Study on the effect of contamination on the performance of X-ray telescopes

Modifications were made to the X-ray reflectometer located at the Space Sciences Laboratory, Marshall Space Flight Center. One was an automatic drive for the Large Micrometer Head. This system, interfaced with the Hewlett Packard Computer System, is used to record data and provides the X-ray reflectometer with an automated data-taking capability. Using this system, a complete scatter curve can be obtained automatically. Previously, it was necessary to manually reset the system after recording for each data point in the scatter curve. The second modification provided an externally controlled electrical drive to move the microfocus X-ray source along its axis. With this modification, one can translate the X-ray source while it is operating to locate the position providing maximum count rate

A design study for the incorporation of aeroelastic capability into NASTRAN

Modifications and computational tasks required for aeroelastic capability in NASTRA

Quantitative multielement analysis using high energy particle bombardment

Charged particles ranging in energy from 0.8 to 4.0 MeV are used to induce resonant nuclear reactions, Coulomb excitation (gamma X-rays), and X-ray emission in both thick and thin targets. Quantitative analysis is possible for elements from Li to Pb in complex environmental samples, although the matrix can severely reduce the sensitivity. It is necessary to use a comparator technique for the gamma-rays, while for X-rays an internal standard can be used. A USGS standard rock is analyzed for a total of 28 elements. Water samples can be analyzed either by nebulizing the sample doped with Cs or Y onto a thin formvar film or by extracting the sample (with or without an internal standard) onto ion exchange resin which is pressed into a pellet

Emergency escape system uses self-braking mechanism on fixed cable

Slide-wire system with a twist level slide device incorporates automatic descent and braking for the safe and rapid evacuation of personnel from tall structures. This device is used on any tall structure that might require emergency evacuation. It is also used to transfer materials and equipment

Consistent Scenarios for Cosmic-Ray Excesses from Sommerfeld-Enhanced Dark Matter Annihilation

Anomalies in direct and indirect detection have motivated models of dark matter consisting of a multiplet of nearly-degenerate states, coupled by a new GeV-scale interaction. We perform a careful analysis of the thermal freezeout of dark matter annihilation in such a scenario. We compute the range of "boost factors" arising from Sommerfeld enhancement in the local halo for models which produce the correct relic density, and show the effect of including constraints on the saturated enhancement from the cosmic microwave background (CMB). We find that boost factors from Sommerfeld enhancement of up to ~800 are possible in the local halo. When the CMB bounds on the saturated enhancement are applied, the maximal boost factor is reduced to ~400 for 1-2 TeV dark matter and sub-GeV force carriers, but remains large enough to explain the observed Fermi and PAMELA electronic signals. We describe regions in the DM mass-boost factor plane where the cosmic ray data is well fit for a range of final states, and show that Sommerfeld enhancement alone is enough to provide the large annihilation cross sections required to fit the data, although for light mediator masses (less than ~200 MeV) there is tension with the CMB constraints in the absence of astrophysical boost factors from substructure. Additionally, we consider the circumstances under which WIMPonium formation is relevant and find for heavy WIMPs (greater than ~2 TeV) and soft-spectrum annihilation channels it can be an important consideration; we find regions with dark matter mass greater than 2.8 TeV that are consistent with the CMB bounds and have ~600-700 present-day boost factors.Comment: Related web application at http://astrometry.fas.harvard.edu/mvogelsb/sommerfeld . v2: added brief clarification regarding propagation parameters, plots now show effect of relaxing CMB bounds. 35 pages in JCAP format, 4 figures. Accepted for publication in JCA