Advanced optimal extraction for the Spitzer/IRS

We present new advances in the spectral extraction of point-like sources adapted to the Infrared Spectrograph onboard the Spitzer Space Telescope. For the first time, we created a super-sampled point spread function of the low-resolution modules. We describe how to use the point spread function to perform optimal extraction of a single source and of multiple sources within the slit. We also examine the case of the optimal extraction of one or several sources with a complex background. The new algorithms are gathered in a plugin called Adopt which is part of the SMART data analysis software.Comment: Accepted for publication in PAS

Recent passive density sensor effort at the Naval Ordnance Laboratory

Development of falling sphere for atmospheric density measurements onboard ship

Force and energy dissipation variations in non-contact atomic force spectroscopy on composite carbon nanotube systems

UHV dynamic force and energy dissipation spectroscopy in non-contact atomic force microscopy were used to probe specific interactions with composite systems formed by encapsulating inorganic compounds inside single-walled carbon nanotubes. It is found that forces due to nano-scale van der Waals interaction can be made to decrease by combining an Ag core and a carbon nanotube shell in the Ag@SWNT system. This specific behaviour was attributed to a significantly different effective dielectric function compared to the individual constituents, evaluated using a simple core-shell optical model. Energy dissipation measurements showed that by filling dissipation increases, explained here by softening of C-C bonds resulting in a more deformable nanotube cage. Thus, filled and unfilled nanotubes can be discriminated based on force and dissipation measurements. These findings have two different implications for potential applications: tuning the effective optical properties and tuning the interaction force for molecular absorption by appropriately choosing the filling with respect to the nanotube.Comment: 22 pages, 6 figure

Scaling and Further Tests of Heavy Meson Decay Constant Determinations from Nonrelativistic QCD

We present results for the B_s meson decay constant f_{B_s} from simulations at three lattice spacings in the range a^{-1}=1.1 to 2.6 GeV using NRQCD heavy quarks and clover light quarks in the quenched approximation. We study scaling of this quantity and check the consistency between mesons decaying from rest and from a state with nonzero spatial momentum. The cancellation of power law contributions that arise in the NRQCD formulation of heavy-light currents is discussed. On the coarsest lattice the D_s meson decay constant f_{D_s} is calculated. Our best values for the decay constants are given by f_{B_s} = 187(4)(4)(11)(2)(7)(6) MeV and f_{D_s} = 223(6)(31)(38)(23)(9)(^{+3}_{-1}) MeV.Comment: 29 pages with 7 postscript figures, improved error analysis, version to appear in Physical Review

New results on heavy hadron spectroscopy with NRQCD

We present results for the spectrum of b-bbar bound states in the quenched approximation for three different values of the lattice spacing. Results for spin-independent splittings are shown to have good scaling behaviour; spin-dependent splittings are more sensitive to discretisation effects. We discuss what needs to be done to match the experimental spectrum.Comment: 3 pages, contribution to Lattice'9

A Noisy Monte Carlo Algorithm

We propose a Monte Carlo algorithm to promote Kennedy and Kuti's linear accept/reject algorithm which accommodates unbiased stochastic estimates of the probability to an exact one. This is achieved by adopting the Metropolis accept/reject steps for both the dynamical and noise configurations. We test it on the five state model and obtain desirable results even for the case with large noise. We also discuss its application to lattice QCD with stochastically estimated fermion determinants.Comment: 10 pages, 1 tabl