Engineering topics

Waddington, C. J.

Publications and source records attributed to Waddington, C. J..

At least 55 records · Page 3

NASA NTRS1983

The propagation of ultraheavy cosmic ray nuclei

The propagation of ultraheavy cosmic ray nuclei (Z greater than 30) has been studied using a model based on the leaky-box formalism. This model has been used to examine the possible composition of the source, the path length distribution, and the mean escape length of the confinement region. Various abundance ratios have been found that have a sensitive dependence on one or more of these factors. Comparison of the theoretical values of these ratios with published data suggests that the source composition is similar to that of solar system matter, but that in the Pt-Pb region, enrichment in material produced by the r-process cannot be ruled out. Data for the secondary-to-primary ratio (Ru-44 - Cd-48)/(Sn-50 - Ba-56) show the presence of significantly more secondaries than are predicted, even when a truncated path length distribution is used in the model.

Brewster, N. R.↗

NASA NTRS1983

Cosmic ray elemental abundances for Z = 26-42 measured on HEAO-3

An analysis is presented of 454 days of data from the Heavy Nuclei Experiment aboard the HEAO-3 satellite using an improved charge estimation algorithm is presented. A more precise normalization of Z = 32-42 abundances relative to iron is obtained, and more accurate detector response maps are used to recognize and reject a small class of events which was previously misidentified. The resulting abundances are in generally good agreement with solar system abundances with the first ionization potential (FIP) and with the Cameron solar system r-process (1982) with and without an applied FIP bias. The simplest interpretation of the results is that the cosmic ray source has solar system abundances modified by an FIP and/or volatility-dependent bias.

Binns, W. R.↗

NASA NTRS1983

Cosmic-ray abundances of the even charge elements from Sn-50 to Ce-58 measured on HEAO-3

Elements with even atomic number (Z) in the interval Z = 50-58 have been resolved in the cosmic radiation using the Heavy Nuclei Experiment on the HEAO-3 satellite. The observation that Sn-50 and Ba-56 are more abundant than Te-52 and Xe-54 indicates a substantial s-process contribution to the cosmic ray source. A significant abundance of Ce-58 provides further support for this finding.

Stone, E. C.↗

NASA NTRS1983

The cosmic ray abundances of the platinum-lead elements as measured on HEAO-3

The relative abundances of elements in the charge ranges of Z = 75-79 (platinum) and Z = 80-83 (lead) should be a sensitive indication of the contributions of the r- and s-processes in nucleosynthesis. Data from the HEAO 3 Heavy Nuclei Experiment are used to establish abundances, relative to iron, of these elements in the cosmic radiation, as well as the ratio of 'secondary' elements, in the Z = 62-74 range, to the primary lead-platinum elements. These results appear to suggest that either the source abundances are deficient in s-process elements or that they are not organized solely by first ionization potential. In addition, present propagation models can adequately represent the relative abundances of primary and secondary elements.

Fixsen, D. J.↗

NASA NTRS1983

Energy spectra of ultraheavy cosmic rays - Results from HEAO-3

The HEAO-3 Heavy Nuclei Experiment measures cosmic-ray energy directly in the interval 400 to about 1200 MeV/amu. Geomagnetic cutoffs can also be derived up to about 15 GV. Preliminary rigidity spectra of various ultraheavy cosmic-ray elements relative to iron are presented.

Israel, M. H.↗

NASA NTRS1983

Interactions of 200 GeV gold nuclei in light elements

Total charge-changing cross sections and partial cross-sections for interactions of 200 GeV Au-197 nuclei incident on carbon and polyethylene (CH2) targets have been measured during a calibration of the HEAO-3 Heavy Nuclei Experiment. From these, the total and partial cross-sections for Au-197 incident on hydrogen are inferred. The effects of using these cross-sections in one model of cosmic ray propagation are illustrated. Comparisons to predictions using semi-empirical formulas are shown.

Brewster, N. R.↗

NASA NTRS1983

Abundances of 'secondary' elements among the ultraheavy cosmic rays - Results from HEAO-3

The HEAO-3 Heavy Nuclei Experiment has measured elemental abundances of ultraheavy cosmic rays near earth. The elements with atomic number (Z) in the intervals Z = 44-48 and Z = 62-74 arriving at earth are expected to have significant secondary components. However, their source abundances are unlikely to be low enough to warrant treating them as pure secondaries. The present results are consistent with solar system abundances modified for first ionization potential with possibly some enhancement of the r to s ratio.

Klarmann, J.↗

NASA NTRS1982

The abundance of the actinides in the cosmic radiation as measured on HEAO 3

The HEAO 3 detector of heavy cosmic-ray nuclei has observed one possible actinide nucleus and some 100 nuclei of the platinum-lead group of elements. The resulting upper limit of 3% for the abundance ratio of actinides to platinum-lead nuclides is significantly lower than previous results from other observations. This new limit is inconsistent with freshly synthesized, pure r-process sources for cosmic-ray nuclei in this charge interval but is consistent with a source having a composition similar to the solar system, or to aged r-process material. We observe no events with a charge greater than 96.

Binns, W. R.↗

NASA NTRS1982

Confirmation of the anomalous behavior of energetic nuclear fragments

Cosmic-ray nuclei have been observed to produce 2072 secondary fragments in nuclear interactions detected in nuclear emulsions. These fragments produce 557 further interactions. Previous reports that these secondary nuclei show anomalously short mean free paths near their point of origin are confirmed. This effect can be interpreted as being due to all fragments having cross sections about twice normal for some 10 to the -10 sec after creation, or to a small fraction having cross sections an order of magnitude greater than normal.

Barber, H. B.↗

NASA NTRS1982

Abundances of cosmic ray nuclei heavier than 50 Sn

Preliminary results are reported from 430 days of exposure of the heavy nuclei experiment on the HEAO-3 spacecraft. These results are confined to the heavy nuclei with Z equal to or greater than 50 and emphasize the conclusions obtained on the relative numbers of actinides and heavy stable elements in the lead-platinum region. The extreme paucity of actinides found is inconsistent with the predictions of a cosmic ray source that is highly enriched in r-process material, but quite consistent with a source whose composition is similar to that of normal solar system material. An upper limit, at the 95 percent confidence level, is placed in the ratio of nuclei with Z equal to or greater than 88/(Z in the range from 74 to 87) of 0.03.

Waddington, C. J.↗

NASA NTRS1982

The propagation of UH-nuclei

A propagation model based on either a leaky box or a slab pathlength distribution and using the currently accepted nuclear parameters has been constructed for the charge range from 26 to 83. The predictions of this model have been examined to identify characteristic features in the observed charge spectrum capable of discriminating between various possible source compositions and different pathlength distributions.

Brewster, N. R.↗

NASA NTRS1982

Fragmentation of iron nuclei

During 1980 a modified version of our cosmic ray isotope detector was calibrated at the Bevalac. The fragmentation of iron ions in polyethylene (CH2) and Lucite (O5H8O2) has been studied at beam energies of 710 MeV/nuc and 1050 MeV/nuc. The total and partial charge changing cross-sections for the 1050 MeV/nuc beam (an average of 940 MeV/nuc in the target) are reported here and compared with other reported values.

Poferl-Kertzman, M.↗

NASA NTRS1982

The characteristics of particles emitted in energetic nucleus-nucleus interactions

The analysis of the interactions of heavy cosmic ray nuclei in nuclear emulsion exposed over Texas is continued, with 500 interactions of nuclei of E greater than 1.5 GeV/nucleon added. In this paper the experimental data correlating meson production with fragmentation of the projectile and target nuclei are given. These data, combined with earlier results, are also used to reexamine the problem of the mean free path of secondary fragments. Using the same techniques of analysis used for the accelerator ions, evidence is found for anomalously short mean free paths of secondary fragments in the first centimeter after production.

Barber, H. B.↗

NASA NTRS1981

Cosmic-ray abundances of elements with atomic number 26 less than or equal to 40 measured on HEAO 3

Individual elements in the cosmic radiation of even atomic number (Z) in the interval 26-40 have been resolved and their relative abundances measured. The results are inconsistent with a cosmic-ray source whose composition in this charge interval is dominated by r-process nucleosynthesis. The ratios of cosmic-ray source abundances to solar system abundances in this interval follow the same general correlation with first ionization potential as for the lighter elements, although there are deviations in detail.

Binns, W. R.↗

NASA NTRS1981

The elemental and isotopic composition of cosmic rays - Silicon to nickel

The reported observations were made with the aid of the Cosmic Ray Isotope Instrument System (CRISIS) which had been designed to detect and resolve the isotopes of cosmic ray nuclei with atomic numbers equal to or greater than 10. The CRISIS detector was flown on a balloon launched from Aberdeen, South Dakota on 1977 May 20. The period 1977 May 19-22 has been classified by Mason et al. (1979) as one of 'superquiet' solar activity, characterized by the lowest fluxes of low-energy solar particles ever observed. The obtained results are presented in a number of graphs and tables. It was found that the elemental and isotopic abundances of Si are solar-like. Elemental S is underabundant in the cosmic rays by a factor of approximately 3 relative to the solar system, but its isotopic composition resembles the solar composition with S-32 being the dominant isotope. Elemental Ar is virtually absent in the source, and the observed isotopic composition is consistent with a secondary origin. Elemental Ni has a solar-like abundance.

Young, J. S.↗

NASA NTRS1981

The UH-nuclei cosmic ray detector on the third High Energy Astronomy Observatory

The third High Energy Astronomy Observatory satellite (HEAO-3) carries a particle telescope for the detection of highly charged cosmic ray nuclei. These nuclei, which have Z equal to or greater than 28, are much rarer than the lower charged nuclei in the cosmic radiation. As a consequence, this particle telescope was required to have a large collecting area as well as an ability to resolve individual elements. This paper describes the telescope, composed of large area parallel plate ionization chambers, multiwire ion chamber hodoscopes and a Cherenkov radiation detector. The resulting telescope has a total geometry factor of 59,000 sq cm sr and is capable of measuring the charges of nuclei in the range Z = 14-120.

Binns, W. R.↗

NASA NTRS1981

Implications of ultraheavy cosmic-ray source composition derived from observations by the HEAO-3 heavy nuclei experiment

The contribution of r-process and s-process nucleosynthesis to the Cameron (1980) solar system (SS) abundances for Z at least 33 has been derived. In the interval Z equals 34-40 HEAO-3 data extrapolated to the cosmic-ray source (CRS) fit the solar system mix better than r-process. In the interval Z between 26-40 the HEAO-3 results for CRS/SS follow the same general correlation with first ionization potential as for the lighter elements although there are deviations in detail.

Israel, M. H.↗

NASA NTRS1981

Isotopes of cosmic ray elements from neon to nickel

Results obtained from a balloon exposure of a cosmic ray detector flown in 1977 are reported. The charge resolution ranged from 0.19 to 0.21 charge units between neon and nickel and the mass resolution for nuclei stopped in the emulsions ranged from 0.40 to 0.70 amu for A between 20 and 60 amu. This was enough to correctly identify almost all nuclei, but not to uniquely resolve neighboring mass peaks. Both Ne and Mg show evidence for neutron enrichment relative to the solar system abundance. Si and S are consistent with solar abundances, while Ar has no significant source abundances. P, Cl and K have essentially no primary component and the isotopic distribution observed is quite consistent with that expected from propagation. An excess of Ca-44 at the source is shown, indicating high metallicity in the source. The abundance of Fe-58 is nine percent or less, and Ni shows a one-to-one ratio for Ni-58 to 60, implying intermediate metallicity.

Waddington, C. J.↗