SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Study considers problems encountered in using 4 pi-recoil counters for neutron spectra measurement. Emphasis is placed on calibration, shape discrimination, variation of W, the average energy loss per ion pair, and the effects of differentiation on the intrinsic counter resolution.
Proton recoil measurements of PuBe source neutron spectra
Utilization of elastically scattered recoil ions to measure solid state track detector registration characteristics and particle trajectory analysis
Laser quantum theoretical analysis, considering atomic thermal motion, photon emission and absorption induced recoil effects on lasing threshold and operating frequency
Proton recoil measurements of PuBe neutron source spectra, using pressurized hydrogen spherical proportional counter and liquid scintillator measurements
Horn and Von Oertzen (1967) have shown that tracks in mica are produced by an irradiation with 32-MeV O-16 ions. These tracks were attributed to K and Fe recoils produced by elastic scattering of the incident oxygen beam. In the present work an alternate explanation of their observations is provided. The measured characteristics of the tracks are shown to be compatible with theoretical predictions for production of tracks by inelastic (mostly compound nucleus) reactions with silicon and to be inconsistent with the previously proposed elastic scattering process. The possibility that the tracks are produced by contaminant ions in the beam cannot be ruled out.
S ions with a mean charge state of about 14+ and Cl ions with a mean charge state of 12+ were used to study Ne L-shell vacancy production. The ions caused copious production of NeII-NeVIII excited states with approximately 10 to the minus 18 sq cm cross sections. The induced recoil velocities might have application to a significantly higher resolution spectroscopy than is possible with beam-foil methods.
It is shown that the mass-polarization shift in the energy levels of 1sNL Rydberg states of helium contains a term of second order, in the ratio of the electron mass to that of the nucleus, that is independent of L. The derivation of this new recoil term, based on the method of Drachman (1986), is very simple. It yields a correction of significance for the calculation of absolute ionization energies.
The eccentricity and inclination acquired by a satellite during its recoil from a disk interior to the Roche limit are estimated. Possible implications for the early history of the Earth-Moon system are discussed.
Recent developments in numerical relativity have made it possible to follow reliably the coalescence of two black holes from near the innermost stable circular orbit to final ringdown. This opens up a wide variety of exciting astrophysical applications of these simulations. Chief among these is the net kick received when two unequal mass or spinning black holes merge. The magnitude of this kick has bearing on the production and growth of supermassive black holes during the epoch of structure formation, and on the retention of black holes in stellar clusters. Here we report the first accurate numerical calculation of this kick, for two nonspinning black holes in a 1.5:1 mass ratio, which is expected based on analytic considerations to give a significant fraction of the maximum possible recoil. We have performed multiple runs with different initial separations, orbital angular momenta, resolutions, extraction radii, and gauges. The full range of our kick speeds is 86-116 kilometers per second, and the most reliable runs give kicks between 86 and 97 kilometers per second. This is intermediate between the estimates from two recent post-Newtonian analyses and suggests that at redshifts z greater than 10, halos with masses less than 10(exp 9) M(sub SUN) will have difficulty retaining coalesced black holes after major mergers.
The fact that protons cause single-event effects (SEE) in most devices through production of light-ion recoils has led to attempts to bound heavy-ion SEE susceptibility through use of proton data. Although this may be a viable strategy for some devices and technologies, the data must be analyzed carefully and conservatively to avoid over-optimistic estimates of SEE performance. We examine the constraints that proton test data can impose on heavy-ion SEE susceptibility.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Molecular beam study of reaction of velocity selected potassium beam crossed with thermal iodine beam
Vibration sources are described for pneumatic hammers used in the mining industry (pick hammers), in boiler shops (riveting hammers), etc., bringing to light the fact that the principal vibration source is the variation in air pressure inside the cylinder. The present state of the art of vibration control of pneumatic hammers as it is practiced abroad, and the solutions adopted for this purpose, are discussed. A new type of pneumatic hammer with a low noise and vibration level is presented.
The sputtering of the lunar surface by the solar wind is examined as a possible mechanism of mass fractionation. Two distinct contributions to this mechanism are considered: (1) the tendency for a greater fraction of the heavier sputtered atoms to fall back to the surface under lunar gravity; and (2) mass-dependent kinetic effects that arise in the sputtering process itself. Calculations predict that delta (O-18) is approximately 5.6% while delta (Si-30) is about 3.6% and that oxygen is depleted in the outer regions of grains relative to the bulk composition. The results are in reasonable agreement with experiment, and one must conclude that mass fractionation by solar wind is an important phenomenon on the lunar surface.
Explore the source record for details and available documents.
A sequence of three Chandra X-ray Observatory High Resolution Camera images taken over a span of five years reveals arc-second-scale displacement of RX-J0822--4300, the stellar remnant near the center of the Puppis A supernova remnant. We measure its proper motion to be 0.16+/-0.02 arcsec/yr toward the west-southwest. At a distance of 2 kpc, this corresponds to a transverse space velocity of approx. 1500 km/s. This is the first case of a compact X-ray source with a directly measured proper motion. The space velocity is consistent with the explosion center inferred from proper motions of the oxygen-rich optical filaments, and confirms the idea that Puppis A resulted from an asymmetric explosion accompanied by a kick that imparted on the order of 3 x 10(exp 49) ergs of kinetic energy (some 3 percent of the supernova kinetic energy) to the stellar remnant. We will summarize this measurement and discuss possible mechanisms for producing such a violent kick. This research has been supported by NASA grant G04-5062X.