Post-Band Merge Utilities Applied to Spitzer Pleiades Data

Band merging extracted point sources observed in multiple wavelength bands is generally done purely on the basis of positional information in order to avoid photometric biases. Automated merge decisions can be more optimal with better position estimation and more realistic modeling of positional estimation errors. Unfortunately, extraction software often does not provide the most accurate positional information possible, and so post-band merge utilities have been developed and implemented to refine both the source positions and the error modeling. Subsequent band merging of the refined detections improves the completeness and reliability of the multi-band source catalog. Application to Spitzer Space Telescope mapping observations of the Pleiades star cluster demonstrates some aspects of the improved band merging

Transient energy excitation in shortcuts to adiabaticity for the time dependent harmonic oscillator

There is recently a surge of interest to cut down the time it takes to change the state of a quantum system adiabatically. We study for the time-dependent harmonic oscillator the transient energy excitation in speed-up processes designed to reproduce the initial populations at some predetermined final frequency and time, providing lower bounds and examples. Implications for the limits imposed to the process times and for the principle of unattainability of the absolute zero, in a single expansion or in quantum refrigerator cycles, are drawn.Comment: 7 pages, 6 figure

Optimal merging of point sources extracted from Spitzer Space Telescope data in multiple infrared passbands versus simple general source association

For collating point-source flux measurements derived from multiple infrared passbands of Spitzer-Space-Telescope data – e.g., channels 1-4 of the Infrared Array Camera (IRAC) and channels 1-3 of the Multiband Imaging Pho- tometer for Spitzer (MIPS) – it is best to use the ‘bandmerge’ software developed at the Spitzer Science Center rather than the relatively simple method of general source association (GSA). The former method uses both source positions and positional uncertainties to form a chi-squared statistic that can be thresholded for optimal matching, while the latter method finds nearest neighbors across bands that fall within a user-specified radius of the primary source. Our assertion is supported by our study of completeness (C) vs. reliability (R) for the two methods, which involved MIPS-24/IRAC-1 matches in the SWIRE Chandra Deep Field South. Both methods can achieve C = 98%, but with R = 92.7% for GSA vs. R = 97.4% for bandmerge. With almost a factor of three lower in unreliability (1 − R), bandmerge is the clear winner of this comparison

Dynamic Spin-Polarized Resonant Tunneling in Magnetic Tunnel Junctions

Precisely engineered tunnel junctions exhibit a long sought effect that occurs when the energy of the electron is comparable to the potential energy of the tunneling barrier. The resistance of metal-insulator-metal tunnel junctions oscillates with an applied voltage when electrons that tunnel directly into the barrier's conduction band interfere upon reflection at the classical turning points: the insulator-metal interface, and the dynamic point where the incident electron energy equals the potential barrier inside the insulator. A model of tunneling between free electron bands using the exact solution of the Schroedinger equation for a trapezoidal tunnel barrier qualitatively agrees with experiment.Comment: 4pgs, 3 fig

Fluorine-plus-proton reactions

The properties of certain energy levels in O16, F19, and Ne20 have been studied by observations on the alpha particles and inelastic protons from the bombardment of fluorine by protons. A high-resolution magnetic analysis of the alpha-particle groups to the 2+ and 1- levels in O16 from the F19(p, α)O16* reaction failed to reveal any doublet structure in these known levels. The angular distributions of the alpha-particle groups to these levels did not indicate degeneracy with a 2- level, nor did a search for new excited levels in O16 up to 8.7-Mev excitation reveal a 2- level. These results are not in agreement with the alpha-particle model of the O16 nucleus which predicts a 2- state close in energy to the 2+ state. Angular distributions of the alpha particles were measured at proton bombarding energies of 873, 935, 1290, 1355, and 1381 kev. The distributions at 1355 kev indicated that the corresponding Ne20 resonance level at 14.16 Mev has spin 2 and odd parity. The spin and parity assignments previously found for the other levels were confirmed. A study of the inelastic proton groups from the F19(p, p′)F19* reaction gave 108.8±0.8 and 196.0±1.4 kev for the excitation energies of the two lowest excited levels of F19. The cross sections at the 1431-kev resonance for these groups in the center-of-mass system were 0.187±0.015 barn for the first group and 0.007 ±0.002 barn for the second group. At 1381 kev the cross section was 0.0427±0.0040 barn for protons to the second excited level. Angular distributions of the proton groups were measured and, in conjunction with other studies made in this laboratory, resulted in spin and parity assignments of ½- and 3/2+ for the first and second excited states of F19, respectively

Ariel 6 measurements of ultra-heavy cosmic ray fluxes in the region 34 or = Z or = 48

The Ariel VI satellite was launched by NASA on a Scout rocket on 3rd June 1979 from Wallops Island, Virginia, USA, into a near circular 625 km orbit inclined at 55 deg. It carried a spherical cosmic ray detector designed by a group from Bristol University. A spherical aluminum vessel of diameter 75 cm contains a gas scintillation mixture and a thin spherical shell of Pilot 425 plastic, and forms a single optical cavity viewed by 16 photomultipliers. Particle tracks through the detector may be characterized by their impact parameter p and by whether or not they pass through the cup of plastic scintillator placed between the sphere and the spacecraft body (referred to below as the Anti-Coincidence Detector or ACD). Individual particle charges are determined by separately measuring the gas scintillation and the Cerenkov emission from the plastic shell. This is possible because of the quite different distribution in time of these emissions

Architectural/Environmental Handbook for Extraterrestrial Design

Handbook on environmental and space utilization criteria for design of extraterrestrial manned spacecraft and shelter