Relative abundances of elements (20 or = Z or = 28) at energies up to 70 GeV/amu using relativistic rise in ion chambers

The results of a new balloon borne cosmic ray detector flown from Palestine, TX in Sept., 1982 are discussed. The exposure of 62 square meter-ster-hr is sufficient to prove the concept of using gas ionization chambers as energy measuring devices in the relativistic rise region. The abundances, relative Fe-26, of the pure secondaries Cr-22 and Ti-24, the pure primary Ni26, and the mixed primary and secondary Ca-20 between 6 and 70GeV/amu were measured

Bevalac calibration of the SOFIE range and hodoscope detectors

The scintillating optical fiber isotope experiment (SOFIE) is a Cerenkov-dE/dx-Range experiment which was developed initially for balloon flight to study the isotopic composition of cosmic rays in the iron region. The electronic range and hodoscope detectors use scintillating optical fibers to image the tracks of stopping charged particles and to determine their trajectory. The particle range is determined and used together with a Cerenkov measurement to determine the mass of the stopping particle. Preliminary results of a Bevalac calibration performed in August, 1984 with a prototype of the balloon flight instrument, to study the measurement precision in range and trajectory which could be attained with this detector are described

Observation of VH and VVH cosmic rays with an ionization-Cerenkov detector system

Heavy and ultraheavy nuclei observations of cosmic rays using ionization chamber-Cerenkov counter syste

Scintillator-fiber charged particle track-imaging detector

A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented

Large area pulse ionization chamber for measurement of extremely heavy cosmic rays

Parallel plate ionization chamber for identifying relativistic cosmic ray nucle

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

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

Anisotropy of Galactic Iron of Energy 30 to 500 GeV/amu Studied by HEAO-3

The anisotropy of cosmic ray iron observed by the Heavy Nuclei Experiment [1] on the HEA0-3 spacecraft has been studied. A high rigidity data set was chosen by requiring the Stoermer cutoff be greater than 7 GV, and the energy of individual events was determined by relativistic rise in the ion chamber signal [2]. Events which have estimated rigidity well above their Stoermer cutoff rigidity were chosen in order to reduce the effect of the geomagnetic field on the cosmic ray trajectories. Selecting events with estimated rigidity greater than ~58 GV from eight months of data yields 2459 events. This data set allows an anisotropy measurement with a statistical uncertainty of 3%. We will continue to try increasing the size. of the selected data set while limiting systematic errors due to the geomagnetic and interplanetary fields

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