共查询到20条相似文献,搜索用时 0 毫秒
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Fleischer RL Price PB Walker RM Filz RC Fukui K Friedlander MW Holeman E Rajan RS Tamhane AS 《Science (New York, N.Y.)》1967,155(3759):187-189
Cosmic ray nuclei have been observed with the use of plastic trackdetecting solids in satellites and high-altitude balloon flights. Nuclear emulsions in the stacks of plastic sheets allowed the positive identification of cosmic raynuclei as light as nitrogen. The most striking new information was the failure to observe relativistic iron nuclei, a result which has led to an advance in the understanding of track registration criteria. 相似文献
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Amenomori M Ayabe S Bi XJ Chen D Cui SW Danzengluobu Ding LK Ding XH Feng CF Feng Z Feng ZY Gao XY Geng QX Guo HW He HH He M Hibino K Hotta N Hu H Hu HB Huang J Huang Q Jia HY Kajino F Kasahara K Katayose Y Kato C Kawata K Labaciren Le GM Li AF Li JY Lou YQ Lu H Lu SL Meng XR Mizutani K Mu J Munakata K Nagai A Nanjo H Nishizawa M Ohnishi M Ohta I Onuma H Ouchi T Ozawa S Ren JR Saito T Saito TY Sakata M Sako TK Sasaki T Shibata M Shiomi A Shirai T Sugimoto H Takita M Tan YH Tateyama N Torii S 《Science (New York, N.Y.)》2006,314(5798):439-443
The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments. 相似文献
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LIBBY WF 《Science (New York, N.Y.)》1955,122(3158):57-58
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Ray T 《Science (New York, N.Y.)》2010,330(6008):1184-1185
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Gaisser TK 《Science (New York, N.Y.)》1990,247(4946):1049-1056
Compact regions in the Milky Way, such as accreting degenerate binary stars, may be sites of acceleration of particles with energies far greater than produced at any man-made accelerator, present or proposed. If so, they would emit characteristic neutral radiation of ultra-high energy, which might be strong enough to be detectable at Earth. The quest for these faint but energetic signals is the focus of more than 50 large, ground-based experiments that are looking for high energy photons or neutrinos from point sources in our galaxy and beyond. Several sources have been claimed, but the signals appear to have unexpected and puzzling features that must be clarified before the field can settle into a routine phase of systematic investigation. In the meantime, the potentially profound implications for particle physics, as well as astrophysics, make this field one of intense activity. 相似文献
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Existence of magnesium-28 (half-life, 21.3 hours) produced by cosmic rays in rain at concentrations of 1.7 and 6.1 x 10(-1) atoms per milliliter was established radiochemically by isolating this nuclide from several hundred liters of rain samples collected at Fayetteville, Arkansas. 相似文献
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Three-dimensional simulations of the heliospheric modulation of galactic cosmic ray protons show that corotating variations in the intensity can persist to quite high heliographic latitudes. Variations are seen at latitudes considerably higher than the maximum latitude extension of the heliographic current sheet, in regions where the solar wind velocity and magnetic field show no significant variation. Similar conclusions may apply also to lower energy particles, which may be accelerated at lower latitudes. Cosmic ray variations caused by corotating interaction regions present at low heliographic latitudes can propagate to significantly higher latitudes. 相似文献
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Pierre Auger Collaboration Abraham J Abreu P Aglietta M Aguirre C Allard D Allekotte I Allen J Allison P Alvarez C Alvarez-Muñiz J Ambrosio M Anchordoqui L Andringa S Anzalone A Aramo C Argirò S Arisaka K Armengaud E Arneodo F Arqueros F Asch T Asorey H Assis P Atulugama BS Aublin J Ave M Avila G Bäcker T Badagnani D Barbosa AF Barnhill D Barroso SL Bauleo P Beatty J Beau T Becker BR Becker KH Bellido JA Benzvi S Berat C Bergmann T Bernardini P Bertou X Biermann PL Billoir P Blanch-Bigas O 《Science (New York, N.Y.)》2007,318(5852):938-943
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources. 相似文献
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Sigl G 《Science (New York, N.Y.)》2001,291(5501):73-79
The origin of cosmic rays is one of the major unresolved questions in astrophysics. In particular, the highest energy cosmic rays observed have macroscopic energies up to several 10(20) electron volts and thus provide a probe of physics and astrophysics at energies unattained in laboratory experiments. Theoretical explanations range from astrophysical acceleration of charged particles, to particle physics beyond the established standard model, and processes taking place at the earliest moments of our universe. Distinguishing between these scenarios requires detectors with effective areas in the 1000-square-kilometer range, which are now under construction or in the planning stage. Close connections with gamma-ray and neutrino astrophysics add to the interdisciplinary character of this field. 相似文献
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The ratios of fluxes of heavy cosmic-ray nuclei [(30 = Z = 40)/(20 < Z = 28), where Z is the atomic number], based on studies of meteorites and lunar samples, show little variation with time, distance in the solar system (1 to 3 astronomical units), or kinetic energy (30 to 2000 megaelectron volts per nucleon). Samples exposed for time intervals of 10(3) to 10(8) years show that the variations in the flux of 30 = Z = 40 nuclei relative to that of the iron group nuclei (20 < Z = 28) have remained within the range of (1.3 +/- 0.6) x 10(-3) during the last billions of years, thus indicating a remarkable similarity in the elemental composition of sources responsible for these nuclei in the cosmic radiation. 相似文献
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Beaujean R Schmidt M Enge W Siegmon G Krause J Fischer E 《Science (New York, N.Y.)》1984,225(4658):193-195
A stack of plastic nuclear track detectors was exposed to heavy cosmic rays on the pallet of Spacelab 1. Some layers of the stack were rotated with respect to the main stack to determine the arrival time of the particles. After return of the stack the latent particle tracks are revealed by chemical etching. Under the optical microscope the charge, mass, energy, and impact direction of the particles can be deduced from the track geometry. 相似文献
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The energy spectrum of solar cosmic-ray particles of the iron group has been determined for the first time over the energy range from 1 to 100 million electron volts per nucleon by the use of glass removed from the Surveyor 3 spacecraft. The difference between the observed (energy)(-3) spectrum and the limiting spectrum derived previously from tracks in lunar rocks gives an erosion rate of 0 to 2 angstroms per year. High-energy fission of lead, induced by galactic cosmicray protons and alpha particles, has also been observed. 相似文献
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Ackermann M Ajello M Allafort A Baldini L Ballet J Barbiellini G Bastieri D Belfiore A Bellazzini R Berenji B Blandford RD Bloom ED Bonamente E Borgland AW Bottacini E Brigida M Bruel P Buehler R Buson S Caliandro GA Cameron RA Caraveo PA Casandjian JM Cecchi C Chekhtman A Cheung CC Chiang J Ciprini S Claus R Cohen-Tanugi J de Angelis A de Palma F Dermer CD do Couto E Silva E Drell PS Dumora D Favuzzi C Fegan SJ Focke WB Fortin P Fukazawa Y Fusco P Gargano F Germani S Giglietto N Giordano F 《Science (New York, N.Y.)》2011,334(6059):1103-1107
The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little of their escape from the shock and their evolution through the turbulent medium surrounding massive stars. Gamma rays can probe their spreading through the ambient gas and radiation fields. The Fermi Large Area Telescope (LAT) has observed the star-forming region of Cygnus X. The 1- to 100-gigaelectronvolt images reveal a 50-parsec-wide cocoon of freshly accelerated cosmic rays that flood the cavities carved by the stellar winds and ionization fronts from young stellar clusters. It provides an example to study the youth of cosmic rays in a superbubble environment before they merge into the older Galactic population. 相似文献
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