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Our previous studies showed that the fragmentation cross sections of gold nuclei interacting in hydrogen have large variations between the values measured at 0.9 and 10.6 GeV/n, which has very significant implications on calculations of the propagation of the heaviest UH cosmic ray nuclei, such as Pb and Pt We have now completed a series of runs at the Brookhaven AGS using beams of gold nuclei of intermediate energy. The data from these runs will allow us to establish the excitation functions for these cross sections in a wide range of targets and hence model propagation more accurately than hitherto. In addition we will be able to study the energy dependence of nuclear charge pickup, electromagnetic dissociation and fission. Beams of gold nuclei with seven energies between 4.0 and 0.9 Ge V /n were studied interacting in targets ranging in mass from hydrogen to lead. We will present data on the cross sections derived from several of these beams and discuss some of the implications.

The Advanced Composition Explorer, to be launched in August of 1997, will include six high resolution spectrometers that will measure the composition of interplanetary nuclei with 2≤Z≤28 from < 1 keV/nuc to ~500 MeV/nuc. Three additional instruments will provide the interplanetary context for these measurements. We give a brief introduction to the ACE mission, its instrumentation, and its goals.

A set of particle detectors has been exposed to beams of _(79)Au nuclei at ~ 11 Ge V /nucleon from the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). We report preliminary results on the responses obtained from silicon solid state detectors and from Cerenkov counters utilizing total internal reflection with waveshifter bars for readout.

The Advanced Composition Explorer (ACE) mission is supported by an ACE Science Center for the purposes of facilitating collaborative work. It is intended that coordinated use of a centralized science facility by the ACE team will ensure appropriate use of data formatting standards, thus easing access to the data; will improve communications within and to the ACE science working team; and will reduce redundant effort in data processing.

Measurements of the elemental abundances of galactic cosmic ray nuclei with charge 26≤z≤92 can provide important information that should help to resolve the question of cosmic-ray origin; i.e. whether cosmic rays originate from the acceleration of interstellar grain material or from preferential selection and acceleration of nuclei from stellar photosphere-chromosphere regions with T-10^4 based on first ionization potential. They will also refine tests of whether freshly synthesized rprocess material is a significant component in cosmic rays. The detector concept described utilizes an array of silicon detectors for dF/dx measurements, two Cherenkov counters with radiators of different refractive index for velocity determination (one using aerogel and one using a novel waveshifter readout approach), and scintillating fibers for a hodoscope/time-of-flight detector. The numbers of particles which can be collected with this approach and the expected charge resolution are discussed.

We describe a mission concept which has as its primary objective the measurement of the elemental abundances of galactic and solar energetic nuclei over the charge range of 14 less than or equal to Z less than or equal to 92. The instruments would have sufficient collecting power to improve the number of particles collected over that of previous measurements by more than an order of magnitude and, more important, will have the capability to clearly distinguish individual elements. These measurements are of fundamental importance to an understanding of the origin, nucleosynthesis, and acceleration of energetic galactic and solar particles.

We present a model for composition of heavy ions in the solar energetic particles (SEP). The SEP composition in a typical large solar particle event reflects the composition of the Sun, with adjustments due to fractionation effects which depend on the first ionization potential (FIP) of the ion and on the ratio of ionic charge to mass (Q/M). Flare-to-flare variations in composition are represented by parameters describing these fractionation effects and the distributions of these parameters are presented.

In 1990 we exposed a wide range of targets to beams of relativistic krypton and silver nuclei at the LBL Bevalac at energies from 0.5 to 1.5 GeV/nucleon. Incoming and fragmented nuclei were detected in an array of ion chambers, Cherenkov detectors, and multiwire proportional chambers. The total and partial cross sections for charge-changing interactions have been measured, with emphasis on those of cosmic ray interest. These cross sections are compared to those from parametric fits.

The fragmentation of 10.6 GeV/n Au in CH_2. C, Al, Cu, Sn, and Pb targets has been studied using an array of ion chambers, multi-wire proportional counters (MWPC), and Cherenkov counters. Total charge-changing cross sections were found to be monotonically increasing with target charge over cross sections measured and derived from lower energy data. Partial charge-changing cross sections yielding charge changes less than 1O were depressed from those measured at lower energy.

The relative abundances of various elements in the solar photosphere and the solar corona are re-determined from relative abundances of solar energetic particles (SEP) in the light of revised solar spectroscopic abundances. We find excellent correlation between SEP-based abundances and spectroscopic abundances, after correcting for fractionation due to ionic charge-to-mass ratio and first ionization potential.

A technique for documenting, formatting, and storing data is introduced and briefly described. The documentation standard, now labeled the tennis standard, allows creation of function libraries and utilities to gain access to the data, greatly facilitating input and output; these functions and utilities are described. A comparison of this standard with the better known HDF and CDF standards is made.

We have measured the total charge changing cross sections as a function of energy for projectile _(36)Kr nuclei in a wide range of targets ranging from polyethylene to lead. These cross sections are energy dependent and the dependence increases as the target mass increases.

Composition measurements were made of the energetic particles produced in the series of large flares which began on 19 October 1989, using the Galileo Heavy Ion Counter which is sensitive to nuclei ranging from carbon (Z=6) to nickel (Z=28) over an energy range from about 5 MeV/nucleon to >70 MeV/nucleon. The observations are unique in that clean, statistically well-measured abundances are available for heavy ions for an unusually large flare. For elements with low First Ionization Potential (FIP), these results show the same correlation of relative abundances with the ion charge to mass ratio as the earlier Voyager observations of solar energetic particles 1 . After correction for selection on the basis of this charge to mass ratio, the abundances of all the elements measured show the expected step-function correlation with FIP, when compared to the spectroscopic photspheric abundances.

In order to evaluate the performance of plastic scintillators for the detection of Ultra-Heavy cosmic ray nuclei, as envisaged in paper OG 10.1.14P, we have conducted experiments at the LBL Bevalac in which we exposed NE-114 and acrylic scintillators to beams of 47Ag ions and its interaction fragments. As a result we have calibrated these scintillators over the charge range 31 ≤ Z ≤ 47. Our results show that a combination of Cherenkov and scintillator detectors can resolve individual charges over this charge range. The resolution obtained in scintillator was 0.24 and 0.28 cu for NE-114 and acrylic scintillator respectively. In addition the light emission is shown to be linear to a good approximation with dE/dx over this charge range.

A definitive study of the elemental abundances of nuclei over the charge range of 20 ≤ Z ≤ 100 requires a satellite mission capable of obtaining high statistics and excellent charge resolution over the full charge range. Such a mission, utilizing an electronic instrument which is an evolution of the HEA0-3 Heavy Nuclei Experiment, is described here.

We report updates of recently published results on cosmic ray energy spectra of the sub-iron nuclei. This paper is based on the following analysis and improvements : a) a better analysis of the charge resolution of the instrument, b) availability of more recent charge-changing cross sections necessary to correct the abundances for interactions inside the detector, and c) a recent revision of the results from the French-Danish C2 experiment on HEA0-3 that were included in our analysis.

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.

The Large Isotope Spectrometer for Astromag (LISA) is an experiment designed to measure the isotopic composition and energy spectra of cosmic rays for elements extending from beryllum through zinc. The overall objectives of this investigation are to study the origin and evolution of galactic matter; the acceleration, transport, and time scales of comsic rays in the galaxy; and search for heavy antinuclei in the cosmic radiation. To achieve these objectives the LISA experiment will make the first identifications of individual heavy cosmic ray isotopes in the energy range from about 2.5 to 4 GeV/n where relativistic time dilation effects enhance the abundances of radioactive clocks and where the effects of solar modulation and cross‐section variations are minimized. It will extend high resolution measurements of individual element abundances and their energy spectra to energies of nearly 1 TeV/n, and has the potential for discovering heavy anti‐nuclei which could not have been formed except in extra‐galactic sources.

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 unstable

We have exposed a detector, similar to the one used on the HEAO Heavy Nuclei Experiment {Binns, et al., 1981) to beams of _(26)Fe, _(57)La, _(61)Ho and _(79)Au at the LBL Bevalac. We will report on the deviations from z2 scaling for the signals in the ion chambers and the Cherenkov counters as a function of energy and Z. These deviations are definitely small and imply an error of less than one charge unit in the charge determinations used in the Heavy Nuclei Experiment (Binns, et al., 1989).

We have examined the fragmentation of relativistic lanthanum and gold nuclei incident on targets of polyethylene, carbon, aluminum, and copper. Attention has been concentrated on those fragments whose atomic numbers were only changed by +1 to -3 from those of the incident nuclei. The cross section for the production of fragments with increased charge is about 10% that for fragments that have lost one charge, or about 1% of the total interaction cross section. We find that the velocity distributions of these fragments can be explained by assuming that they also lose significant numbers of neutrons when they pick up or lose charge, without a need to invoke any energy or momentum loss in the interaction, although we cannot exclude small losses. In particular, we cannot confirm the recent report of large energy losses during the charge pickup process. The relative numbers of neutrons lost can be represented by a simple Gaussian model, and, for those fragments with decreased charge, are much larger than the proton losses. These fragments consequently have large proton excesses and will be highly unstable.

Using the relativistic rise of energy loss as a measure of energy, we have determined the energy dependence of the abundances relative to _(26)Fe of the elements _(18)Ar, _(19)K, _(20)Ca, _(21)Sc, _(22)Ti, _(23)V, and _(28)Ni, from 10 to several hundred Ge V /amu. From the energy dependence of the observed Ar/Fe and Ca/Fe ratios we infer primary source ratios for these elements.

The HEAO-3 Heavy Nuclei Experiment has measured abundances of elements from ^(18)Ar to ^(92)U in the cosmic rays. The results of the ultraheavy elements, those with atomic numbers greater than 30, indicate that the sources of cosmic rays contain a mixture of r-process and s-process material similar to that found in the solar system. This result is at variance with previous indications that the sources are greatly enhanced with freshly synthesized r-process material. Apparent discrepancies between our results and the accepted solar-system abundances have led to a re-examination of data on photospheric abundances of Ge and Pb, resulting in suggested reductions in their values.

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.

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 44≤Z≤48 and 62≤Z≤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. Our results are consistent with solar system abundances modified for first ionization potential with possibly some enhancement of tho r to s ratio.

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

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

Total charge-changing cross sections and partial cross-sections for interactions of 200 GeV ^(197)_(79)Au nuclei incident on carbon and polyethylene (CH_2) targets have been measured during a calibration of the HEA0-3 Heavy Nuclei Experiment. From these we infer the total and partial cross-sections for ^(197)_(79)Au incident on hydrogen. The effects of using these cross-sections in one model of cosmic ray propagation are illustrated. Comparisons to predictions using semi-empirical formulae are shown.

As part of a recent calibration at the LBL Bevalac for the Heavy Nuclei Experiment on HEAO-3, we have compared the response of a set of laboratory ionization chambers to beams of _(26)Fe, _(36)Kr, _(54)Xe, _(67)Ho, and _(79)Au nuclei at maximum energies ranging from 1666 MeV/amu for Fe to 1049 MeV /amu for Au. The response of these chambers shows a significant deviation from the expected energy dependence, but only a slight deviation from Z^2 scaling.

The HEAO-3 Heavy Nuclei Experiment (Binns, et al., 1981) is composed of ionization chambers above and below a plastic Cherenkov counter. We have measured 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 of this experiment. We extend the measurements of the Danish French HEAO-3 experiment (Englemann, et al., 19S3) to higher energies, using the relativistic rise of ionization signal as a measure of energy, and determine source abundances for Ar and Ca.

Over the past few years, we have been analyzing the HEAO-3 measurements of the abundances of ultra-heavy cosmic ray nuclei (Z>26) at earth. 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 knowledge of the total and partial interaction cross sections for these heavy nuclei on hydrogen. Until recently, data on such reactions have been scarce, and we have relied on the semiempirical formalism of Silberberg and Tsao to predict the partial cross sections. 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.

The Heavy Nuclei Experiment on (HEAO-3) high energy astronomy observatory 3 uses a combination of ion chambers and a Cerenkov counter. During analysis, each particle is assigned two parameters, Zc and Zi, proportional to the square roots of the Cerenkov and mean ionization signals respectively. Because the ionization signal is double valued, a unique assignment of particle charge, Z, is not possible in general. Previous work was limited to particles of either high rigidity or low energy, for which a unique charge assignment was possible, although those subsets contain less than 50% of the total number of particles observed. The maximum likelihood technique was used to determine abundances for the complete data set from approx. 1.5 to approx. 80 GeV/amu.

This paper reports an observation of the abundances of cosmic-ray lead and platinum-group nuclei using data from the HEAO-3 Heavy Nuclei Experiment (HNE) which consisted of ion chambers mounted on both sides of a plastic Cherenkov counter (Binns et al., 1981). Previously we have reported on a search for actinide nuclei, Z > 88 (Binns, et al. 1982a). Further analysis with more stringent selections, inclusion of additional data, and a calibration at the LBL Bevalac, have allowed us to obtain the abundance ratio of lead and the platinum group of elements for particles that had a cutoff rigidity R_c > 5 GV.

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.

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.

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 ≥ 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% confidence level, is placed in the ratio of nuclei with Z ≥ 88/(74 ≤ Z ≤87) of 0.03.

A combination of ion chambers and Cerenkov radiators similar to the Heavy Nuclei Experiment flown on HEAO-3 was calibrated at the Bevalac heavy-ion accelerator using beams of Mn-25 nuclei at kinetic energies up to about 1700 MeV/nucleon and Au-79 nuclei up to about 1000 MeV/nucleon. The data show only a small deviation (about 2-3 charge units at Au) from the Z^2 scaling used previously (Binns et al., 1981, 1982, 1983) to analyze the HNE data. Although at lower energy, the calibration indicates that the published relative abundances of the _(50)Sn/_(56)Ba group and the published upper-limit actinide abundances are not likely to be significantly affected by non-Z^2 effects.

The cosmic-ray-source abundances inferred from HEAO-3 observation by the Heavy Nuclei Experiment for 30 < Z < 60 generally follow the correlation with first-ionization potential which has previously been observed for Z < 30. However the low Ge abundance suggests that the elemental "volatility" may be an organizing factor.

The relative abundances of elements in the charge ranges of 75 ≤ Z ≤ 79 (platinum) and 80 ≤ Z ≤ 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 62 ≤ Z ≤ 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.

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 44 < Z < 48 and 62 < Z < 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.

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.

We have examined relativistic nuclei of iron, krypton, xenon, holmium and gold, accelerated to maximum rigidity at the LBL Bevalac, interacting with targets of aluminum, carbon and polyethylene. For each projc*:tile and target combination we determined the total and partial charge changing cross-sections. From these measurements we have developed a new representation of the dependence of the total charge changing cross-sections on beam and target charge. We have also identified simple representations of the variation of the partial cross-sections with the charge of the produced fragments and shown that they are dependent on the charge and energy of the beam.

We shall report results from a calibration of a set of high-resolution ionization chambers and Cherenkov counters at the Lawrence Berkeley Laboratory Bevalac, in November 1986. We obtained exposures to beams of 26Fe, 57La, 67Ho, and 79Au, at several diffyfent energies, ranging from -300 MeV/amu to a maximum between 1 and 1.6 Ge V lamu. The detectors were basically similar to those used in the HEA0-3 HNE (Binns et al. 1981) and these exposures were intended to calibrate the response of the HNE detectors to UH nuclei in the cosmic radiation. For nuclei of low .atomic number (Z), the response of these detectors scales like Z2; however, at high Z this scaling is expected to break down (Ahlen 1980,1982; Derrickson et til. 1981).

Measurements from the Heavy Nuclei Experiment (Binns et al. 1981a) aboard the HEAO-3 satellite have been used to extract definite-abundance values for the even charge nuclei and upper limit values for the less abundant odd charge nuclei. Individual peaks in the charge spectrum for even charge nuclei over this charge region are observed and the cosmic ray abundances obtained from this charge spectrum are compared with abundances characteristic of the solar system and with a solar system r process.

Analysis of a new, higher resolution data set from the Heavy Nuclei Experiment on the HEA0-3 spacecraft has yielded the cosmic ray abundances relative to iron of oddeven element pairs with atomic number, Z, in the range 33≤Z≤60. The abundances are consistent with a solar-system source provided an allowance is made for a source fraetionation based on first ionization potential (FIP). However, extending this analysis· to element groups with Z>60, we find enhancements of the Pt group (74≤Z≤80) abundance relative to the solar system and a corresponding increase in the largely secondary nuclei in the range 62≤Z≤73, in agreement with recent Ariel-6 results. These abundances suggest an enhancement of the r-process contribution to the source of the Z > 60 nuclei.

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.

We have examined the fragmentation of relativistic lanthanum and gold nuclei incident on targets of polyethylene, carbon, aluminum, and copper. Attention has been concentrated on those fragments whose atomic numbers were only changed by +1 to -3 from those of the incident nuclei. The cross section for the production of fragments with increased charge is about 10% that for fragments that have lost one charge, or about 1% of the total interaction cross section. We find that the velocity distributions of these fragments can be explained by assuming that they also lose significant numbers of neutrons when they pick up or lose charge, without a need to invoke any energy or momentum loss in the interaction, although we cannot exclude small losses. In particular, we cannot confirm the recent report of large energy losses during the charge pickup process. The relative numbers of neutrons lost can be represented by a simple Gaussian model, and, for those fragments with decreased charge, are much larger than the proton losses. These fragments consequently have large proton excesses and will be highly unstable.

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.

The radial intensity-gradient of cosmic-ray protons has been calculated for a range of values of the distance to the boundary of a spherically symmetric solar-modulation region. We find that the radial dependence of the gradients may be described in terms of two characteristic domains of the modulation region: (a) an "inner region" where the gradients are relatively small and constant, and (b), an "outer region"' where the gradients are large and show a strong radial dependence. The magnitude of the gradient in the inner region is small for reasonable values for the physical parameters of the modulation mechanism.