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M E Wiedenbeck - One of the best experts on this subject based on the ideXlab platform.

  • 3he rich solar energetic particles from sunspot jets
    The Astrophysical Journal, 2018
    Co-Authors: Radoslav Bucik, G. M. Mason, R Gomezherrero, M E Wiedenbeck, N Nitta, Linghua Wang
    Abstract:

    Solar sources of suprathermal ( 10 MeV/nucleon) 3He-rich SEPs remain unexplored. Here we present two of the most intense 3He-rich (3He/4He>1) SEP events of the current solar cycle 24 measured on the Advanced Composition Explorer at energy >10 MeV/nucleon. Although 3He shows high intensities, Z>2 ions are below the detection threshold. The events are accompanied by type-III radio bursts, but no type-II emission as typically seen for suprathermal 3He-rich SEPs. The corresponding solar sources were analyzed using high-resolution, extreme-ultraviolet imaging and photospheric magnetic field observations on the Solar Dynamics Observatory. We find the sources of these events associated with jets originating at the boundary of large sunspots with complex beta-gamma-delta magnetic configuration. Thus, details of the underlying photospheric field apparently are important to produce 3He to high energies in the examined events.

  • association of 3he rich solar energetic particles with large scale coronal waves
    The Astrophysical Journal, 2016
    Co-Authors: Radoslav Bucik, G. M. Mason, D E Innes, M E Wiedenbeck
    Abstract:

    Small 3He-rich solar energetic particle (SEP) events have been commonly associated with extreme-ultraviolet (EUV) jets and narrow coronal mass ejections (CMEs) which are believed to be the signatures of magnetic reconnection involving field lines open to interplanetary space. The elemental and isotopic fractionation in these events are thought to be caused by processes confined to the flare sites. In this study we identify 32 3He-rich SEP events observed by the Advanced Composition Explorer near the Earth during the solar minimum period 2007-2010 and examine their solar sources with the high resolution Solar Terrestrial Relations Observatory (STEREO) EUV images. Leading the Earth, STEREO-A provided for the first time a direct view on 3He-rich flares, which are generally located on the Sun's western hemisphere. Surprisingly, we find that about half of the 3He-rich SEP events in this survey are associated with large-scale EUV coronal waves. An examination of the wave front propagation, the source-flare distribution and the coronal magnetic field connections suggests that the EUV waves may affect the injection of 3He-rich SEPs into interplanetary space.

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Com- position Measurements
    2016
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, E R Christian, M E Wiedenbeck
    Abstract:

    Abstract: The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly 22Ne/20Ne and 31Ga/32Ge show that the Composition is consistent with source material that is a mix of ∼80 % interstellar medium material (with Solar System abundances) and 20 % outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an ∼80%–20 % mix rather than pure interstellar medium material. We conclude that these data are consistent with an OB association origin of galactic cosmic rays

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE The Solar-cycle Variation of 3He from Solar Energetic Particle Events
    2016
    Co-Authors: M E Wiedenbeck, G. M. Mason
    Abstract:

    Abstract: A study of the frequency of occurrence of enhancements of energetic 3He from impulsive solar energetic particle events has been carried out using data from the ULEIS and SIS instruments on the Advanced Composition Explorer spacecraft. The data set, which currently extends over a 15+ year period from late 1997 through early 2013, shows rapid increases in the fraction of time that 3He was observable during both solar cycle 23 and cycle 24. Averaged over the first three years of cycle 24 the fraction of time with 3He detected was significantly less than for a comparable period in cycle 23. Over the period of this study, the variation of 3He exhibited a better correlation with sunspot number than with several other parameters that were investigated

  • Elemental and Isotopic Fractionation in ^He-rich Solar Energetic Particle Events
    2015
    Co-Authors: M E Wiedenbeck, T T Von Rosenvinge
    Abstract:

    Abstract. Using data from the Solar Isotope Spectrometer (SIS) on the Advanced Composition Explorer (ACE) mission, heavy ion Composition measurements have been made in 26 He-rich solar energetic particle (SEP) events that occurred between 1998 and 2004. Relative abundances of 13 elements from C through Ni have been investigated, as have the isotopic Compositions of the elements Ne and Mg. We find a general tendency for the abundances to follow trends similar to those found in gradual SEP events, in which fractionation can be represented in the form of a power-law in Q/M. However several deviations from this pattern are noted that may provide usefid diagnostics of the acceleration process occurring in solar flares

M H Israel - One of the best experts on this subject based on the ideXlab platform.

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Elemental GCR Observations During the 2009–2010 Solar Minimum Period
    2016
    Co-Authors: K A Lave, W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, A. J. Davis, E R Christian, E C Stone
    Abstract:

    Abstract: Using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we present new measurements of the galactic cosmic ray (GCR) elemental Composition and energy spectra for the species B through Ni in the energy range ∼50–550 MeV/nucleon during the record setting 2009–2010 solar minimum period. These data are compared with our observations from the 1997–1998 solar minimum period, when solar modulation in the heliosphere was somewhat higher. For these species, we find that the intensities during the 2009–2010 solar minimum were ∼20 % higher than those in the previous solar minimum, and in fact were the highest GCR intensities recorded during the space age. Relative abundances for these species during the two solar minimum periods differed by small but statistically significant amounts, which are attributed to the combination of spectral shape differences between primary and secondary GCRs in the interstellar medium and differences between the levels of solar modulation in the two solar minima. We also present the secondary-to-primary ratios B/C and (Sc+Ti+V)/Fe for both solar minimum periods, and demonstrate that these ratios are reasonably well fit by a simple “leaky-box ” galactic transport model that is combined with a spherically symmetric solar modulation model

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Com- position Measurements
    2016
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, E R Christian, M E Wiedenbeck
    Abstract:

    Abstract: The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly 22Ne/20Ne and 31Ga/32Ge show that the Composition is consistent with source material that is a mix of ∼80 % interstellar medium material (with Solar System abundances) and 20 % outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an ∼80%–20 % mix rather than pure interstellar medium material. We conclude that these data are consistent with an OB association origin of galactic cosmic rays

  • elemental Composition and energy spectra of galactic cosmic rays during solar cycle 23
    The Astrophysical Journal, 2009
    Co-Authors: W R Binns, A C Cummings, G A De Nolfo, M E Wiedenbeck, J S George, A. J. Davis, P L Hink, K A Lave, M H Israel
    Abstract:

    We report improved measurements of elemental abundances and spectra for galactic cosmic-ray (GCR) nuclei obtained by the Cosmic Ray Isotope Spectrometer on board NASA's Advanced Composition Explorer (ACE) spacecraft during the minimum and maximum phases of solar cycle 23. We discuss results for particles with nuclear charge 5 ≤ Z ≤ 28 and typical energies between 50 and 500 MeV nucleon^(–1). We demonstrate that a detailed "leaky box" Galactic propagation model combined with a spherically symmetric solar modulation model gives a good (but not perfect) fit to the observed spectra by using a solar modulation parameter of φ = 325 MV at solar minimum and φ = 900 MV at solar maximum. Although our results are generally consistent with previous measurements from space-based and balloon-based missions, there are significant differences. The large geometrical acceptance and excellent charge resolution of the instrument result in the most detailed and statistically significant record of GCR Composition to date in this energy range. The measurements reported here serve as a high-precision baseline for continued studies of GCR Composition, solar modulation over the solar cycle, space radiation hazards, and other applications.

  • abundance measurements of zn ga ge se from the cosmic ray isotope spectrometer cris experiment on the Advanced Composition Explorer ace satellite
    Bulletin of the American Physical Society, 2009
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, M E Wiedenbeck
    Abstract:

    The cosmic ray elemental abundances of _(30)Zn, _(31)Ga, _(32)Ge, and _(34)Se provide important tests of the model of the OB-association origin of galactic cosmic rays that has resulted from previous ACE measurements of the neon and iron isotopes and which appears to be confirmed by elemental abundances of Zn, Ga, Ge, and Se measured by the balloon-borne Trans-Iron Galactic Element Recorder (TIGER). These ultra-heavy (Z≥30) nuclei are very rare and require an instrument with a large product of geometrical factor and exposure time. We have measured these abundances using the CRIS instrument, which has a geometrical factor of about 250 cm^2sr, on the NASA-ACE spacecraft. Over the 11+ years since launch in 1997 we have collected ∼400 nuclei with Z≥30 over the energy range of ∼150 to 600 MeV/nucleon. These measured abundances relative to iron are presented and compared with those from the TIGER and HEAO-3 experiments. Our measurements are in reasonable agreement with the TIGER results and are consistent with an OB association origin of galactic cosmic rays.

  • cosmic ray neon wolf rayet stars and the superbubble origin of galactic cosmic rays
    arXiv: Astrophysics, 2005
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, M E Wiedenbeck, Marcel Arnould, J S George, Stephane Goriely, Georges Meynet
    Abstract:

    The abundances of neon isotopes in the galactic cosmic rays (GCRs) are reported using data from the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE). We compare our ACE-CRIS data for neon and refractory isotope ratios, and data from other experiments, with recent results from two-component Wolf-Rayet (WR) models. The three largest deviations of GCR isotope ratios from solar-system ratios predicted by these models are indeed present in the GCRs. Since WR stars are evolutionary products of OB stars, and most OB stars exist in OB associations that form superbubbles, the good agreement of these data with WR models suggests that superbubbles are the likely source of at least a substantial fraction of GCRs.

G. M. Mason - One of the best experts on this subject based on the ideXlab platform.

  • 3he rich solar energetic particles from sunspot jets
    The Astrophysical Journal, 2018
    Co-Authors: Radoslav Bucik, G. M. Mason, R Gomezherrero, M E Wiedenbeck, N Nitta, Linghua Wang
    Abstract:

    Solar sources of suprathermal ( 10 MeV/nucleon) 3He-rich SEPs remain unexplored. Here we present two of the most intense 3He-rich (3He/4He>1) SEP events of the current solar cycle 24 measured on the Advanced Composition Explorer at energy >10 MeV/nucleon. Although 3He shows high intensities, Z>2 ions are below the detection threshold. The events are accompanied by type-III radio bursts, but no type-II emission as typically seen for suprathermal 3He-rich SEPs. The corresponding solar sources were analyzed using high-resolution, extreme-ultraviolet imaging and photospheric magnetic field observations on the Solar Dynamics Observatory. We find the sources of these events associated with jets originating at the boundary of large sunspots with complex beta-gamma-delta magnetic configuration. Thus, details of the underlying photospheric field apparently are important to produce 3He to high energies in the examined events.

  • association of 3he rich solar energetic particles with large scale coronal waves
    The Astrophysical Journal, 2016
    Co-Authors: Radoslav Bucik, G. M. Mason, D E Innes, M E Wiedenbeck
    Abstract:

    Small 3He-rich solar energetic particle (SEP) events have been commonly associated with extreme-ultraviolet (EUV) jets and narrow coronal mass ejections (CMEs) which are believed to be the signatures of magnetic reconnection involving field lines open to interplanetary space. The elemental and isotopic fractionation in these events are thought to be caused by processes confined to the flare sites. In this study we identify 32 3He-rich SEP events observed by the Advanced Composition Explorer near the Earth during the solar minimum period 2007-2010 and examine their solar sources with the high resolution Solar Terrestrial Relations Observatory (STEREO) EUV images. Leading the Earth, STEREO-A provided for the first time a direct view on 3He-rich flares, which are generally located on the Sun's western hemisphere. Surprisingly, we find that about half of the 3He-rich SEP events in this survey are associated with large-scale EUV coronal waves. An examination of the wave front propagation, the source-flare distribution and the coronal magnetic field connections suggests that the EUV waves may affect the injection of 3He-rich SEPs into interplanetary space.

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE The Solar-cycle Variation of 3He from Solar Energetic Particle Events
    2016
    Co-Authors: M E Wiedenbeck, G. M. Mason
    Abstract:

    Abstract: A study of the frequency of occurrence of enhancements of energetic 3He from impulsive solar energetic particle events has been carried out using data from the ULEIS and SIS instruments on the Advanced Composition Explorer spacecraft. The data set, which currently extends over a 15+ year period from late 1997 through early 2013, shows rapid increases in the fraction of time that 3He was observable during both solar cycle 23 and cycle 24. Averaged over the first three years of cycle 24 the fraction of time with 3He detected was significantly less than for a comparable period in cycle 23. Over the period of this study, the variation of 3He exhibited a better correlation with sunspot number than with several other parameters that were investigated

  • multi spacecraft observations of recurrent 3he rich solar energetic particles
    The Astrophysical Journal, 2014
    Co-Authors: Radoslav Bucik, G. M. Mason, D E Innes, Andreas Korth, Urs Mall, R Gomezherrero
    Abstract:

    We study the origin of {sup 3}He-rich solar energetic particles (<1 MeV nucleon{sup –1}) that are observed consecutively on STEREO-B, Advanced Composition Explorer (ACE), and STEREO-A spacecraft when they are separated in heliolongitude by more than 90°. The {sup 3}He-rich period on STEREO-B and STEREO-A commences on 2011 July 1 and 2011 July 16, respectively. The ACE {sup 3}He-rich period consists of two sub-events starting on 2011 July 7 and 2011 July 9. We associate the STEREO-B July 1 and ACE July 7 {sup 3}He-rich events with the same sizeable active region (AR) producing X-ray flares accompanied by prompt electron events, when it was near the west solar limb as seen from the respective spacecraft. The ACE July 9 and STEREO-A July 16 events were dispersionless with enormous {sup 3}He enrichment, lacking solar energetic electrons and occurring in corotating interaction regions. We associate these events with a small, recently emerged AR near the border of a low-latitude coronal hole that produced numerous jet-like emissions temporally correlated with type III radio bursts. For the first time we present observations of (1) solar regions with long-lasting conditions for {sup 3}He acceleration and (2) solar energetic {sup 3}He that is temporarily confined/re-accelerated inmore » interplanetary space.« less

  • evidence for mass per charge dependent acceleration of a multiple component seed population by cme driven interplanetary shocks near 1 au
    The Astrophysical Journal, 2008
    Co-Authors: F Allegrini, G. M. Mason, H Kucharek, M I Desai, E Mobius
    Abstract:

    Using measurements from the ULEIS and SEPICA instruments on board the Advanced Composition Explorer between 1997 November and 2000 October, we have surveyed the abundances of 0.25-0.8 MeV nucleon−1 He+,3He, and heavy ions from C-Fe during 18 CME-driven interplanetary (IP) shocks observed near 1 AU. Our results show that each of the 18 IP shocks is accompanied by enhancements in the intensities of both 3He and He+ ions. In addition we find that, on a case-by-case basis, the abundances of He+ and the heavier elements such as C-Fe (but not 3He) are depleted systematically as a function of the ion's M/Q ratio when compared with those measured in the ambient suprathermal ion population upstream of the IP shocks. These results show for the first time that individual IP shocks routinely accelerate ions from multiple seed populations, such as multiple solar energetic particle events, corotating interaction regions, pickup ions, etc., via systematic rigidity-dependent acceleration processes where ions with higher rigidity or M/Q ratios are accelerated less efficiently than those with lower M/Q ratios. We also compare the M/Q-dependent depletion of these abundances with the locally measured shock parameters and explore why the 3He abundance does not fit into the systematic M/Q-charge-dependent fractionation processes.

A C Cummings - One of the best experts on this subject based on the ideXlab platform.

  • Implications for Cosmic Ray Propagation from ACE Measurements of Radioactive Clock Isotope Abundances
    2020
    Co-Authors: N E Yanasak, W R Binns, A C Cummings, R A Leske, J S George, E R Christian, P L Hink, J Klarmann, M Lijowski, R A Mewaldt
    Abstract:

    Abstract Galactic cosmic rays (GCR) interact to produce secondary fragments as they pass through the interstellar medium (ISM). Abundances of the long-lived radioactive secondaries 10 Be, 26 Al, 36 Cl, and 54 Mn can be used to a derive the confinement time of cosmic rays in the galaxy. Abundances for these species have been measured recently using the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) spacecraft. To interpret this data we have modeled the production and propagation of the radioactive secondaries, taking into account recently published isotopic production cross-sections. Abundances for all species are consistent with a confinement time of esc 2210 6 years

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Elemental GCR Observations During the 2009–2010 Solar Minimum Period
    2016
    Co-Authors: K A Lave, W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, A. J. Davis, E R Christian, E C Stone
    Abstract:

    Abstract: Using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we present new measurements of the galactic cosmic ray (GCR) elemental Composition and energy spectra for the species B through Ni in the energy range ∼50–550 MeV/nucleon during the record setting 2009–2010 solar minimum period. These data are compared with our observations from the 1997–1998 solar minimum period, when solar modulation in the heliosphere was somewhat higher. For these species, we find that the intensities during the 2009–2010 solar minimum were ∼20 % higher than those in the previous solar minimum, and in fact were the highest GCR intensities recorded during the space age. Relative abundances for these species during the two solar minimum periods differed by small but statistically significant amounts, which are attributed to the combination of spectral shape differences between primary and secondary GCRs in the interstellar medium and differences between the levels of solar modulation in the two solar minima. We also present the secondary-to-primary ratios B/C and (Sc+Ti+V)/Fe for both solar minimum periods, and demonstrate that these ratios are reasonably well fit by a simple “leaky-box ” galactic transport model that is combined with a spherically symmetric solar modulation model

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Com- position Measurements
    2016
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, E R Christian, M E Wiedenbeck
    Abstract:

    Abstract: The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly 22Ne/20Ne and 31Ga/32Ge show that the Composition is consistent with source material that is a mix of ∼80 % interstellar medium material (with Solar System abundances) and 20 % outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an ∼80%–20 % mix rather than pure interstellar medium material. We conclude that these data are consistent with an OB association origin of galactic cosmic rays

  • elemental Composition and energy spectra of galactic cosmic rays during solar cycle 23
    The Astrophysical Journal, 2009
    Co-Authors: W R Binns, A C Cummings, G A De Nolfo, M E Wiedenbeck, J S George, A. J. Davis, P L Hink, K A Lave, M H Israel
    Abstract:

    We report improved measurements of elemental abundances and spectra for galactic cosmic-ray (GCR) nuclei obtained by the Cosmic Ray Isotope Spectrometer on board NASA's Advanced Composition Explorer (ACE) spacecraft during the minimum and maximum phases of solar cycle 23. We discuss results for particles with nuclear charge 5 ≤ Z ≤ 28 and typical energies between 50 and 500 MeV nucleon^(–1). We demonstrate that a detailed "leaky box" Galactic propagation model combined with a spherically symmetric solar modulation model gives a good (but not perfect) fit to the observed spectra by using a solar modulation parameter of φ = 325 MV at solar minimum and φ = 900 MV at solar maximum. Although our results are generally consistent with previous measurements from space-based and balloon-based missions, there are significant differences. The large geometrical acceptance and excellent charge resolution of the instrument result in the most detailed and statistically significant record of GCR Composition to date in this energy range. The measurements reported here serve as a high-precision baseline for continued studies of GCR Composition, solar modulation over the solar cycle, space radiation hazards, and other applications.

  • abundance measurements of zn ga ge se from the cosmic ray isotope spectrometer cris experiment on the Advanced Composition Explorer ace satellite
    Bulletin of the American Physical Society, 2009
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, M E Wiedenbeck
    Abstract:

    The cosmic ray elemental abundances of _(30)Zn, _(31)Ga, _(32)Ge, and _(34)Se provide important tests of the model of the OB-association origin of galactic cosmic rays that has resulted from previous ACE measurements of the neon and iron isotopes and which appears to be confirmed by elemental abundances of Zn, Ga, Ge, and Se measured by the balloon-borne Trans-Iron Galactic Element Recorder (TIGER). These ultra-heavy (Z≥30) nuclei are very rare and require an instrument with a large product of geometrical factor and exposure time. We have measured these abundances using the CRIS instrument, which has a geometrical factor of about 250 cm^2sr, on the NASA-ACE spacecraft. Over the 11+ years since launch in 1997 we have collected ∼400 nuclei with Z≥30 over the energy range of ∼150 to 600 MeV/nucleon. These measured abundances relative to iron are presented and compared with those from the TIGER and HEAO-3 experiments. Our measurements are in reasonable agreement with the TIGER results and are consistent with an OB association origin of galactic cosmic rays.

W R Binns - One of the best experts on this subject based on the ideXlab platform.

  • Implications for Cosmic Ray Propagation from ACE Measurements of Radioactive Clock Isotope Abundances
    2020
    Co-Authors: N E Yanasak, W R Binns, A C Cummings, R A Leske, J S George, E R Christian, P L Hink, J Klarmann, M Lijowski, R A Mewaldt
    Abstract:

    Abstract Galactic cosmic rays (GCR) interact to produce secondary fragments as they pass through the interstellar medium (ISM). Abundances of the long-lived radioactive secondaries 10 Be, 26 Al, 36 Cl, and 54 Mn can be used to a derive the confinement time of cosmic rays in the galaxy. Abundances for these species have been measured recently using the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) spacecraft. To interpret this data we have modeled the production and propagation of the radioactive secondaries, taking into account recently published isotopic production cross-sections. Abundances for all species are consistent with a confinement time of esc 2210 6 years

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Elemental GCR Observations During the 2009–2010 Solar Minimum Period
    2016
    Co-Authors: K A Lave, W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, A. J. Davis, E R Christian, E C Stone
    Abstract:

    Abstract: Using observations from the Cosmic Ray Isotope Spectrometer (CRIS) onboard the Advanced Composition Explorer (ACE), we present new measurements of the galactic cosmic ray (GCR) elemental Composition and energy spectra for the species B through Ni in the energy range ∼50–550 MeV/nucleon during the record setting 2009–2010 solar minimum period. These data are compared with our observations from the 1997–1998 solar minimum period, when solar modulation in the heliosphere was somewhat higher. For these species, we find that the intensities during the 2009–2010 solar minimum were ∼20 % higher than those in the previous solar minimum, and in fact were the highest GCR intensities recorded during the space age. Relative abundances for these species during the two solar minimum periods differed by small but statistically significant amounts, which are attributed to the combination of spectral shape differences between primary and secondary GCRs in the interstellar medium and differences between the levels of solar modulation in the two solar minima. We also present the secondary-to-primary ratios B/C and (Sc+Ti+V)/Fe for both solar minimum periods, and demonstrate that these ratios are reasonably well fit by a simple “leaky-box ” galactic transport model that is combined with a spherically symmetric solar modulation model

  • 33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Com- position Measurements
    2016
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, E R Christian, M E Wiedenbeck
    Abstract:

    Abstract: The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly 22Ne/20Ne and 31Ga/32Ge show that the Composition is consistent with source material that is a mix of ∼80 % interstellar medium material (with Solar System abundances) and 20 % outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an ∼80%–20 % mix rather than pure interstellar medium material. We conclude that these data are consistent with an OB association origin of galactic cosmic rays

  • elemental Composition and energy spectra of galactic cosmic rays during solar cycle 23
    The Astrophysical Journal, 2009
    Co-Authors: W R Binns, A C Cummings, G A De Nolfo, M E Wiedenbeck, J S George, A. J. Davis, P L Hink, K A Lave, M H Israel
    Abstract:

    We report improved measurements of elemental abundances and spectra for galactic cosmic-ray (GCR) nuclei obtained by the Cosmic Ray Isotope Spectrometer on board NASA's Advanced Composition Explorer (ACE) spacecraft during the minimum and maximum phases of solar cycle 23. We discuss results for particles with nuclear charge 5 ≤ Z ≤ 28 and typical energies between 50 and 500 MeV nucleon^(–1). We demonstrate that a detailed "leaky box" Galactic propagation model combined with a spherically symmetric solar modulation model gives a good (but not perfect) fit to the observed spectra by using a solar modulation parameter of φ = 325 MV at solar minimum and φ = 900 MV at solar maximum. Although our results are generally consistent with previous measurements from space-based and balloon-based missions, there are significant differences. The large geometrical acceptance and excellent charge resolution of the instrument result in the most detailed and statistically significant record of GCR Composition to date in this energy range. The measurements reported here serve as a high-precision baseline for continued studies of GCR Composition, solar modulation over the solar cycle, space radiation hazards, and other applications.

  • abundance measurements of zn ga ge se from the cosmic ray isotope spectrometer cris experiment on the Advanced Composition Explorer ace satellite
    Bulletin of the American Physical Society, 2009
    Co-Authors: W R Binns, A C Cummings, M H Israel, R A Leske, R A Mewaldt, G A De Nolfo, T T Von Rosenvinge, E C Stone, M E Wiedenbeck
    Abstract:

    The cosmic ray elemental abundances of _(30)Zn, _(31)Ga, _(32)Ge, and _(34)Se provide important tests of the model of the OB-association origin of galactic cosmic rays that has resulted from previous ACE measurements of the neon and iron isotopes and which appears to be confirmed by elemental abundances of Zn, Ga, Ge, and Se measured by the balloon-borne Trans-Iron Galactic Element Recorder (TIGER). These ultra-heavy (Z≥30) nuclei are very rare and require an instrument with a large product of geometrical factor and exposure time. We have measured these abundances using the CRIS instrument, which has a geometrical factor of about 250 cm^2sr, on the NASA-ACE spacecraft. Over the 11+ years since launch in 1997 we have collected ∼400 nuclei with Z≥30 over the energy range of ∼150 to 600 MeV/nucleon. These measured abundances relative to iron are presented and compared with those from the TIGER and HEAO-3 experiments. Our measurements are in reasonable agreement with the TIGER results and are consistent with an OB association origin of galactic cosmic rays.