Large-scale Explosion Research Articles

Explosive events in the early universe

Large-scale explosions, possibly the cumulative effects of supernovae, may have occurred in the early history of the Universe (10greater than or equal tozgreater than or equal to2). The observed metal abundances in evolved stars in giant ellipticals suggest that as much as 10$sup 51$ ergs per solar mass of metal- rich material might have been released. Alternatively, the energy output of any galaxy can be estimated at 5times10$sup 51$ ergs per present visual solar luminosity. Blast waves from such a large input of energy could heat and ionize an intergalactic medium (IGM) of closure density to a degree that would be consistent with the limits on both the 21-cm absorption in nearby radio sources and the L$alpha$ absorption in quasars. The bremsstrahlung radiation emitted by the ionized gas might explain the possible excess observed in the diffuse X-ray background below 1 keV. (AIP)

Coal dust explosions in a large-scale vertical tube apparatus

Considerable date exist on large-scale coal dust explosions, and it is convenient to establish from these results the validity of small-scale explosibility tests for industrial dusts. The explosibility of coal dust mixed with limestone and sodium chloride has been investigated in order to relate small-scale tests to full industrial scale. The efficiencies of limestone and sodium chloride in suppressing explosions in the tests and in a large-scale vertical tube were compared. The results for the coal/limestone mixtures were also in good agreement with those from experiments elsewhere in a large-scale mine gallery. The agreement indicated that information gained from the vertical tube would apply to a full-scale industrial plant. The minimum percentages of the diluents required to prevent explosions in the vertical tube have been compared with those calculated from heat balance equations based on the thermal properties of the dusts. Reasonable agreement was obtained for limestone dust. Consideration was also given to the dependence of the limestone requirement on the volatile content of the coal and the power of the ignition source. Sodium chloride was a better explosion suppressor than stone dust, and its efficiency was much greater than that predicted by calculations based on its thermal properties.

A POSSIBLE "SUPER-SUPERNOVA" REMNANT IN NGC 6946

Westerlund and Mathewson (1966) have presented rather convincing evidence that Constellation III of the Large Magellanic Cloud (Nail and Shapley 1953) is the result of a large-scale (super-supernova) explosion possibly of the type hypothesized by Shklovskii (1960). Hay ward (1964) has noted several similar formations in photographs of galaxies printed in the Hubble Atlas. This note describes a probable formation of this type in NGC 6946. Plate I shows two photographs of a section of the galaxy NGC 6946. One of the photographs (V) was taken on Kodak 103a-D emulsion with a Schott GG 11 filter; the other represents an Ha composite, made by subtracting a negative of the V plate from a plate taken on 103a-E emulsion with a Schott RG 1 filter. On the composite, Ha emission objects show up as black regions. In the center is the feature that appears to be similar to the SSN loop of the LMC. The notable features of this object are: that stars are arranged in a bright circular loop, 17 in diameter; that this loop shows evidence of being made up of two or perhaps three somewhat nonconcentric parts; that these loops are rich in extremely bright blue stars, readily resolved on blue plates with the 120-inch telescope; that the loops, bright in the continuum, are not rich in H n regions, as are other bright star clouds in the galaxy; that a small, bright H ii region, No. 33 in a catalog of Ha regions in NGC 6946 (Hodge 1966), can be seen at the center of the loop; and that a larger, faint H h region (No. 34 in the catalog) lies just outside the stellar loop. All of these features find their counterparts in the Constellation III features, identified by Westerlund and Mathewson as an SSN loop in the LMC. Figure 1 graphically compares them.

Fractionation Phenomena in Highly Radioactive Fall-Out Particles

Highly radioactive fallout particles were found throughout Japan following the series of large-scale nuclear test explosions carried out by the U.S.S.R. during Sept. and Oct., 1961. The radiochemical composition of these particles was determined by gamma -ray spectrometry. The composition of large particles was different from that of smaller particles. The extent of the fractionation effect on the composition of fallout particles was investigated. Data are presented on fractionation factors and fractionation observed in rain water samples collected in Nov. 1961. (C.H.)

Electron Microscopic Examination of Highly Radioactive Fail-Out Particles

MICROSCOPIC examination of highly radioactive fall-out particles, produced by the series of large-scale nuclear test explosions carried out during September and October 1961, revealed that although they were quite or nearly spherical, their surface states were different from particle to particle and some of them were much creased or had small spherical particles attached to their surface1. Electron microscopic examination followed by electron photomicrography has been carried out to examine their surface state in detail. A vacuum-evaporated silica film backed with evaporated carbon film was used for holding a sample particle. A small drop of benzene was put on the silica film which was supported on a 150 sheet mesh, then a sample particle which had been picked up by the tip of a fine needle was transferred into the drop seen under a microscope. The sample particle was left on the film after the drop evaporated out. Electron photomicrographs of four particles, A, B, C and Z, were taken. In Table 1 are given their diameters, radioactivities and fractionation factors for 141Ce + 144Ce (ref. 2). Fig. 1 (1,2,3) gives electron photomicrographs of particles A, B and C, respectively. Small particles adhered to the surface are thought to be fine fall-out particles which are micron size or smaller3. Fig. 1 (5) is a close-up of a part of particle C. The diameter of this small particle is about l.4µ.

High Speed Photography of Large Scale Explosion

High Speed Photography of Large Scale Explosion