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Topic: Cosmic ray

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In the News (Wed 20 Mar 19)

 NGDC/WDC STP, Boulder-Cosmic Rays
Cosmic rays also have an extreme energy range of incident particles, which have allowed physicists to study aspects of their field that can not be studied in any other way.
The portion of the cosmic ray spectrum that reaches the Earth's atmosphere is controlled by the geomagnetic cutoff which varies from a minimum (theoretically zero) at the magnetic poles to a vertical cosmic ray cutoff of about 15 GV (ranging from 13 to 17) in the equatorial regions.
The cosmic rays show an inverse relationship to the sunspot cycle because Sun's magnetic field is stronger during sunspot maximum and shields the Earth from cosmic rays.
www.ngdc.noaa.gov /stp/SOLAR/COSMIC_RAYS/cosmic.html   (1037 words)

 Cosmic ray - Wikipedia, the free encyclopedia
In astrophysics, cosmic rays are radiation consisting of energetic particles originating beyond the Earth that impinge on the Earth's atmosphere.
Cosmic rays have been implicated in the triggering of electrical breakdown in lightning.
Cosmic rays have been expirementally determined to be a potential modulating factor in cloud formation and by theoretical extrapolation to be a contributor of global warming.
en.wikipedia.org /wiki/Cosmic_ray   (1846 words)

 Terrestrial cosmic ray intensities
Cosmic rays were first discovered because of the dogged curiosity of one man to explain a minor scientific irritation.
Cosmic rays became the source of wild speculation for the next twenty years because of their exponential increase in flux with height.
Cosmic rays are charged particles which interact with the geomagnetic field so that their trajectory is constantly curving; see Figure 9.
www.research.ibm.com /journal/rd/421/ziegler.html   (7636 words)

 Cosmic Rays   (Site not responding. Last check: 2007-10-13)
Cosmic ray ions, on the other hand, may be trapped by weak magnetic fields in the galaxy--trapped not forever, because sooner or later they hit an atom of the rarefied gas which fills the void between stars, but for a period of the order of 10 million years.
If cosmic ray ions stay around (on the average) 1000 times longer than starlight, their source only needs 1/1000 of the energy output of the stars to match the intensity of starlight.
Cosmic ray ions at the top of the energy range produce in the atmosphere showers of many millions of fragments, covering many acres, and their more energetic fragments register even in deep mines, a mile underground.
www-spof.gsfc.nasa.gov /Education/wcosray.html   (1989 words)

 SNR and Cosmic Ray Acceleration
Cosmic rays are the atomic nuclei (mostly protons) and electrons that are observed to strike the Earth's atmosphere with exceedingly high energies.
Although you may never yourself be bombarded by a primary cosmic ray (we are shielded from them by the Earth's magnetosphere), we are bombarded all the time by the secondary cascades of cosmic rays that are created when cosmic rays interact with Earth's atmosphere.
Cosmic rays produce Carbon 14, a small source of radiation but one which is critical for dating (for example establishing the age of fossils).
imagine.gsfc.nasa.gov /docs/features/topics/snr_group/cosmic_rays.html   (2441 words)

 Cosmic Ray History Encoded In Abundances Of Light Elements
Cosmic rays are particles -- mostly protons -- that bombard Earth at nearly the speed of light.
The traditional view is that cosmic rays are particles of the interstellar medium that were ionized and accelerated by a supernova shock wave.
Cosmic rays are believed to be one of the main contributors to slight genetic damage, so they may well play a part in our evolution.
business.fortunecity.com /rowling/167/SuperNovae/CosmicWaves.html   (3425 words)

 Cosmic Rays - Richard Mewaldt
Cosmic rays are high energy charged particles, originating in outer space, that travel at nearly the speed of light and strike the Earth from all directions.
Most cosmic rays are the nuclei of atoms, ranging from the lightest to the heaviest elements in the periodic table.
Cosmic rays are also a hazard to electronic instrumentation in space; impacts of heavily-ionizing cosmic ray nuclei can cause computer memory bits to "flip" or small microcircuits to fail.
www.srl.caltech.edu /personnel/dick/cos_encyc.html   (1485 words)

 Cosmic Rays
The composition of cosmic rays is important because cosmic rays are a direct sample of matter from outside the solar system and contain elements that are much too rare to be seen in spectroscopic lines from other stars.
If the cosmic rays have stayed in the Galaxy, the amount of matter that they have passed through divided by the average density of interstellar space (about one atom per cubic centimeter) gives the "age" of cosmic rays.
Cosmic rays spend a large fraction of their time in the low density galactic halo, bouncing back and forth through the galactic disk many times.
imagine.gsfc.nasa.gov /docs/science/know_l2/cosmic_rays.html   (776 words)

 Cosmic Ray Modulation
Cosmic rays enter the heliosphere due to random motions and diffuse inward toward the Sun, gyrating around the interplanetary magnetic field (IMF) and scattering at irregularities in the field.
Thus Equation 4 is an equation explicitly representing the transport of cosmic rays in the heliosphere by convection, diffusion and drift.
It is also apparent from Figure 4 that the cosmic ray peaks at solar minimum alternate from sharply peaked in the A<0 polarity state to flat topped in the A>0 state.
www.atnf.csiro.au /pasa/18_1/duldig/paper/node5.html   (4430 words)

 Galactic cosmic ray - Wikipedia, the free encyclopedia
Galactic cosmic rays differ in their composition and origin from solar cosmic rays, which are mostly protons and helium nuclei accelerated by solar activity.
The HEAO Heavy Nuclei Experiment, launched in 1979, collected only about 100 cosmic rays between element 75 and element 87 (the group of elements that includes platinum, mercury, and lead), in almost a year and a half of flight, and it was much bigger than most scientific instruments flown by NASA today.
Because the cosmic rays eventually escape the supernova remnant, they can only be accelerated up to a certain maximum energy, which depends upon the size of the acceleration region and the magnetic field strength.
en.wikipedia.org /wiki/Galactic_cosmic_ray   (876 words)

 Cosmic rays [Oulu]   (Site not responding. Last check: 2007-10-13)
Cosmic ray particles are travelling very close to the speed of light, and the most energetic particle ever observed had about 20 Joules of kinetic energy (equivalent to the energy of a fast shot ball).
The acceleration of the cosmic rays to observed energies is still partly an open question, especially at the ultra high energy range.
Cosmic rays are creating the same, harmfull effects in near space around the Earth as are the radiation belts and, in addition, affect radio communication in polar regions (see also space weather).
www.oulu.fi /~spaceweb/textbook/crays.html   (349 words)

 High Energy Cosmic Rays (SLAC VVC)
These primary cosmic rays generally do not make it through the earth's atmosphere, and constitute only a small fraction of what we can measure using a suitable set of particle detectors at the earth's surface.
The cosmic rays we are interested in at this web site have a much higher energy than those from the sun.
The Cosmic Ray Detector consists of three pairs of scintillator panels for muon detection.
www2.slac.stanford.edu /vvc/cosmicrays/default.htm   (303 words)

 An Introduction to Cosmic Ray Research   (Site not responding. Last check: 2007-10-13)
Cosmic ray research began in 1912 when Victor Hess and two assistants flew in a balloon to an altitude of about 16,000 ft. and discovered evidence of a very penetrating radiation coming from outside our atmosphere.
In reconstructing the history of cosmic rays, we are actually investigating events and processes in the far reaches of space.
The Particle Astrophysics Lab (PAL) studies cosmic rays using a magnetic spectrometer which is carried by helium balloon (unmanned) to an altitude of 120,000 ft. This allows PAL to observe cosmic rays before they interact with the earth's atmosphere.
www.ece.nmsu.edu /pal/cosmicrays.html   (537 words)

 Cosmic Rays - MariachiWiki
Cosmic rays are particles (maily consisted of protons) that are produced in cosmological events.
Thus MARIACHI is unique not only for being on the forefront of cosmic ray detection techniques, but also for its incorporation of a diverse and interdisciplinary group of scientists, educators, and students in a large collaboration for the support of cutting-edge research.
Nice introductions to Ultra High Energy Cosmic rays (UHECR)- the goal of the MARIACHI experiment- can be found at the University of Adelaide site, and the University of Leeds web site, which operated the Haverah Park Ground Array for many years.
www-mariachi.physics.sunysb.edu /wiki/index.php/Cosmic_Rays   (1204 words)

 ASCA: Cosmic-Rays
Cosmic rays were discovered in 1912 by the Austrian physicist Victor Hess, who subsequently received the Nobel Prize in Physics for that work.
Ever since their discovery, scientists have debated where cosmic rays come from and how ordinary subatomic particles can be accelerated to such high speeds.
The cosmic rays are accelerated in the two regions that glow with synchrotron radiation, the physicists concluded.
heasarc.gsfc.nasa.gov /docs/asca/science/cosmic.html   (699 words)

 Pierre Auger Observatory   (Site not responding. Last check: 2007-10-13)
While cosmic rays with low to moderate energies are well understood, those with extremely high energies remain mysterious.
Cosmic rays are charged particles (usually a proton or a heavy nucleus) that constantly rain down on us from space.
When a cosmic ray particle reaches Earth, it collides with a nucleus high in the atmosphere, producing many secondary particles, which share the original primary particle's energy.
www.auger.org   (211 words)

 [No title]   (Site not responding. Last check: 2007-10-13)
The highest energy cosmic rays are very rare (less than one hits a square kilometre of the Earth's surface each century).
A small fraction (0.1%) of cosmic rays are photons (in the form of gamma-rays).
These gamma-ray photons are important when trying to find the origin of cosmic rays since they have no electrical charge and so arrive at the Earth undeflected by the galactic magnetic field.
www.ast.leeds.ac.uk /haverah/cosrays.shtml   (311 words)

Cosmic rays are ionized particles from extraterrestrial sources traveling very close to the speed of light.
The IPST Cosmic Physics Group is working mainly on space-based experiments to resolve the shapes of the cosmic-ray H, He, and heavier nuclei energy spectra at energies approaching 10^15 eV.
The data from these projects are used to search for signatures of exotic matter (dark matter and cosmological antimatter), to investigate cosmic ray transport processes, and to quantify the charge-sign dependence of solar modulation.
cosmicray.umd.edu /homepage   (281 words)

 The Cosmic Ray Isotope Spectrometer
Galactic cosmic rays (GCRs) consist of energetic electrons and nuclei which are a direct sample of material from far beyond the solar system.
Many of the isotopes that will be collected by CRIS provide other information about the mechanisms of cosmic ray propagation (the study of the processes cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere).
In CRIS, energy information about the cosmic ray particles is collected by the 4 stacks of thick silicon detectors (shown as A-D), while the trajectory of the particles are determined by the Scintillating Optical Fiber Trajectory (SOFT) system.
www.srl.caltech.edu /ACE/CRIS_SIS/cris.html   (790 words)

 USATODAY.com - Sun's magnetic flip affects cosmic ray penetration   (Site not responding. Last check: 2007-10-13)
Since 1954, solar scientists have known that the sun's magnetic field, or heliosphere, shields the solar system from the full effects of cosmic rays, energetic atomic particles from space.
Cosmic rays are thought to play a role in initiating changes in the upper atmosphere that affect Earth's weather, sparking increased interest in their occurrence among scientists.
It found similar alignments of cosmic rays and so-called coronal mass ejections from the sun, powerful eruptions of the material that makes stars that increase alongside sunspots during the solar cycle.
www.usatoday.com /news/science/astro/2001-04-10-cosmic-rays.htm   (527 words)

 Cosmic Ray origins
The origin of cosmic rays remains a long-standing mystery in contemporary astrophysics.
Scientists suspect that cosmic rays -- essentially atomic particles that bombard the earth at nearly light speed -- are hurled through space to such great speeds by the shock waves of exploding stars, called supernovae.
Today's results, however, provide the first observational evidence of supernovae producing cosmic ray protons, which are a hundred times more common and a much heavier form of cosmic ray.
www.hartrao.ac.za /news/990915cosmicrays/cosmic.html   (781 words)

 Cosmic Rays
It is thought that the cosmic rays represent a mixture of interstellar material enriched with matter from evolved stars, such as supernovas and perhaps Wolf-Rayet stars.
Gamma-ray surveys (conducted by Earth-orbiting satellites) indicate that cosmic rays are strongly concentrated in the disk of the Milky Way Galaxy with a much smaller percentage in the surrounding halo.
From the early 1930s to the 1950s, cosmic rays played a critical role in the scientific study of the atomic nucleus and its components, for they were the only source of high-energy particles.
abyss.uoregon.edu /~js/glossary/cosmic_rays.html   (1121 words)

 NASA's Cosmicopia -- Cosmic Rays (via CobWeb/3.1 planetlab2.netlab.uky.edu)   (Site not responding. Last check: 2007-10-13)
Cosmic rays don't take pretty pictures, but studying the quantity and type of these particles helps us to understand the acceleration processes involved and to measure the composition of the Sun, as well as sources at the far distant reaches of the galaxy.
Some of the nuclei in the gas are accelerated to cosmic ray speeds, possibly by the shock waves from supernovae (e).
Cosmic ray acceleration could also occur directly as the supernova is ejecting matter into interstellar space, as in (d).
helios.gsfc.nasa.gov.cob-web.org:8888 /cosmic.html   (1395 words)

 CNN.com - Report: Cosmic rays influence climate change - July 31, 2002
The number of cosmic rays that strike Earth depends to some degree on the sun.
Yu said that observations of global warming this century have corresponded with lowered cosmic ray intensities.
In any case, Yu proposes that cosmic rays help stoke the formation of dense clouds in the lower atmosphere while having a little or negative affect on cloud cover in the upper atmosphere.
www.cnn.com /2002/TECH/space/07/31/earth.rays/index.html   (344 words)

 Cosmic Ray Detector - Muon Detector - Counting particles from space - Myon Particle Detector
Most cosmic rays are protons, which are abundant in the universe.
Primary cosmic rays are particles such as a single proton (nuclei of hydrogen; about 90% of all cosmic rays) up to an iron nucleus and beyond, but being typically protons and alpha particles (identical to helium nucleii; majority of the remaining 10%) traveling through the interstellar medium.
When these primary cosmic rays hit Earth's atmosphere at around 30,000m above the surface, the impacts cause nuclear reactions which produce pions.
www.cosmicrays.org   (479 words)

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