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The results from two surrogate reaction experiments using the STARS (Silicon Telescope Array for Reaction Studies) spectrometer are presented. The surrogate method involves measuring the particle and/or γ-ray decay probabilities of excited nuclei populated via a direct reaction. These probabilities can then be used to deduce neutron-induced reaction cross sections that lead to the same compound nuclei. In the first experiment STARS coupled to the GAMMASPHERE γ-ray spectrometer successfully reproduce surrogate (n,γ), (n,n′γ) and (n,2nγ) cross sections on 155,156Gd using 3He-induced reactions. In the second series of experiments an energetic deuteron beam from the ESTU tandem at the Wright Nuclear Structure Lab at Yale University was used to obtain the ratio of fission probabilities for 238U/236U and 237U/239U populated using the 236,238U(d,d′f) and 236,238U(d,pf) reactions. Results from these experiments are presented and the implications for the surrogate reaction technique are discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Cross-section measurements were made of prompt γ-ray production as a function of incident neutron energy on a 48Ti sample. Partial γ-ray cross sections for transitions in 45–48Ti, 44–48Sc, 42–45Ca, 41–44K, and 41–42Ar have been determined. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the LANSCE/WNR facility. The prompt-reaction γ rays were detected with the large-scale Compton-suppressed germanium array for neutron-induced excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The γ-ray excitation functions were converted to partial γ-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency, and neutron flux (monitored with an in-line fission chamber). The data will be presented for neutron energies between 1 to 250 MeV. These results are compared with model calculations that include compound nuclear and pre-equilibrium emission. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The potential for detecting rot in power poles with a radio frequency method was tested. Five pentachlorophenol-treated pole sections containing both sound and decayed wood were obtained from out-of-service power poles. Sections were conditioned in 12-percent equilibrium moisture content (EMC) conditions for 12 months prior to testing. Pole sections were scanned over their length by a laboratory prototype that applied 250, 500 and 2000 kHz radio frequency signals to opposed 1-inch diameter metal electrodes in contact with the pole surface. Each capacitor pair scanned each pole cross sectionally at multiple positions along pole longitudinal axis. Signal voltage attenuation and phase shift values for sound and decayed wood sections were recorded. Radio frequency signals for sound wood were compared to those of decayed wood. Radio frequency signals of 2000 kHz yielded the greatest difference in attenuation and phase shift response between sound and decayed wood. For even the best-performing 2000 kHz signal, evaluation of attenuation appeared to be an impractical means to differentiate sound from decayed wood. However, phase shift performed consistently in differentiating sound from decayed wood and, for signal frequencies of 2000 kHz and above, appears to have considerable potential for this purpose. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Five-fold differential cross sections (5DCS) for the electron-impact double ionization of the 3s electrons of magnesium have been measured in a high-impact-energy, high-momentum-transfer regime. These measurements fulfill two conditions necessary for the measurement of two-electron momentum densities, those being impulsive ionization and identification of the double-ionization mechanisms. The form of the measured cross sections provides strong evidence for two different impulsive two-step ionization mechanisms. Second Born calculations are in agreement with the experimental data. The implications for the measurement of two-electron momentum densities are discussed. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Electrical breakdown and recovery processes in water have been studied using electrical and nanosecond optical diagnostics. The breakdown electric field in submillimeter gaps with 200 ns voltage pulses applied has been measured as 1 MV/cm, the rate of current rise during breakdown reaches 4·10[sup 11] A/s. The switch recovery time is determined by expansion and decay of a vapor bubble. The experimental results, together with the results of a model with a percolative approach, provide design criteria for compact, high power, high repetition rate, liquid-switch pulse generators. [ABSTRACT FROM AUTHOR]

Radioactive Nuclear Beams (RNBs) are opening new regions of the nuclear landscape to nuclear structure studies. Early experiments with RNBs rely on reactions with large cross sections, inverse kinematics, and very efficient detector geometries in order to measure observables that are very sensitive to structural features. A Coulomb excitation experiment extracted the B(E2; 0[SUP+] → 2[SUP+) values of the neutron rich RNBs [SUP132,134]Te at the HRIBF with the GRAFIK through-well NaI(T1) detector. In addition, other q with RNBs, such as Coulomb excitation of octupole states and reorientation experiments, inelastic scattering, and single-particle transfer, will be discussed. [ABSTRACT FROM AUTHOR]

Electron impact double ionization with full determination of the kinematics of the collision, (e,3e), can, in principle, provide direct information on the correlated motion of the ejected electrons at the instant of ejection, provided that the mechanism of ejection is known. The symmetries of the observed double ionization cross sections in a variety of kinematic regimes can be used to experimentally investigate ejection mechanisms. The sensitivities of various experimental geometries and kinematic regimes to different ionization mechanisms are discussed in the context of the double ionization of the 3s electrons of magnesium. The practical implications for extracting information about electron correlation are examined. [ABSTRACT FROM AUTHOR]

The path and termination point for the rp-process above [sup 56]Ni is uncertain due to a lack of knowledge of nuclear properties, especially masses, near the proton drip line. To address this need we have begun a program to measure masses of nuclei along the rp-process pathway in the A∼60–80 region using β-γ coincidence spectroscopy. Results for [sup 71]Se are presented and a preliminary experiment for [sup 72]Br is described. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The g-factor of the first excited state of [SUP164]Yb was measured by perturbed gammagamma angular correlation in an external static magnetic field of 5.55 Tesla. The result, g(2[SUP+]1)=0.32(5), extends the systematics of g(2[SUP+]1) for Yb isotopes down to N=94, and is discussed in the framework of different models. [ABSTRACT FROM AUTHOR]

High spin states were smdied in [SUP140]Eu in a search for evidence of chiral structure. [ABSTRACT FROM AUTHOR]