A few comments on your points aXis:
1) This is dependent on your geomagnetic position on Earth. The high energy cosmics go through it anyway and we are shielded from them by the atmosphere more than the weak magnetic field.
2)There's no neutrons in the primary cosmic rays since they decay AND neutrons *do* interact with matter a *lot*. The neutrons come from the interactions of charged particles with the atmosphere. They are the second highest dose inducer after muons at sea level, and the primary at an altitude of ~4km. You must be confusing them with neutrinos.http://www.triumf.ca/safety/rpt/rpt_4/no de3.html
3)There's not that many gamma-rays in the radiation that hits us on earth and they are mainly muons - which are charged particles and actually do some harm to us but not as much as the average amount of X-rays we get per year.
So the way I would put it is that we are transparent to the highest fluxes of particles (neutrinos) and that the radiation that reaches us from interactions of cosmic rays in the atmosphere induce lower doses than other ambient radioactivity sources..
There is an intrinsic limit to the highest energy of a particle that can travel through the cosmic background without interacting with it, called the GZK cutoff. Something like 10^20 eV or about 20 Joule. Radiation above this GZK cutoff can travel at most ~100-150 million light-years before losing energy in such interactions. Just for neighbours (the visible horizon is ~20 billion lightyears away)
Good point - the image is in the Nature paper that came out today
http://www.nature.com/cgi-taf/dynapage.taf?file=/n ature/journal/v432/n7013/index.html
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A few comments on your points aXis: 1) This is dependent on your geomagnetic position on Earth. The high energy cosmics go through it anyway and we are shielded from them by the atmosphere more than the weak magnetic field. 2)There's no neutrons in the primary cosmic rays since they decay AND neutrons *do* interact with matter a *lot*. The neutrons come from the interactions of charged particles with the atmosphere. They are the second highest dose inducer after muons at sea level, and the primary at an altitude of ~4km. You must be confusing them with neutrinos.http://www.triumf.ca/safety/rpt/rpt_4/no de3.html
3)There's not that many gamma-rays in the radiation that hits us on earth and they are mainly muons - which are charged particles and actually do some harm to us but not as much as the average amount of X-rays we get per year.
So the way I would put it is that we are transparent to the highest fluxes of particles (neutrinos) and that the radiation that reaches us from interactions of cosmic rays in the atmosphere induce lower doses than other ambient radioactivity sources..
There is an intrinsic limit to the highest energy of a particle that can travel through the cosmic background without interacting with it, called the GZK cutoff. Something like 10^20 eV or about 20 Joule. Radiation above this GZK cutoff can travel at most ~100-150 million light-years before losing energy in such interactions. Just for neighbours (the visible horizon is ~20 billion lightyears away)
Good point - the image is in the Nature paper that came out today http://www.nature.com/cgi-taf/dynapage.taf?file=/n ature/journal/v432/n7013/index.html