Quality control of microelectronic wire bonds

Report evaluates ultrasonic bonding of small-diameter aluminum wire joined to ceramic substrates metalized with thin-film and thick-film gold. Quick testing technique for nondestructive location of poor wire bonds is also presented

Development of and dynamic studies concerning a cable boom system prototype

The conception of a cable boom system for a scientific spin stabilized satellite led to a flat cable stowed on a drum with a flexlead without conversion to avoid slip rings and to facilitate automatic restowage from any state of deployment. Some dynamic features of the extended cable boom and especially the comparison between round and flat cables were investigated in a phenomenological study using a test rig capable of inducing lateral, torsional and thermal cycling disturbances separately or in any combination

Final excitation energy of fission fragments

We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition according to a level density description with a transition from a constant-temperature regime to a Fermi-gas regime. Complete or partial excitation-energy sorting is found at energies well above the transition energy.Comment: 8 pages, 3 figure

Local support against gravity in magneto-turbulent fluids

Comparisons of the integrated thermal pressure support of gas against its gravitational potential energy lead to critical mass scales for gravitational instability such as the Jeans and the Bonnor-Ebert masses, which play an important role in analysis of many physical systems, including the heuristics of numerical simulations. In a strict theoretical sense, however, neither the Jeans nor the Bonnor-Ebert mass are meaningful when applied locally to substructure in a self-gravitating turbulent medium. For this reason, we investigate the local support by thermal pressure, turbulence, and magnetic fields against gravitational compression through an approach that is independent of these concepts. At the centre of our approach is the dynamical equation for the divergence of the velocity field. We carry out a statistical analysis of the source terms of the local compression rate (the negative time derivative of the divergence) for simulations of forced self-gravitating turbulence in periodic boxes with zero, weak, and moderately strong mean magnetic fields (measured by the averages of the magnetic and thermal pressures). We also consider the amplification of the magnetic field energy by shear and by compression. Thereby, we are able to demonstrate that the support against gravity is dominated by thermal pressure fluctuations, although magnetic pressure also yields a significant contribution. The net effect of turbulence in the highly supersonic regime, however, is to enhance compression rather than supporting overdense gas even if the vorticity is very high. This is incommensurate with the support of the highly dynamical substructures in magneto-turbulent fluids being determined by local virial equilibria of volume energies without surface stresses.Comment: 21 pages, 25 figures, revised version accepted for publication by MNRA

A Nearly Polar Orbit for the Extrasolar Hot Jupiter WASP-79b

We report the measurement of a spin-orbit misalignment for WASP-79b, a recently discovered, bloated transiting hot Jupiter from the WASP survey. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope. We have used the Rossiter-McLaughlin effect to determine the sky-projected spin-orbit angle to be lambda = -106+19-13 degrees. This result indicates a significant misalignment between the spin axis of the host star and the orbital plane of the planet -- the planet being in a nearly polar orbit. WASP-79 is consistent with other stars that have Teff > 6250K and host hot Jupiters in spin-orbit misalignment.Comment: 8 pages, 2 figures, in press ApJL (accepted 2 August 2013

High Accuracy Near-infrared Imaging Polarimetry with NICMOS

The findings of a nine orbit calibration plan carried out during HST Cycle 15, to fully determine the NICMOS camera 2 (2.0 micron) polarization calibration to high accuracy, are reported. Recently Ueta et al. and Batcheldor et al. have suggested that NICMOS possesses a residual instrumental polarization at a level of 1.2-1.5%. This would completely inhibit the data reduction in a number of GO programs, and hamper the ability of the instrument to perform high accuracy polarimetry. We obtained polarimetric calibration observations of three polarimetric standards at three spacecraft roll angles separated by ~60deg. Combined with archival data, these observations were used to characterize the residual instrumental polarization in order for NICMOS to reach its full potential of accurate imaging polarimetry at p~1%. Using these data, we place an 0.6% upper limit on the instrumental polarization and calculate values of the parallel transmission coefficients that reproduce the ground-based results for the polarimetric standards. The uncertainties associated with the parallel transmission coefficients, a result of the photometric repeatability of the observations, are seen to dominate the accuracy of p and theta. However, the updated coefficients do allow imaging polarimetry of targets with p~1.0% at an accuracy of +/-0.6% and +/-15deg. This work enables a new caliber of science with HST.Comment: 13 pages, 9 figures, PASP accepte

Sun direction detection system

One of the detectors is an illumination detector consisting of two spaced apart elongated strips with a strip of cadmium sulphide (Cds) deposited therebetween. Whenever the line image impinges the CdS strip, the resistance between the two other strips is relatively low, while being high when the line image is outside the field of view of the illumination detector. Also included is a sun angle detector which consists of a vapor deposited resistor strip connected at one end to plus 10v and at the other end to minus 10v. Spaced apart from the resistor strip is an elongated strip of low resistance material acting as an output strip, with a CdS strip between the two strips. When the line image is within the field of view of the sun angle detector, the output voltage at the output strip depends on the position of the line image across the sun angle detector