Energy spectra of elements with 18 or = Z or = 28 between 10 and 300 GeV/amu

The HEAO-3 Heavy Nuclei Experiment is composed of ionization chambers above and below a plastic Cerenkov counter. The energy dependence of the abundances of elements with atomic number, Z, between 18 and 28 at very high energies where they are rare and thus need the large area x time are measured. The measurements of the Danish-French HEAO-3 experiment (Englemann,, et al., 1983) are extended to higher energies, using the relativistic rise of ionization signal as a measure of energy. Source abundances for Ar and Ca were determined

Interactions of heavy nuclei, Kr, Xe and Ho, in light targets

Over the past few years, the HEAO-3 measurements of the abundances of ultra-heavy cosmic ray nuclei (Z 26) at earth have been analyzed. In order to interpret these abundances in terms of a source composition, allowance must be made for the propagation of the nuclei in the interstellar medium. Vital to any calculation of the propagation is a knowlege of the total and partial interaction cross sections for these heavy nuclei on hydrogen. Until recently, data on such reactions have been scarce. However, now that relativistic heavy ion beams are available at the LBL Bevalac, some of the cross sections of interest can be measured at energies close to those of the cosmic ray nuclei being observed. During a recent calibration at the Bevalac of an array similar to the HEAO-C3 UH-nuclei detector, targets of raphite (C), polyethylene (CH2), and aluminum were exposed to five heavy ion beams ranging in charge (Z) from 36 to 92. Total and partial charge changing cross sections for the various beam nuclei on hydrogen can be determined from the measured cross sections on C and CH2, and will be applied to the propagation problem. The cross sections on Al can be used to correct the abundances of UH cosmic rays observed in the HEAO C-3 detector for interactions in the detector itself

The Abundances of the Heavier Elements in the Cosmic Radiation

We review current work on the abundances of the ultraheavy elements in the cosmic radiation, those with Z≳30. Those abundances are compared with predictions based on propagation and fractionation of elemental abundances from various assumed sources of the cosmic rays. We find striking similarities between the solar system and the cosmic ray source abundances for those elements with 32≤Z≤60. For elements with Z≳60, there appears to be a substantial enhancement in the abundances of elements synthesized in the r‐process

Cosmic Ray Elemental Abundances for 26<Z<40 Measured on HEAO-3

Abundances relative to _(96)Fe have been derived for elements with charge, 2, in the range 32≤z≤40. With a resolution better than 0.5 charge unit at Z=38, we resolve _(37)Rb from _(38)Sr and use the Rb/Sr ratio to place a limit on the r-proccss enhancement of the cosmic ray source material in this charge range

Implications of Source Abundances of Ultraheavy Cosmic Rays

The ratio of cosmic ray source abundance to solar-system abundance was examined for individual elements. Correlations of these ratios with first-ionization potential (FIP) and the expected mass-to-charge ratio (A/Q) of the elements in a million-degree plasma are analyzed. The FIP correlation was examined and it is shown that the correlation is affected by the choice of C2 or C1 chondritic meteorites as the solar-system standard for comparison. An A/Q correlation is suggested as a consequence of the shock acceleration model in the hot interstellar medium. The correlations are presented

Implications of Ultraheavy Cosmic-Ray Source Composition Derived from Observations by the HEAO-3 Heavy Nuclei Experiment

We have derived the contribution of r-process and s-process nucleosynthesis to the Cameron (1980) solar system (SS) abundances for Z~33. In the interval 34 ~Zs; 40 our HEA0-3 data extrapolated to the cosmic-ray source (CRS) fit the solar system mix better than r-process. In the interval 26 < Z < 40 the HEA0-3 results for CRS/SS follow the same general correlation with first ionization potential as for the lighter eiements although there are deviations in detail

Global Representation of the Cross Sections for the Production of Fragments of UH Nuclei

We have examined the fragmentation of relativistic iron, lanthanum, holmium and gold nuclei with energies between 500 and 1200 MeV/n incident on targets of polyethylene, carbon, aluminum, copper and lead. We have determined 1,256 elemental partial cross sections for the production of fragments from interactions in pure target materials. Deduced values have been found for another 417 cross sections in a hydrogen medium. The dependencies of these cross sections on energy, mass and charge have been studied. We have generated a seven parameter global fit to the cross sections for the heavy targets which fits a significant range of the data with a standard deviation of 7%. We have also generated a similar global fit to the cross sections for the hydrogen target which fits a slightly smaller range of the data with a standard deviation of 10%. These representations show that weak factorization can apply, but slightly better fits can be obtained without it. The mean mass losses observed for fragments that have lost a few protons, show that typically three or more neutrons are lost with each proton, producing fragment nuclei that must be highly proton rich, and consequently very unstabl

Heavy Nuclei Experiment on HEAO-3

The third High Energy Astronomical Observatory, HEAO-3 was launched on the 20th Sept., 1979 into a 496 km, 43.6° orbit, and has since been successfully returning data from all three experiments on board. One of these experiments, that intended to study the heavy and ultra heavy nuclei in the cosmic radiation, is described here

Cosmic Ray Abundances of Sn, Te, Xe, and Ba Nuclei Measured on HEAO 3

Elements with even atomic number ( Z) in the interval 50 ~ Z ~ 56 have been resolved in the cosmic radiation using the Heavy Nuclei Experiment on the HEAO 3 satellite. The observation that 50Sn and 56Ba are more abundant than 52Te Elements with even atomic number ( Z) in the interval 50 ~ Z ~ 56 have been resolved in the cosmic radiation using the Heavy Nuclei Experiment on the HEAO 3 satellite. The observation that 50Sn and 56Ba are more abundant than 52Te and 54Xe is inconsistent with a purer-process cosmic-ray source. Adjustment of source abundances for an enhancement of those elements with a low first ionization potential does not change this conclusion and 54Xe is inconsistent with a purer-process cosmic-ray source. Adjustment of source abundances for an enhancement of those elements with a low first ionization potential does not change this conclusion

Abundances of Cosmic Ray Nuclei for 26 ≤ Z ≤ 40 From HEAO-3 Heavy Nuclei Experiment

Individual elements in the cosmic radiation of even atomic number (Z)in the interval 26≤ Z ≤ 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