COSMIC RAY
A ray of radiation of extraterrestrial origin, consisting of one or more
charged particles such as protons, alpha particles, and larger atomic
nuclei. Cosmic rays entering the atmosphere collide with atoms,
producing secondary radiation, such as pions, muons, electrons, and
gamma rays. Cosmic rays (and secondary radiation) can be easily seen in a
cloud chamber.
The reigning explanation for cosmic rays has been that protons and other particles are accelerated by the leftovers of supernovas – the powerful explosions that occur when huge stars die. But new observations from Italy's space-based PAMELA cosmic ray detector appear to contradict that scenario and have researchers digging for a new explanation.
Cosmic rays are particles that hit Earth and come from outer space. Most of these particles are protons, some are the insides of helium (alpha particles), some are electrons (beta particles), gamma rays or photons and a tiny fraction are even heavier particles.
Some of these particles come from things that happen in the Sun and some come from all the way from unknown events in the farthest away parts of the universe. Cosmic rays can have as much energy as 1020 eV, far higher than the 1012 to 1013 eV that man-made particle accelerators can produce.
When cosmic ray particles enter the Earth's atmosphere they hit other particles, particles like oxygen and nitrogen. they then split apart into a shower of lighter particles, a so-called air shower.
The number of particles made in an air shower event can reach billions. All of the particles in the shower stay within about one degree of the first particle's path. Lots of different particles are made in collisions like this but lots of the time there are charged mesons (e.g. positive and negative pions and kaons). Cosmic rays are also the reason for the why we usually have a number of unstable isotopes in the Earth that does not change much even though those isotopes break into other elements. a good example is carbon-14, we always have the same number of carbon 14 particles because some cosmic rays react with elements like carbon-14 and make them unstable.
The reigning explanation for cosmic rays has been that protons and other particles are accelerated by the leftovers of supernovas – the powerful explosions that occur when huge stars die. But new observations from Italy's space-based PAMELA cosmic ray detector appear to contradict that scenario and have researchers digging for a new explanation.
Cosmic rays are particles that hit Earth and come from outer space. Most of these particles are protons, some are the insides of helium (alpha particles), some are electrons (beta particles), gamma rays or photons and a tiny fraction are even heavier particles.
Some of these particles come from things that happen in the Sun and some come from all the way from unknown events in the farthest away parts of the universe. Cosmic rays can have as much energy as 1020 eV, far higher than the 1012 to 1013 eV that man-made particle accelerators can produce.
When cosmic ray particles enter the Earth's atmosphere they hit other particles, particles like oxygen and nitrogen. they then split apart into a shower of lighter particles, a so-called air shower.
The number of particles made in an air shower event can reach billions. All of the particles in the shower stay within about one degree of the first particle's path. Lots of different particles are made in collisions like this but lots of the time there are charged mesons (e.g. positive and negative pions and kaons). Cosmic rays are also the reason for the why we usually have a number of unstable isotopes in the Earth that does not change much even though those isotopes break into other elements. a good example is carbon-14, we always have the same number of carbon 14 particles because some cosmic rays react with elements like carbon-14 and make them unstable.
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