GeeKay Posted May 4 Share Posted May 4 It's often mentioned that cosmic rays include non-charged subatomic particles like neutrons as part of their mix. This seems to contradict the two facts that an isolated neutron spontaneously decays within just 15 minutes and that the universe is awfully big. The only solution that springs to this mind is that extreme time dilation (due to near-lightspeed motion) hugely extends a neutron's normal existence, relatively speaking. Is this true? Or is this a classic instance of not seeing the elephant in the room? 🤥 Link to comment Share on other sites More sharing options...
exchemist Posted May 4 Share Posted May 4 (edited) 8 minutes ago, GeeKay said: It's often mentioned that cosmic rays include non-charged subatomic particles like neutrons as part of their mix. This seems to contradict the two facts that an isolated neutron spontaneously decays within just 15 minutes and that the universe is awfully big. The only solution that springs to this mind is that extreme time dilation (due to near-lightspeed motion) hugely extends a neutron's normal existence, relatively speaking. Is this true? Or is this a classic instance of not seeing the elephant in the room? 🤥 Are you sure this is right? My understanding was neutrons are some of the secondary products produced when cosmic rays interact with atoms in the atmosphere. Edited May 4 by exchemist Link to comment Share on other sites More sharing options...
Mordred Posted May 4 Share Posted May 4 1 hour ago, exchemist said: Are you sure this is right? My understanding was neutrons are some of the secondary products produced when cosmic rays interact with atoms in the atmosphere. That understanding is correct. 1 hour ago, GeeKay said: It's often mentioned that cosmic rays include non-charged subatomic particles like neutrons as part of their mix. This seems to contradict the two facts that an isolated neutron spontaneously decays within just 15 minutes and that the universe is awfully big. The only solution that springs to this mind is that extreme time dilation (due to near-lightspeed motion) hugely extends a neutron's normal existence, relatively speaking. Is this true? Or is this a classic instance of not seeing the elephant in the room? 🤥 The elephant your missing is that their are two categories (primarily) for cosmic rays. Primary and secondary. Primary cosmic rays are those sent from stellar objects like the Sun Secondary cosmic rays are those particles produced by the Primary rays interactions with our atmosphere. Neutrons are part of the secondary group. Part of that process includes mesons decays to that further allows leptons to form. Here is an examination of some of the different processes at different atmospheric levels https://pdg.lbl.gov/2019/reviews/rpp2019-rev-cosmic-rays.pdf Link to comment Share on other sites More sharing options...
pzkpfw Posted May 4 Share Posted May 4 Is the OP simply a mix-up of Neutron and Neutrino? Link to comment Share on other sites More sharing options...
exchemist Posted May 4 Share Posted May 4 24 minutes ago, pzkpfw said: Is the OP simply a mix-up of Neutron and Neutrino? Don't think the qualifier "standalone" would suggest the OP had neutrinos in mind. Link to comment Share on other sites More sharing options...
Mordred Posted May 4 Share Posted May 4 56 minutes ago, pzkpfw said: Is the OP simply a mix-up of Neutron and Neutrino? Doubtful he mentioned chargeless as well as the correct mean lifetime for an unbound neutron Link to comment Share on other sites More sharing options...
pzkpfw Posted May 4 Share Posted May 4 I read the OP as two parts: (paraphrased) A=heard that cosmic rays includes neutrons, B=stuff about neutrons that makes that hard to believe. While B included correct information about neutrons, it seemed possible the whole question might be a red herring if A was just that simple mix up. But I will back away slowly now. Link to comment Share on other sites More sharing options...
Mordred Posted May 5 Share Posted May 5 (edited) All 1 hour ago, pzkpfw said: I read the OP as two parts: (paraphrased) A=heard that cosmic rays includes neutrons, B=stuff about neutrons that makes that hard to believe. While B included correct information about neutrons, it seemed possible the whole question might be a red herring if A was just that simple mix up. But I will back away slowly now. All good Found a decent article for the OP though older describes the proton-neutron ratios of exchange in our atmosphere due to cosmic ray interaction. " At sea level, neutrons contribute about 10 percent of the total radiation exposure to man from cosmic rays (ref. 1). Neutrons reaching the Earth's surface are principally created in the Earth's atmosphere by the interaction of the primary cosmic rays with oxygen and nitrogen nuclei at high altitudes and in the subsequent development of a hadronic cascade down through the atmosphere. (Relatively few neutrons are present in the primary galactic cosmic radiation or solar radiation reaching the Earth because their radioactive half-life is approximately 12 min.) Two nuclear reactions are important in the production of cosmic-ray neutrons: direct inelastic reactions producing "knock-on" neutrons, with energies from about 1 MeV to well in excess of 1 GeV, and evaporation " https://ntrs.nasa.gov/api/citations/19760008919/downloads/19760008919.pdf Edited May 5 by Mordred 1 Link to comment Share on other sites More sharing options...
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