Test-based thermal explosion model for HMX

We present a thermal explosion (cookoff) model for an HMX-based plastic bonded explosive (LX-10). The thermal–chemical–mechanical response of LX-10 is modeled based on the measurements from the scaled thermal explosion experiment (STEX) at the Lawrence Livermore National Laboratory. Confined LX-10 is heated at a rate of 1 °C/h until an explosion is observed. The modeled cookoff problem is simulated by the Arbitrarily Lagrangian–Eulerian hydrocode (ALE3D) that can handle a wide spectrum of time scales that vary from a structural to a high speed shock physics time scale. In addition to a comprehensive model for energetic material, the confinement material namely an AerMet 100 steel is modeled as a Steinberg–Guinan material with a Johnson–Cook failure model with a statistical failure distribution. By using the size distribution data from the fragmentation experiment, the metal fracture and fragmentation due to an explosion are modeled. The explosion temperature is predicted to within 1°. Calculated wall strain provides violence associated with the thermal explosion process and agrees favorably with the measured STEX data.     

Photothermal effects in passive fiber Bragg grating resonators

Photothermal effects in passive Fabry-Perot resonators are caused by the conversion of circulating optical energy into heat as a result of absorption. This results in thermal change in the resonator's optical path length, the round-trip phase, and hence the resonance condition. We describe a simplified dynamic numerical model for photothermal effects in passive fiber Bragg grating resonators and present results of their experimental observation.     

Iron pentacarbonyl: are the axial or the equatorial iron-carbon bonds longer in the gaseous molecule?

The structure of iron pentacarbonyl, Fe(CO)(5), was reinvestigated by gas-phase electron diffraction using an experimental rotational constant available from the literature as a constraint on the structural parameters. The study utilized a B3LYP/6-311+G(d) ab initio quadratic force field, scaled to fit observed infrared wavenumbers, from which were calculated corrections for the effects of vibrational averaging on distances and certain other quantities useful for the structural analysis. The results confirm that the equatorial Fe-C bonds are longer than the axial ones, an important difference with the structure in the crystal where the equatorial Fe-C bonds are the shorter. Some distance (r(g)/A) and vibrational amplitude (l(alpha)/A) parameter values with estimated 2sigma uncertainties based on assumption of D(3h) symmetry are [r(Fe-C)] = 1.829(2), r(Fe-C)(eq) - r(Fe-C)(ax) = 0.032(20), [r(C=O)] = 1.146(2), r(C=O)(eq) - r(C=O)(ax) = 0.006(27), r(Fe-C)(ax) = 1.810(16), r(Fe-C)(eq) = 1.842(11), r(C=O)(ax) = 1.142(23), r(C=O)(eq) = 1.149(16), l(Fe-C)(ax) = l(Fe-C)(eq) = 0.047(5), and l(C=O)(ax) = l(C=O)(eq) = 0.036(3).     

Experimental demonstration of a squeezing-enhanced power-recycled michelson interferometer for gravitational wave detection

Interferometric gravitational wave detectors are expected to be limited by shot noise at some frequencies. We experimentally demonstrate that a power recycled Michelson with squeezed light injected into the dark port can overcome this limit. An improvement in the signal-to-noise ratio of 2.3 dB is measured and locked stably for long periods of time. The configuration, control, and signal readout of our experiment are compatible with current gravitational wave detector designs. We consider the application of our system to long baseline interferometer designs such as LIGO.     

Squeezing flow of elastic liquids

The theoretical analysis is made of the relation between applied force and plate separation for squeezing flows of viscoelastic liquids between closely-spaced parallel disks. The lubrication approximation and the quasi-steady-state assumption are employed in the development. Elastic effects are incorporated through inclusion of normal stresses. Solutions are presented for liquids with power-law viscometric functions, and a numerical procedure is used for fluids having viscometric functions of arbitrary form. For fast and slow squeezing, calculated values of t_{$\text{1}\text{2}$}, the time required to squeeze out half the fluid, are found to agree with the constant force data of Leider [1,2].     

The atom-cavity system as a generator of quadrature squeezed states

This paper describes experiments with a coupled atom-cavity system generating quadrature squeezed states of light. A wide range of parameters was explored and a regime was found where a beam of laser light with significant power (0.17 mW) and good noise suppression (measured 18±3%, inferred 50±10%) was observed. An analysis of the exact phase of the noise suppression shows it to be a minimum uncertainty state with reduced noise in a combined amplitude/phase quadrature. The observations are in good qualitative agreement with a full quantum theory of squeezing in optical bistability.     

T=1, spin-dipole strength in40Ca

Spin-dipole strength in⁴⁰Ca has been studied by inelastic scattering of 500-MeV protons and the dipole response in⁴⁰Ca is compared with the spin-dipole data from the⁴⁰Ca(p, n) reaction and nonspin-dipole data from photonuclear studies.