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  • 1
    Electronic Resource
    Electronic Resource
    Composition of anomalous cosmic rays and implications for the heliosphere (1996)
    Springer
    Space science reviews 78 (1996), S. 117-128 
    Details
    ISSN: 1572-9672
    Keywords: abundances ; anomalous cosmic rays ; Voyager ; interstellar medium ; heliosphere ; solar wind termination shock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We use energy spectra of anomalous cosmic rays (ACRs) measured with the Cosmic Ray instrument on the Voyager 1 and 2 spacecraft during the period 1994/157-313 to determine several parameters of interest to heliospheric studies. We estimate that the strength of the solar wind termination shock is 2.42 (−0.08, +0.04). We determine the composition of ACRs by estimating their differential energy spectra at the shock and find the following abundance ratios: H/He = 5.6 (−0.5, +0.6), C/He = 0.00048 ± 0.00011, N/He = 0.011 ± 0.001, O/He = 0.075 ± 0.006, and Ne/He = 0.0050 ± 0.0004. We correlate our observations with those of pickup ions to deduce that the long-term ionization rate of neutral nitrogen at 1 AU is ∼ 8.3 × 10−7 s−1 and that the charge-exchange cross section for neutral N and solar wind protons is ∼ 1.0 × 10−15 cm2 at 1.1 keV. We estimate that the neutral C/He ratio in the outer heliosphere is 1.8(−0.7, +0.9) × 10−5. We also find that heavy ions are preferentially injected into the acceleration process at the termination shock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170798
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  • 2
    Electronic Resource
    Electronic Resource
    The isotopic composition of anomalous cosmic rays from sampex (1996)
    Springer
    Space science reviews 78 (1996), S. 149-154 
    Details
    ISSN: 1572-9672
    Keywords: abundances ; isotopes ; anomalous cosmic rays ; SAMPEX ; neon ; interstellar medium ; heliosphere ; trapped heavy ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the anomalous cosmic ray (ACR) isotopic composition have been made in three regions of the magnetosphere accessible from the polar Earth orbit of SAMPEX, including the interplanetary medium at high latitudes and geomagnetically trapped ACRs. At those latitudes where ACRs can penetrate the Earth's magnetic field while fully stripped galactic cosmic rays (GCRs) of similar energies are excluded, a pure ACR sample is observed to have the following composition: 15N/N 〈 0.023, 18O/16O 〈 0.0034, and 22Ne/20Ne = 0.077(+0.085, −0.023). We compare our values with those found by previous investigators and with those measured in other samples of solar and galactic material. In particular, a comparison of 22Ne/20Ne measurements from various sources implies that GCRs are not simply an accelerated sample of the local interstellar medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170801
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  • 3
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    The Super-TIGER Instrument to Probe Galactic Cosmic Ray Origins (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: Super-TIGER (Super Trans-Iron Galactic Element Recorder) is under construction for the first of two planned Antarctic long-duration balloon flights in December 2012. This new instrument will measure the abundances of ultra-heavy elements (30Zn and heavier), with individual element resolution, to provide sensitive tests of the emerging model of cosmic-ray origins in OB associations and models of the mechanism for selection of nuclei for acceleration. Super-TIGER builds on the techniques of TIGER, which produced the first well-resolved measurements of elemental abundances of the elements 31Ga, 32Ge, and 34Se. Plastic scintillators together with acrylic and silica-aerogel Cherenkov detectors measure particle charge. Scintillating-fiber hodoscopes track particle trajectories. Super-TIGER has an active area of 5.4 sq m, divided into two independent modules. With reduced material thickness to decrease interactions, its effective geometry factor is approx.6.4 times larger than TIGER, allowing it to measure elements up to 42Mo with high statistical precision, and make exploratory measurements up to 56Ba. Super-TIGER will also accurately determine the energy spectra of the more abundant elements from l0Ne to 28Ni between 0.8 and 10 GeV/nucleon to test the hypothesis that microquasars or other sources could superpose spectral features. We will discuss the implications of Super-TIGER measurements for the study of cosmic-ray origins and will present the measurement technique, design, status, and expected performance, including numbers of events and resolution. Details of the hodoscopes, scintillators, and Cherenkov detectors will be given in other presentations at this conference.
    Keywords: Astrophysics
    Type: GSFC.ABS.5158.2011 , GSFC.O.5159.2011 , 32nd International Cosmic Ray Conference/Waseda University; 11-18 Aug. 211; Beijing; China
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  • 4
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    Solar Cycle Dynamics of Solar, Magnetospheric, and Heliospheric Particles, and Long-Term Atmospheric Coupling: SAMPEX (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This report summarizes science analysis activities by the SAMPEX mission science team during the period during the period July 1, 1997 through July 1, 1997. Bibliographic entries for 1996 and 1997 to date (July 1997) are included. The SAMPEX science team was extremely active, with 27 articles published or submitted to refereed journals, 17 papers published in their entirety in Conference Proceedings, and 74 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings, as well as other activities of the team.
    Keywords: Astrophysics
    Type: NASA-CR-204981 , NAS 1.26:204981
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  • 5
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    Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Flare (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We discuss observations of energetic neutral hydrogen atoms (ENAs) from a solar flare/coronal mass ejection event reported by Mewaldt et al. (2009). The observations were made during the 5 December 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV particles arriving from the Sun. The derived solar emission profile, arrival directions, and energy spectrum all show that the 〈5 MeV particles were due to energetic neutral hydrogen atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. CME-driven shock acceleration is also considered. Taking into account ENA losses, we conclude that the observed ENAs must have been produced in the high corona at heliocentric distances .2 solar radii.
    Keywords: Astrophysics
    Type: M09-0557 , 31st International Cosmic Ray Conference; Jul 07, 2009 - Jul 15, 2009; Lodz; Poland
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  • 6
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    Insights into the Galactic Cosmic-ray Source from the TIGER Experiment (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: We report results from 50 days of data accumulated in two Antarctic flights of the Trans-Iron Galactic Element Recorder (TIGER). With a detector system composed of scintillators, Cherenkov detectors, and scintillating optical fibers, TIGER has a geometrical acceptance of 1.7 sq m sr and a charge resolution of 0.23 cu at Iron. TIGER has obtained abundance measurements of some of the rare galactic cosmic rays heavier than iron, including Zn, Ga, Ge, Se, and Sr, as well as the more abundant lighter elements (down to Si). The heavy elements have long been recognized as important probes of the nature of the galactic cosmic-ray source and accelerator. After accounting for fragmentation of cosmic-ray nuclei as they propagate through the Galaxy and the atmosphere above the detector system, the TIGER source abundances are consistent with a source that is a mixture of about 20% ejecta from massive stars and 80% interstellar medium with solar system composition. This result supports a model of cosmic-ray origin in OB associations previously inferred from ACE-CRIS data of more abundant lighter elements. These TIGER data also support a cosmic-ray acceleration model in which elements present in interstellar grains are accelerated preferentially compared with those found in interstellar gas.
    Keywords: Astrophysics
    Type: 31st International Cosmic Ray Conference/International Union of Pure and Applied Physics (IUPAP); Jul 07, 2009 - Jul 15, 2009; Lodz; Poland
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  • 7
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    The Energetic Trans-Iron Cosmic-ray Experiment (ENTICE) (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The ENTICE experiment is one of two instruments that comprise the "Orbiting Astrophysical Spectrometer in Space (OASIS)", which is presently undergoing a NASA "Astrophysics Strategic Mission Concept Study". ENTICE is designed to make high precision measurements of the abundances of individual elements from neon through the actinides and, in addition, will search for possible superheavy nuclei in the galactic cosmic rays. The ENTICE instrument utilizes silicon detectors, aerogel and acrylic Cherenkov counters, and a scintillating optical fiber hodoscope to measure the charge and energy of these ultra-heavy nuclei for energies greater than 0.5 GeV/nucleon. It is a large instrument consisting of four modules with a total effective geometrical factor of approx.20 sq m sr. Measurements made in space for a period of three years with ENTICE will enable us to determine if cosmic rays include a component of recently synthesized transuranic elements (Pu-94 and Cm-96), to measure the age of that component, and to test the model of the OB association origin of galactic cosmic rays. Additionally, these observations will enable us to study how diffusive shock acceleration of cosmic rays operates differently on interstellar grains and gas. Keywords: cosmic rays Galaxy:abundances
    Keywords: Astrophysics
    Type: M09-0518 , 31st International Cosmic Ray Conference; Jul 07, 2009 - Jul 05, 2009; Lodz; Poland
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  • 8
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    Solar cycle dynamics of solar, magnetospheric, and heliospheric particles, and long-term atmospheric coupling: SAMPLEX (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This report summarizes science analysis activities by the SAMPEX mission science team during the period during the period July 1, 1995 through July 1, 1996. Bibliographic entries for 1995 and 1996 to date (July 1996) are included. The SAMPEX science team was extremely active, with 20 articles published or submitted to refereed journals, 18 papers published in their entirety in Conference Proceedings, and 53 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings of anomalous cosmic rays, solar energetic particles, magnetospheric precipitating electrons, trapped H and He isotopes, and data analysis activities.
    Keywords: Astrophysics
    Type: NASA-CR-201539 , NAS 1.26:201539
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  • 9
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    Observations of the Li, Be, and B Isotopes and Constraints on Cosmic-ray Propagation (2007)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: The abundance of Li, Be, and B isotopes in galactic cosmic rays (GCR) between E=50-200 MeV/nucleon has been observed by the Cosmic Ray Isotope Spectrometer (CRIS) on NASA's ACE mission since 1997 with high statistical accuracy. Precise observations of Li, Be, B can be used to constrain GCR propagation models. We find that a diffusive reacceleration model with parameters that best match CRIS results (e.g. B/C, Li/C, etc) are also consistent with other GCR observations. A approx. 15-20% overproduction of Li and Be in the model predictions is attributed to uncertainties in the production cross-section data. The latter becomes a significant limitation to the study of rare GCR species that are generated predominantly via spallation.
    Keywords: Astrophysics
    Type: To appear in Journal of Advances in Space Research
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  • 10
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    Observation of the 60Fe Nucleosynthesis-Clock Isotope in Galactic Cosmic Rays (2016)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Iron-60 (60Fe) is a radioactive isotope in cosmic rays that serves as a clock to infer an upper limit on the time between nucleosynthesis and acceleration. We have used the ACE-CRIS instrument to collect 3.55 105 iron nuclei, with energies 195 to 500 megaelectron volts per nucleon, of which we identify 15 60Fe nuclei. The 60Fe56Fe source ratio is (7.5 2.9) 105. The detection of supernova-produced 60Fe in cosmic rays implies that the time required for acceleration and transport to Earth does not greatly exceed the 60Fe half-life of 2.6 million years and that the 60Fe source distance does not greatly exceed the distance cosmic rays can diffuse over this time, 1 kiloparsec. A natural place for 60Fe origin is in nearby clusters of massive stars.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN40722 , Science (ISSN 0036-8075) (e-ISSN 1095-9203); 352; 6286; 677-680
    Format: text
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