We report here an analysis that, for the first time, systematically normalizes the data from the HEAO 3 He~vy Nuclei Experiment on .the cosmic-ray abundances of all the elements heavier than germanium to that of .iron. In the range of atomic number Z, 33 ::;; Z ::;; 60, the analysis yields abundances of odd-even element pa1rs. These abundances are consistent with a cosmic-ray source having a composition similar to that of the solar system, but subject to so~rce. fractionation correlated with the first ionization potential (FIP) of each element. For Z > 60, the analysis yields abundances of element groups. For these heaviest nuclei, we find an enhancement of the abundance of the platinum group, elements with 74::;; Z::;; 80, relative to that in a propagated solar system source, and a corresponding increase in the abundance of the largely secondary elements in the range 62::;; Z ~ ?3. These abundances su~gest that there is an enhancement of the r-process contribution to the sour~ nucl:i m the:: Z > 60 charge region. Over the entire region of charge, standard leaky box models of propagation satisfactorily model secondary production.

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Abstract. The Cosmic Ray Isotope Spectrometer is designed to cover the highest decade of the Advanced Composition Explorer's energy interval, from 50 to 500 MeV/nucleon, with isotopic resolution for elements from Z ' 2 to Z ' 30. The nuclei detected in this energy interval are predominantly cosmic rays originating in our Galaxy. This sample of galactic matter can be used to investigate the nucleosynthesis of the parent material, as well as fractionation, acceleration, and transport processes that these particles undergo in the Galaxy and in the interplanetary medium.Charge and mass identification with CRIS is based on multiple measurements of dE=dx and total energy in stacks of silicon detectors, and trajectory measurements in a scintillating optical fiber trajectory (SOFT) hodoscope. The instrument has a geometrical factor of 250 cm 2 sr for isotope measurements, and should accumulate 5 10 6 stopping heavy nuclei (Z 2) in two years of data collection under solar minimum conditions.

Measurements of the abundances of cosmic-ray 59 Ni and 59 Co are reported from the Cosmic-Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer. These nuclides form a parent-daughter pair in a radioactive decay which can occur only by electron capture. This decay cannot occur once the nuclei are accelerated to high energies and stripped of their electrons. The CRIS data indicate that the decay of 59 Ni to 59 Co has occurred, leading to the conclusion that a time longer than the yr half-life of 59 Ni elapsed before the particles 4 7.6 # 10 were accelerated. Such long delays indicate the acceleration of old, stellar or interstellar material rather than fresh supernova ejecta. For cosmic-ray source material to have the composition of supernova ejecta would require that these ejecta not undergo significant mixing with normal interstellar gas before ∼10 5 yr has elapsed.

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