Alpha-decay widths in 20Ne

The α-decay of several unbound levels in ²⁰Ne has been studied by ¹⁶O(α, α) elastic and inelastic scattering. A narrow resonance, Γ_c.m. = 13±4 eV, with J^π = 5^? was found at $\text{E}{}_{\mathrm{<mtext>x</mtext>}}\text{(}{}^{20}\text{Ne}\text{) = 8.451±0.005}\text{MeV}$ and is associated with the lowest K = 2^? quasirotational band. Several new, narrow resonances were found between E_x = 16.0?18.4 MeV. Reduced α-decay widths have been obtained for the lowest K = 0⁺, 2^? and 0^?bands. For states described predominantly by the (8, 2) representation of SU(3) we note a reduction of the reduced widths with increasing spin. Reduced widths of positive parity bands are reviewed.     

Average g-factors for high-spin states in 78Kr

Inverse reactions of ^{63, 65}Cu beams on ^{18, 16}O targets have been used to populate states of ⁷⁸Kr by fusion-evaporation reactions. The excited nuclei recoiled at high velocity v/c ≈ 7 % through a polarized iron (⁵⁴Fe) layer and were stopped in a copper layer. During the period in iron, 0.05–0.65 ps, the nuclei were subjected to the intense transient magnetic field (initially ～ 3500 T). The resulting precession of the high-spin nuclear states populated during this time was determined by measuring the time integral rotation angle of the discrete γ-ray transitions at low spin.The average g-factor at low spin 2 ≦ J ≦ 8 compared to that at higher spin 8 ≦ J ≦ 12 in ⁷⁸Kr was found to be identical within the experimental uncertainties of ～ 15 %. This result implies that either there are no rotational alignment effects at the backbend in ⁷⁸Kr or more plausibly, proton (g ≈ 1) and neutron (g ≈ 0) aligned bands are equally competitive and both populated in the reaction. It is then likely that the resulting g-factor represents an average over many populated proton and neutron aligned bands.     

Initial-state distortion and final-state interactions in the 2H(3He, 3He p)n and 2H(3He, 3H p)p reactions

The predictions of two fully antisymmetrized reaction theories (DWBA and PWBA-FSI) are compared with absolute coincidence cross sections for the ²H(³He, ³He p)n and ²H(³He, ³H p)p reactions exhibiting final-state interactions (FSI) and quasi-elastic scattering (QES) both with and without charge exchange. The DWBA theory takes into account both the initial ³He-d and the final N-N interactions, while the PWBA-FSI theory includes only the latter. New QES data at E_He = 35.9 MeV, as well as previously reported 26.8 and 35.9 MeV data, are fitted. The DWBA theory gives good fits, both in shape and magnitude, to spectra showing N-N final-state interactions but gives somewhat poorer fits to QES spectra whose predicted magnitudes are two to ten times too large. The PWBA-FSI theory always predicts cross sections that are too large; however the predicted shapes are about as good as those from the DWBA. The initial-state interaction is shown to affect both the width and position of QES peaks from these reactions.     

A 22-kHz multibit switched-capacitor sigma-delta D/A converter with92 dB dynamic range

A time- and capacitor-multiplexing technique for use in a highly linear switched-capacitor multibit DAC in sigma-delta data converters is presented. The technique uses subintervals in the sample clock to deliver multiple charge packets to holding capacitors. It avoids distortion effects caused by mismatched capacitors and finite opamp gain. A five-level switched-capacitor DAC using the proposed technique was designed as part of an audio-band multibit sigma-delta D/A converter that achieved a dynamic range of 92 dB and a THD of -93 dB with a low oversampling ratio of 32. No trimming, calibration, or dynamic matching scheme was required. The five-level SC DAC has been fabricated in a 2-μm CMOS process, and testing confirmed the anticipated theoretical results     

Free-volume interpretations of self-diffusion in ternary solutions: n-Paraffin-hexafluorobenzene-cis-4-polybutadiene

Self-diffusion of both diluents in the systems n-paraffin + hexafluorobenzene + cis-4-polybutadiene (paraffin = dodecane or hexatriacontane) has been measured at 80°C as function of both concentrations, using field-gradient spin-echo techniques (¹H and ¹⁹F NMR). The data follow the free-volume model in the form of the Fujita-Doolittle equation, or the Vrentas-Duda theory, extended to apply to ternary systems. It is found that the polymer molecular jumping segments are roughly equal in size to the diluent molecules or their jumping segments.     

One-third terabit/s transmission through 150 km ofdispersion-managed fiber

340 Gb/s (seventeen 20-Gb/s 2³¹-1 PRBS NRZ channels) were transmitted through 150 km of fiber with 50 km amplifier spacing. Chromatic dispersion penalties and four-photon mixing effects were minimized by dispersion management