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W. R. Binns M. E. Wiedenbeck M. Arnould A. C. Cummings G. A. de Nolfo S. Goriely M. H. Israel R. A. Leske R. A. Mewaldt G. Meynet L. M. Scott E. C. Stone T. T. von Rosenvinge 《Space Science Reviews》2007,130(1-4):439-449
We have measured the isotopic abundances of neon and a number of other species in the galactic cosmic rays (GCRs) using the
Cosmic Ray Isotope Spectrometer (CRIS) aboard the ACE spacecraft. Our data are compared to recent results from two-component
(Wolf–Rayet material plus solar-like mixtures) Wolf–Rayet (WR) models. The three largest deviations of galactic cosmic ray
isotope ratios from solar-system ratios predicted by these models, 12C/16O, 22Ne/20Ne, and 58Fe/56Fe, are very close to those observed. All of the isotopic ratios that we have measured are consistent with a GCR source consisting
of ∼20% of WR material mixed with ∼80% material with solar-system composition. Since WR stars are evolutionary products of
OB stars, and most OB stars exist in OB associations that form superbubbles, the good agreement of our data with WR models
suggests that OB associations within superbubbles are the likely source of at least a substantial fraction of GCRs. In previous
work it has been shown that the primary 59Ni (which decays only by electron-capture) in GCRs has decayed, indicating a time interval between nucleosynthesis and acceleration
of >105 y. It has been suggested that in the OB association environment, ejecta from supernovae might be accelerated by the high
velocity WR winds on a time scale that is short compared to the half-life of 59Ni. Thus the 59Ni might not have time to decay and this would cast doubt upon the OB association origin of cosmic rays. In this paper we
suggest a scenario that should allow much of the 59Ni to decay in the OB association environment and conclude that the hypothesis of the OB association origin of cosmic rays
appears to be viable. 相似文献
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R.A. Mewaldt N.E. Yanasak M.E. Wiedenbeck A.J. Davis W.R. Binns E.R. Christian A.C. Cummings P.L. Hink R.A. Leske S.M. Niebur E.C. Stone T.T. Von Rosenvinge 《Space Science Reviews》2001,99(1-4):27-39
There are a number of radioactive clocks in the cosmic radiation that can be used to measure the time scales for cosmic ray processes in the Galaxy. With high-resolution isotope measurements available from ACE it is now possible to read these clocks with greatly improved accuracy and address key questions about the origin and lifetime of cosmic rays. This paper discusses the status of three such investigations. 相似文献
3.
M. E. Wiedenbeck W. R. Binns A. C. Cummings A. J. Davis G. A. de Nolfo M. H. Israel R. A. Leske R. A. Mewaldt E. C. Stone T. T. von Rosenvinge 《Space Science Reviews》2007,130(1-4):415-429
The galactic cosmic rays arriving near Earth, which include both stable and long-lived nuclides from throughout the periodic
table, consist of a mix of stellar nucleosynthesis products accelerated by shocks in the interstellar medium (ISM) and fragmentation
products made by high-energy collisions during propagation through the ISM. Through the study of the composition and spectra
of a variety of elements and isotopes in this diverse sample, models have been developed for the origin, acceleration, and
transport of galactic cosmic rays. We present an overview of the current understanding of these topics emphasizing the insights
that have been gained through investigations in the charge and energy ranges Z≲30 and E/M≲1 GeV/nuc, and particularly those using data obtained from the Cosmic Ray Isotope Spectrometer on NASA’s Advanced Composition
Explorer mission. 相似文献
4.
Stone E.C. Cohen C.M.S. Cook W.R. Cummings A.C. Gauld B. Kecman B. Leske R.A. Mewaldt R.A. Thayer M.R. Dougherty B.L. Grumm R.L. Milliken B.D. Radocinski R.G. Wiedenbeck M.E. Christian E.R. Shuman S. Trexel H. von Rosenvinge T.T. Binns W.R. Crary D.J. Dowkontt P. Epstein J. Hink P.L. Klarmann J. Lijowski M. Olevitch M.A. 《Space Science Reviews》1998,86(1-4):285-356
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 nucl−1, 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 ∼r250 cm2 sr for isotope measurements, and should accumulate ∼5×106 stopping heavy nuclei (Z>2) in two
years of data collection under solar minimum conditions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
D.A. Binns N. Rando L. Cacciapuoti 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
ESA technology reference studies are used as a process to identify key technologies and technical challenges of potential future missions not yet in the science programme. This paper reports on the study of the Fundamental Physics Explorer (FPE), a re-usable platform targeted to small missions testing fundamental laws of physics in space. The study addresses three specific areas of interest: special and general relativity tests based on atomic clocks, experiments on the Weak Equivalence Principle (WEP), and studies of Bose–Einstein condensates under microgravity conditions. Starting from preliminary science objectives and payload requirements, three reference missions in the small/medium class range are discussed, based on a re-adaptation of the LISA Pathfinder spacecraft. A 700/3600 km elliptic orbit has been selected to conduct clock tests of special and general relativity, a 700 km circular orbit to perform experiments on the Weak Equivalence Principle and to study Bose–Einstein condensates, each mission being based on a three-axis stabilised spacecraft. It was determined that adaptation of LISA Pathfinder would be required in order to meet the demands of the FPE missions. Moreover it was established that specific payload and spacecraft technology development would be required to realise such a programme. 相似文献
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