energy physics experiments. It is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), the Institute for Nuclear Study, Tokyo (INS), KEK, Serpukhov (SERP), and SLAC. The compilation includes summaries of all high energy physics experiments at the above laboratories that (1) were approved (and not subsequently withdrawn) before about April 1981, and (2) had not completed taking of data by 1 January 1977. We emphasize that only approved experiments are included.

A critical tabulation of observed spectral lines below 2000 angstroms has been prepared from the published literature up to July 1978. It is intended principally as an aid to those physicists and astronomers who deal with the spectra of highly stripped atoms. This report includes the first 18 elements, from hydrogen (including deuterium) through argon. The tabulation is divided into two main sections: the spectrum lines by spectrum, and a finding list. The entries for each element give the ionization species, ground state term, and ionization potential, as well as the best values of vacuum wavelength, intensity, and classification. A list of the pertinent references is appended at the end.

All the published atomic emission lines contained in the literature up to January 1959, are presented. Each line of data contains the vacuum wavelength in Angstroms, the element and spectroscopic notation for ionization the intensity, and reference numbers which refer to the list of references at the end of the report. Lists of intense lines arranged by ions, lines arranged by element, and binding lists are included. The intensities given in the tables are those published for spark sources. (W.D.M)