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Is this something that reasonable people should try to protect themselves from? I spend most of my time indoors. Will my house's roof protect me, or is this the

by Pyxl101 10y ago

Is this something that reasonable people should try to protect themselves from? I spend most of my time indoors. Will my house's roof protect me, or is this the kind of ray that penetrates everything? Is there some simple insulation one could install to mitigate the risk? Specifically around one's sleeping quarters, where disproportionate time is spent. Do cosmic rays disproportionately come from one direction? I realized that I'm somehow thinking of them coming down from straight up. However, they could come in at any angle I suppose, or even upwards through the earth if they're capable of passing through it. That being said, if atmosphere or matter degrade or deter cosmic rays, then I imagine they probabilistically come from straight up, since that requires passing through the least atmosphere.

cshimmin 10y ago
Not much you can do to shield these events, it's mostly highly-penetrating gamma rays and muons. Maybe spend a lot of time a few dozen meters underground or the the basement of high-rise buildings. If it helps, you basically have to be within a meter of these things to really experience significant radiation (rough estimate; I don't know what dose actually corresponds to cancer). At a rate of 1/km^2/yr, that means the odds of one of these hitting within 1m of you in a year is 3e-6. In other words, you can expect to get hit once about every 320,000 years. So I wouldn't worry about it personally. However it's interesting to note that the same logic implies that about 22,000 people are affected globally each year. As for directionality, they can come from pretty much any direction, but as the angle deviates from zenith (straight up), the particles have to travel through more atmosphere, so the intensity is decreased. Neutrinos can travel upwards through the earth, but you don't have to worry about those causing health problems (for the same reason they are able to pass right through the earth).
- batbomb 10y ago
  yeah I was referring to the specific case where the observer is roughly close to x_max for a 10^19 or above event and quite literally in the ionization column. You can get rid of almost all of the electronic and gamma components in with about 10 feet sand, 5 feet concrete or 1 foot of lead, but that of course doesn't stop the muonic component. (I worked on HiRes/Telescope Array for 4 years on muon detectors and bi-static radar techniques for UHECRs, but that was quite a while ago and some of my memory might be slightly off) Not sure how much energy would be deposited, but I'm sure it's not insignificant. It's rare enough that no one person could expect it to happen but probably frequent enough that it does happen at least once a decade in a densely populated area.

by Pyxl101 10y ago

cshimmin 10y ago

Not much you can do to shield these events, it's mostly highly-penetrating gamma rays and muons. Maybe spend a lot of time a few dozen meters underground or the the basement of high-rise buildings. If it helps, you basically have to be within a meter of these things to really experience significant radiation (rough estimate; I don't know what dose actually corresponds to cancer). At a rate of 1/km^2/yr, that means the odds of one of these hitting within 1m of you in a year is 3e-6. In other words, you can expect to get hit once about every 320,000 years. So I wouldn't worry about it personally. However it's interesting to note that the same logic implies that about 22,000 people are affected globally each year. As for directionality, they can come from pretty much any direction, but as the angle deviates from zenith (straight up), the particles have to travel through more atmosphere, so the intensity is decreased. Neutrinos can travel upwards through the earth, but you don't have to worry about those causing health problems (for the same reason they are able to pass right through the earth).

batbomb 10y ago
yeah I was referring to the specific case where the observer is roughly close to x_max for a 10^19 or above event and quite literally in the ionization column. You can get rid of almost all of the electronic and gamma components in with about 10 feet sand, 5 feet concrete or 1 foot of lead, but that of course doesn't stop the muonic component. (I worked on HiRes/Telescope Array for 4 years on muon detectors and bi-static radar techniques for UHECRs, but that was quite a while ago and some of my memory might be slightly off) Not sure how much energy would be deposited, but I'm sure it's not insignificant. It's rare enough that no one person could expect it to happen but probably frequent enough that it does happen at least once a decade in a densely populated area.