424 research outputs found
A Summary and Analysis of NASA's Strategic Astrophysics Technology PCOS/COR Investments Since Program Inception
The NASA Strategic Astrophysics Technology (SAT) Program was established in 2009 as a new technology maturation program to fill the gap in the Technology Readiness Level (TRL) range from 3 to 6. Since the inception of the program, 47 tasks have been awarded under the auspices of the NASA Physics of the Cosmos (PCOS) Program in the areas of optics and detectors as well as lasers, electronics, and micro-thruster subsystems. In addition, 31 tasks have been awarded under the auspices of the NASA Cosmic Origins (COR) Program to develop optics, coatings, cooling subsystems, and detectors from the Far-IR to the Far-UV. We present the PCOS/COR portfolio distribution in terms of specific technology areas addressed and show an analysis of the rate and cost of TRL advancements. We present highlights of the infusion success stories that have emerged from the SAT maturation program as it relates to enabling future NASA astrophysics strategic missions. Finally, we present an outlook for future technology priorities for investment by the SAT Program
Accurate Visuomotor Control below the Perceptual Threshold of Size Discrimination
Background: Human resolution for object size is typically determined by psychophysical methods that are based on conscious perception. In contrast, grasping of the same objects might be less conscious. It is suggested that grasping is mediated by mechanisms other than those mediating conscious perception. In this study, we compared the visual resolution for object size of the visuomotor and the perceptual system. Methodology/Principal Findings: In Experiment 1, participants discriminated the size of pairs of objects once through perceptual judgments and once by grasping movements toward the objects. Notably, the actual size differences were set below the Just Noticeable Difference (JND). We found that grasping trajectories reflected the actual size differences between the objects regardless of the JND. This pattern was observed even in trials in which the perceptual judgments were erroneous. The results of an additional control experiment showed that these findings were not confounded by task demands. Participants were not aware, therefore, that their size discrimination via grasp was veridical. Conclusions/Significance: We conclude that human resolution is not fully tapped by perceptually determined thresholds
Relative abundances of cosmic ray nuclei B-C-N-O in the energy region from 10 GeV/n to 300 GeV/n. Results from ATIC-2 (the science flight of ATIC)
The ATIC balloon-borne experiment measures the energy spectra of elements
from H to Fe in primary cosmic rays from about 100 GeV to 100 TeV. ATIC is
comprised of a fully active bismuth germanate calorimeter, a carbon target with
embedded scintillator hodoscopes, and a silicon matrix that is used as the main
charge detector. The silicon matrix produces good charge resolution for protons
and helium but only partial resolution for heavier nuclei. In the present
paper, the charge resolution of ATIC was improved and backgrounds were reduced
in the region from Be to Si by using the upper layer of the scintillator
hodoscope as an additional charge detector. The flux ratios of nuclei B/C, C/O,
N/O in the energy region from about 10 GeV/nucleon to 300 GeV/nucleon obtained
from this high-resolution, high-quality charge spectra are presented, and
compared with existing theoretical predictions.Comment: 4 pages,2 figures, a paper for 30-th International Cosmic Rays
Conferenc
Beam test calibration of the balloon-borne imaging calorimeter for the CREAM experiment
CREAM (Cosmic Ray Energetics And Mass) is a multi-flight balloon mission
designed to collect direct data on the elemental composition and individual
energy spectra of cosmic rays. Two instrument suites have been built to be
flown alternately on a yearly base. The tungsten/Sci-Fi imaging calorimeter for
the second flight, scheduled for December 2005, was calibrated with electron
and proton beams at CERN. A calibration procedure based on the study of the
longitudinal shower profile is described and preliminary results of the beam
test are presented.Comment: 4 pages, 4 figures. To be published in the Proceedings of 29th
International Cosmic Ray Conference (ICRC 2005), Pune, India, August 3-10,
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Simulation of the ATIC-2 Silicon Matrix for Protons and Helium GCR Primaries at 0.3, 10, and 25 TeV/Nucleon
The energy deposition distribution for protons and helium galactic cosmic ray primaries at 0.3, 10, and 25 TeV/nucleon in the ATIC-2 silicon matrix detector are simulated with GEANT4. The GEANT3 geometrical model of ATIC developed by the University of Maryland was combined with a GEANT4 application developed for the Deep Space Test Bed (DSTB) detector package. The new code included relatively minor modifications to completely describe the ATIC materials and a more detailed model of the Silicon Matrix detector. For this analysis all particles were started as a unidirectional beam at a single point near the center of the Silicon Matrix front surface. The point was selected such that each primary passed through at least two of the overlapping silicon pixels
Cosmic-Ray Proton and Helium Spectra from the First CREAM Flight
Cosmic-ray proton and helium spectra have been measured with the
balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in
Antarctica in the 2004-2005 austral summer season. High-energy cosmic-ray data
were collected at an average altitude of ~38.5 km with an average atmospheric
overburden of ~3.9 g cm. Individual elements are clearly separated with
a charge resolution of ~0.15 e (in charge units) and ~0.2 e for protons and
helium nuclei, respectively. The measured spectra at the top of the atmosphere
are represented by power laws with a spectral index of -2.66 0.02 for
protons from 2.5 TeV to 250 TeV and -2.58 0.02 for helium nuclei from 630
GeV/nucleon to 63 TeV/nucleon. They are harder than previous measurements at a
few tens of GeV/nucleon. The helium flux is higher than that expected from the
extrapolation of the power law fitted to the lower-energy data. The relative
abundance of protons to helium nuclei is 9.1 0.5 for the range from 2.5
TeV/nucleon to 63 TeV/nucleon. This ratio is considerably smaller than the
previous measurements at a few tens of GeV/nucleon.Comment: 20 pages, 4 figure
Measurements of cosmic-ray energy spectra with the 2nd CREAM flight
During its second Antarctic flight, the CREAM (Cosmic Ray Energetics And
Mass) balloon experiment collected data for 28 days, measuring the charge and
the energy of cosmic rays (CR) with a redundant system of particle
identification and an imaging thin ionization calorimeter. Preliminary direct
measurements of the absolute intensities of individual CR nuclei are reported
in the elemental range from carbon to iron at very high energy.Comment: 4 pages, 3 figures, presented at XV International Symposium on Very
High Energy Cosmic Ray Interactions (ISVHECRI 2008
Elemental energy spectra of cosmic rays measured by CREAM-II
We present new measurements of the energy spectra of cosmic-ray (CR) nuclei
from the second flight of the balloon-borne experiment CREAM (Cosmic Ray
Energetics And Mass). The instrument (CREAM-II) was comprised of detectors
based on different techniques (Cherenkov light, specific ionization in
scintillators and silicon sensors) to provide a redundant charge identification
and a thin ionization calorimeter capable of measuring the energy of cosmic
rays up to several hundreds of TeV. The data analysis is described and the
individual energy spectra of C, O, Ne, Mg, Si and Fe are reported up to ~ 10^14
eV. The spectral shape looks nearly the same for all the primary elements and
can be expressed as a power law in energy E^{-2.66+/-0.04}. The nitrogen
absolute intensity in the energy range 100-800 GeV/n is also measured.Comment: 4 pages, 3 figures, presented at ICRC 2009, Lodz, Polan
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