The isotopic composition of cosmic-ray B, C, N, and O - Evidence for an overabundance of O-18

Gibner, P. S.; Mewaldt, R. A.; Schindler, S. M.; Stone, E. C.; Webber, W. R.

doi:10.1086/186405

Cited by 20 publications

(7 citation statements)

References 10 publications

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“…Figures 17 and 18 show the ISOMAX lithium and boron isotopic ratios, respectively, at TOA in the TOF regime. Also included in the figures are predictions of a diffusive-halo model similar to the one used for the beryllium results ) and the results of other experiments (de Nolfo et al 2003;Webber et al 1977Webber et al , 2002Ahlen et al 2000;Gibner et al 1992;Krombel & Wiedenbeck 1988;Soutoul et al 1983;Smith & McDonald 1981;Webber & Kish 1979;Buffington et al 1978;Dwyer 1978;Hagen et al 1977;Garcia-Munoz et al 1975, 1977.…”

Section: Resultsmentioning

confidence: 99%

Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX

Hams

Barbier

Bremerich

et al. 2004

ApJ

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133

108

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The Isotope Magnet Experiment (ISOMAX), a balloon-borne superconducting magnet spectrometer, was designed to measure the isotopic composition of the light isotopes (3 Z 8) of cosmic radiation up to 4 GeV nucleon À1 with a mass resolution of better than 0.25 amu by using the velocity versus rigidity technique. To achieve this stringent mass resolution, ISOMAX was composed of three major detector systems: a magnetic rigidity spectrometer with a precision drift chamber tracker in conjunction with a three-layer time-of-flight system, and two silica-aerogel Cerenkov counters for velocity determination. A special emphasis of the ISOMAX program was the accurate measurement of radioactive 10 Be with respect to its stable neighbor isotope 9 Be, which provides important constraints on the age of cosmic rays in the Galaxy. ISOMAX had its first balloon flight on 1998 August 4-5 from Lynn Lake, Manitoba, Canada. Thirteen hours of data were recorded during this flight at a residual atmosphere of less than 5 g cm À2 . The isotopic ratio at the top of the atmosphere for 10 Be/ 9 Be was measured to be 0:195 AE 0:036 (statistical) AE 0:039 (systematic) between 0.26 and 1.03 GeV nucleon À1 and 0:317 AE 0:109 (statistical) AE 0:042 (systematic) between 1.13 and 2.03 GeV nucleon À1 . This is the first measurement of its kind above 1 GeV nucleon À1 . ISOMAX results tend to be higher than predictions from current propagation models. In addition to the beryllium results, we report the isotopic ratios of neighboring lithium and boron in the energy range of the time-of-flight system (up to $1 GeV nucleon À1 ). The lithium and boron ratios agree well with existing data and model predictions at similar energies.

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Section: Resultsmentioning

confidence: 99%

Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX

Hams

Barbier

Bremerich

et al. 2004

ApJ

Self Cite

133

108

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“…Over the geomagnetic poles (latitudes A > 60~ the isotopic ratios of these elements vary with energy. At energies > 50 MeV/nuc, where GCRs dominate, most of the observed 15N and 180 is produced by cosmic ray spallation during transport through the galaxy and is not directly indicative of either the GCR source or the local ISM abundances (see e.g., Gibner et al, 1992). ttowever, most of the observed 22Ne originates in the cosmic ray source.…”

Section: Anomalous Cosmic Ray Isotopic Compositionmentioning

confidence: 99%

“…Instruments to be flown on the Advanced Composition Explorer (ACE) in 1997 will extend isotope measurements to lower energies (e.g., 5 to 15; MeV/nuc), where the ACR flux is greater and GCR contamination is minimized, with a collecting Previous data are from the compilation by Mewaldt et al (1984), and from Krombel and Wiedenbeck (1988), Garcia-Munoz et al (1993), Connell and Simpson (1993a,b), DuVemois et al (1993), Gibner et al (1992), Lukasiak et al (1994), Webber et al (1996), andCummings et al (1991). power > 30 times that on SAMPEX. However, ACE will not be able to make use of geomagnetic filtering as the satellite will be stationed outside the magnetosphere.…”

Section: Anomalous Cosmic Ray Isotopic Compositionmentioning

confidence: 99%

The isotopic composition of anomalous cosmic rays from sampex

Leske¹,

Mewaldt²,

Cummings³

et al. 1996

Space Sci Rev

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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, 180/160 < 0.0034, and 22Ne/2~ = 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/2~ measurements from various sources implies that GCRs are not simply an accelerated sample of the local interstellar medium.

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“…The analysis in the 9–12 m / z range allows for the highlighting of the presence of boron in the anode 312B sample while no peak was observed for the anode 0B sample. The spectrum of the boron-impregnated sample exhibits two peaks: one at m / z = 11 and the other at m / z = 10, the isotope of boron with a ratio of 20% …”

Section: Resultsmentioning

confidence: 99%

Characterization of Carbon Anode Protected by Low Boron Level: An Attempt To Understand Carbon–Boron Inhibitor Mechanism

Ishak

Laroche

Lamonier

et al. 2017

ACS Sustainable Chem. Eng.

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Several chemical reactions occur during the electrolysis of alumina in the Hall−Héroult process resulting in a significant overconsumption of the carbon anode. Carbon oxidation with oxygen is one of these reactions. The inhibition of this reaction by the application of protective layers on the anode can be an effective technique to reduce carbon consumption. Boron impregnation was shown to suppress this reaction. In this study, very low boron content has been impregnated on the anode, and several characterization methods have been performed to understand the protection mechanism of such a low boron concentration during the oxidation reaction of anodes. An air reactivity test of boron-impregnated anodes has been performed at temperatures between 400 and 600 °C. The samples were characterized using XPS, Raman spectroscopy, XRD, XRF, porosimetry, and thermogravimetric analysis (TGA). TGA revealed that the total number of interactions between oxygen atoms and carbon active sites was reduced, decreasing the pre-exponential factor. Time-offlight secondary ion mass spectroscopy (ToF-SIMS) has been employed as a highly sensitive surface characterization method to identify chemical forms of boron on the anode. It has been confirmed that boron blocks active sites of carbon by creating boron−carbon bonds, thus reducing the interaction of carbon active sites with oxygen.

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The isotopic composition of cosmic-ray B, C, N, and O - Evidence for an overabundance of O-18

Cited by 20 publications

References 10 publications

Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX

Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX

The isotopic composition of anomalous cosmic rays from sampex

Characterization of Carbon Anode Protected by Low Boron Level: An Attempt To Understand Carbon–Boron Inhibitor Mechanism

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The isotopic composition of cosmic-ray B, C, N, and O - Evidence for an overabundance of O-18

Cited by 20 publications

References 10 publications

Measurement of the Abundance of Radioactive10Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon−1with the Balloon‐borne Instrument ISOMAX

Measurement of the Abundance of Radioactive10Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon−1with the Balloon‐borne Instrument ISOMAX

The isotopic composition of anomalous cosmic rays from sampex

Characterization of Carbon Anode Protected by Low Boron Level: An Attempt To Understand Carbon–Boron Inhibitor Mechanism

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Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX

Measurement of the Abundance of Radioactive¹⁰Be and Other Light Isotopes in Cosmic Radiation up to 2 GeV Nucleon⁻¹with the Balloon‐borne Instrument ISOMAX