Nondestructive assessment of penetration of electron-beam welds

Empirical method correlates penetration of an electron-beam weld with external measurements of the weld. Empirical polygon accurately confirms full-penetration welds while a second, larger polygon provides for penetration of welds near the tip

Letter from T. Harmon to Governor Washburn recommending Reverend J.N. Marsh for appointment as chaplain of 8th Maine Regiment, August 30, 1861

https://digitalmaine.com/adj_gen_corr_town_belfast/1005/thumbnail.jp

Induced radioactivity in LDEF components

A systematic study of the induced radioactivity of the Long Duration Exposure Facility (LDEF) is being carried out in order to gather information about the low earth orbit radiation environment and its effects on materials. The large mass of the LDEF spacecraft, its stabilized configuration, and long mission duration have presented an opportunity to determine space radiation-induced radioactivities with a precision not possible before. Data presented include preliminary activities for steel and aluminum structural samples, and activation subexperiment foils. Effects seen in the data show a clear indication of the trapped proton anisotropy in the South Atlantic Anomaly and suggest contributions from different sources of external radiation fluxes

Discovery of Pulsed X-ray Emission from the SMC Transient RX J0117.6-7330

We report on the detection of pulsed, broad-band, X-ray emission from the transient source RX J0117.6-7330. The pulse period of 22 seconds is detected by the ROSAT/PSPC instrument in a 1992 Sep 30 - Oct 2 observation and by the CGRO/BATSE instrument during the same epoch. Hard X-ray pulsations are detectable by BATSE for approximately 100 days surrounding the ROSAT observation (1992 Aug 28 - Dec 8). The total directly measured X-ray luminosity during the ROSAT observation is 1.0E38 (d/60 kpc)^2 ergs s-1. The pulse frequency increases rapidly during the outburst, with a peak spin-up rate of 1.2E-10 Hz s-1 and a total frequency change 1.8%. The pulsed percentage is 11.3% from 0.1-2.5 keV, increasing to at least 78% in the 20-70 keV band. These results establish RX J0117.6-7330 as a transient Be binary system.Comment: 17 pages, Latex, aasms, accepted for publication in ApJ Letter

Induced activation study of LDEF

Analysis of the induced radioactivity of the Long Duration Exposure Facility (LDEF) is continuing with extraction of specific activities for various spacecraft materials. Data and results of activation measurements from eight facilities are being collected for interpretation at Eastern Kentucky University and NASA/Marshall Space Flight Center. The major activation mechanism in LDEF components is the proton flux in the South Atlantic Anomaly (SAA). This flux is highly anisotropic, and could be sampled by taking advantage of the gravity-gradient stabilization of the LDEF. The directionally-dependent activation due to these protons was clearly observed in the data from aluminum experiment tray clamps (reaction product Na-22), steel trunnions (reaction product Mn-54 and others) and is also indicated by the presence of a variety of nuclides in other materials. A secondary production mechanism, thermal neutron capture, was observed in cobalt, indium, and tantalum, which are known to have large capture cross sections. Experiments containing samples of these metals and significant amounts of thermalizing low atomic number (Z) material showed clear evidence of enhanced activation of Co-60, In-114m, and Ta-182. Other mechanisms which activate spacecraft material that are not as easily separable from SAA proton activation, such as galactic proton bombardment and secondary production by fast neutrons, are being investigated by comparison to radiation environmental calculations. Deviations from one-dimensional radiation models indicate that these mechanisms are more important at greater shielding depths. The current status of the induced radioactivity measurements as of mid-year 1992 are reviewed. Specific activities for a number of materials which show SAA effects and thermal neutron capture are presented. The results for consistency by combining data from the participating institutions is also examined

Collection, analysis, and archival of LDEF activation data

The study of the induced radioactivity of samples intentionally placed aboard the Long Duration Exposure Facility (LDEF) and samples obtained from the LDEF structure is reviewed. The eight laboratories involved in the gamma-ray counting are listed and the scientists and the associated counting facilities are described. Presently, most of the gamma-ray counting has been completed and the spectra are being analyzed and corrected for efficiency and self absorption. The acquired spectra are being collected at Eastern Kentucky University for future reference. The results of these analyses are being compiled and reviewed for possible inconsistencies as well as for comparison with model calculations. These model calculations are being revised to include the changes in trapped-proton flux caused by the onset of the period of maximum solar activity and the rapidly decreasing spacecraft orbit. Tentative plans are given for the storage of the approximately 1000 gamma-ray spectra acquired in this study and the related experimental data

The interactions of atmospheric cosmogenic radionuclides with spacecraft surfaces

The discovery of the cosmogenic radionuclide Be-7 on the front surface of the Long Duration Exposure Facility (LDEF) spacecraft has opened opportunities to investigate new phenomena in several disciplines of space science. The experiments performed for this work show that the Be-7 results only if the source of the isotope is the atmosphere through which the spacecraft passed. We should expect that the uptake of beryllium in such circumstances will depend on the chemical form of the Be and the chemical nature of the substrate. It was found that the observed concentration of Be-7 does, in fact, differ between metal surfaces and organic surfaces such as PTFE (teflon). It is noted, however, that: (1) organic surfaces, even PTFE, are etched by the atomic oxygen found under these orbital conditions, and (2) the relative velocity of the species is 8 km(exp -1)s relative to the surface and the interaction chemistry and physics may differ from the norm. The Be-7 is formed by spallation of O and N nuclei under cosmic ray proton bombardment. The principal source region is at altitudes of 12-15 km. While very small quantities are produced above 300 km, the amount measured on the LDEF was 3 to 4 orders of magnitude higher than expected from production at orbital altitude. The most reasonable explanation is that Be-7 is rapidly transported from low altitudes by some unknown mechanism. The process must take place on a time scale similar to the half-life of the isotope (53 days). Many other isotopes are produced by cosmic ray reactions, and some of these are suited to measurement by the extremely sensitive methods of accelerator mass spectrometry. A program was initiated to search for these isotopes and it is hoped that such studies will provide new methods for studying mixing in the upper atmosphere

An Increasingly Negative Outlook: How Income Inequality Affects Personal Consumption Expenditures

This paper analyzes the effects of income inequality on real personal consumption expenditures (RPCE) within the United States. At first glance, income inequality and RPCE have both risen over time. This paper examines whether income inequality actually causes growth in RPCE. We created a time-series model explaining RPCE with six explanatory variables and data spanning 37 years. Using this model, we were able to determine that income inequality has a statistically significant effect on RPCE. This effect becomes increasingly negative when the distribution of income becomes less equal and there is growth in real income. Thus, our results refute the possibility that income inequality has a positive effect on RPCE

The Orbital Light Curve of Aquila X-1

We obtained R- and I-band CCD photometry of the soft X-ray transient/neutron- star binary Aql X-1 in 1998 June while it was at quiescence. We find that its light curve is dominated by ellipsoidal variations, although the ellipsoidal variations are severely distorted and have unequal maxima. After we correct for the contaminating flux from a field star located only 0.46" away, the peak-to-peak amplitude of the modulation is ~0.25 mag in the R band, which requires the orbital inclination to be greater than 36 degrees. The orbital period we measure is consistent with the 18.95 h period measured by Chevalier & Ilovaisky (1998). During its outbursts the light curve of Aql X-1 becomes single humped. The outburst light curve observed by Garcia et al. (1999) agrees in phase with our quiescent light curve. We show that the single humped variation is caused by a ``reflection effect,'' that is, by heating of the side of the secondary star facing towards the neutron star.Comment: 18 manuscript pages, 7 figures; accepted by A