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19

The cross-section for neutrino interactions is energy dependent. For solar neutrinos at $\sim 0.4$ MeV, which would likely dominate any neutrinos likely to interact (the cosmic background neutrinos have way low energies) , the cross-sections are $\sigma \sim 10^{-48}$ m$^2$, for both leptonic processes (elastic scattering from electrons) and ...


14

Great question. The electric field creates such a strong force that it would be very hard to move large amounts of just one type of charge. So astrophysical systems do generally eject equal numbers of protons and electrons. In particular, the solar wind is electrically neutral. So these cosmic rays are created in very nearly equal numbers, but by the ...


9

The short answer is you can't, or at least not at all easily. Your detector has only a single detection plane, and almost all muons are minimum ionizing, so you get essentially the same energy deposition from every muon (well, there is a factor from the angle of incidence the detection plane). The usual mechanism for measuring the energy of a particle are ...


9

The OMG particle was observed by the Fly's Eye experiment located on Dugway Proving Ground in Utah. The Fly's Eye experiment was the first experiment to successfully employ the air fluorescence technique developed by Dr. Alan Bunner (Cosmic Ray Detection by Atmospheric Fluorescence, Ph. D. Thesis, Cornell University, 1967). The air fluorescence technique ...


8

Ultra-high energy cosmic rays all come from a very, very long way away (anything with the power to create them nearby would constitute a danger to life as we know it). I think the preferred mechanism these days is dynamic acceleration in the jets formed by active galactic nuclei, but don't quote me. Anyway, ultra-relativistic though they are, that means ...


7

The short answer is "we do" (see Pierre Auger Observatory and others1), but it's not like you can build a CMS equivalent at the one spot in the whole atmosphere where a $10^{19}\text{ eV}$ cosmic ray is going to hit next year, so we do a different kind of particle physics there. A typical ultra-high energy cosmic ray observatory combines an array of ...


7

OK, here is something concrete and quantitative, "Guidelines for predicting single-event upsets in neutron environments": Neutrons in the atmosphere result from cosmic-ray spallation interactions with nitrogen and oxygen nuclei. A typical reaction is a 1 GeV proton fragmenting a nitrogen necleus into lighter charged particles and simultaneoously emitting ...


7

Ultra-high energy cosmic rays create enormous cascades of charged particles as they and interact and re-interact and re-re-interact in the atmosphere. This generates a lot of Cerenkov radiation and nitrogen fluorescence in the atmosphere and many of the charged particles reach the ground in a cone that may be miles wide. So you build an array of ground ...


6

We can make a reasonable guess by taking a look at the Hillas criterion. The gist of this criterion is that the maximum energy of the particle, $E$, is limited by the size of the accelerator, $R$ ($\sim R_L$ the Larmor radius), and the strength of the magnetic field, $B$. The relation gives $$ E_{max}=10^{18}\,Z\beta B_{\mu G}R_{kpc}\,{\rm eV} $$ where ...


6

Happens all the time. Low background neutrino detectors have to contend with the products: short lived, light isotopes that are created in after cosmic rays knock some neutrons loose from other material (neutron spallation). See (to chose an example I'm an author on) DOI 10.1103/PhysRevC.81.025807 (also at arXiv:0907.0066). You can also find simlar papers ...


6

If you are that fast in detecting light, you are seeing cosmic ray muons. They are charged and leave an ionizing track in anything they cross and Cerenkov light. in liquid, and the eye is mainly liquid. They are the most numerous energetic particles arriving at sea level, with a flux of about 1 muon per square centimeter per minute. This can be ...


6

It isn't needed in a rocket, however if you are going to the effort of sending something up outside the atmosphere (or even just high up within the atmosphere) you might as well try and get some useful data out of it. This might even help you get sponsorship for your rocket, as data from climbs through altitude is useful to a number of academic institutions. ...


5

Energetic cosmic rays are rare, as @John Rennie states in his answer, and the detectors to measure their effect cover kilometers. One high energy entrant creates what is called an air shower and it is measured as @dmckee describes. It is not possible to use them as an incoming beam because we do not know what they are ( except in the case of gamma rays and ...


5

Between what I've learned about cosmic rays and what I can find online (example: http://www.fisica.unlp.edu.ar/~veiga/experiments.html), it seems that the primary source of neutrons in cosmic ray showers is the disintegration of the atomic nuclei that are struck by the cosmic ray or its decay products. As you may know, cosmic rays enter the atmosphere with ...


4

One must keep in mind also that it is the particle, not the shower that goes through the astronaut in dmckee's estimate above, where he treats the relativistic particle going through matter. The shower in your question which gave the energy estimate of the parent particle is generated by cascade/sequential collisions of deep angle scattering over a ...


4

Roughly yes. Radiation is broadly divided into two from a safety point of view. Ionising radiation can break chemical bonds and so has an obvious way to cause damage to your body - how much depends on the energy, how much radiation you absorb and where in your body it gets to. Both X-Rays and particles from radioactive material are ionising, as is the ...


4

There is the ground based observatory ( nice picture) Veritas. VERITAS (Very Energetic Radiation Imaging Telescope Array System) is a major ground-based gamma-ray observatory located at the basecamp of the Fred Lawrence Whipple Observatory in southern Arizona, designed to observe and study very-high-energy (VHE) gamma-rays (energies above ~100 GeV). ...


4

The density is far too low, you can't predict where they will arrive and when, and you don't know the incoming energy. Apart from that they would be perfect :-)


4

Muon catalyzed fusion needs the muons to be low enough energy to replace an electron and stay in a stable orbit. Since the reason the catalysis happens is because the atom is much smaller and two protons can get close together enhancing the probability of overlap and fusion, one needs a large number of low energy muons so that the probability of two muonic ...


4

I'm a bit outside of my expertise here, and perhaps someone who knows in detail will be along, but here goes... The composition of UHE cosmic rays is not directly measured because they are too rare to justify putting a spectrometer sufficient to test them in space. The composition of normal cosmic rays has been tested and they are mostly protons with a few ...


4

One major problem with this proposal is that the cosmic ray hits a particle at rest, not another cosmic ray with the same energy going in the opposite direction. Under these conditions, if a cosmic ray proton at enormous energy E hits a proton at rest with mass m, the center of mass collision energy is found by boosting to the rest frame, and the result is a ...


4

To address the actual question of how we know the composition of UHECR without relying on source information (of which we have none), we have to look at their extensive air showers (EAS). After an UHECR hits the top of the atmosphere an EAS is created in the air, but p and Fe will create EAS with different shapes. Properties of hadronic interactions are ...


3

The Earth and the Sun has magnetic fields which shields us from cosmic rays, as a charged cosmic ray particle will loose kinetic energy when its direction is perpendicular to the magnetic field. So what happens to the kinetic energy of the cosmic ray particle? According to the first law of thermodynamics it can't just disappear. It goes to the magnetic ...


3

You are assuming the Big Bang happened at a point, so the CMB is a shell of radiation expanding outwards from that point. However the Big Bang happened everywhere so every point in the universe is a source of the CMB. The CMB radiation we are detecting today comes from regions of the universe that were about 13.8 billion light years away at the moment the ...


3

The general consensus is that the knee represents the transition from galactic sources (supernova remnants) and extra-galactic sources (AGN, blazars, etc). At about $10^{15}$ eV, the gyroradius of a proton is $$ r\sim3\frac{\left(mc^2/GeV\right)\left(v/c\right)}{\left(|q|/e\right)\left(B/T\right)}\simeq10^{16}\,{\rm m} $$ where we assume a background ...


3

Yes, they're thermalized and captured. Remember that the free neutron lifetime is roughly fifteen minutes, and that thermal neutrons are moving a couple kilometers per second. The chance of going fifteen minutes without a capture interaction is tiny. (Even in so-called "neutron bottle traps," it's hard to get the mean time before neutron disappearance to ...


3

It is more likely that the non-detection would be associated with statistics than SNR's not accelerating protons. Fermi-LAT has already shown that $\gamma$-ray emissions from 4 galactic supernova remnants (with molecular clouds nearby them) are coming from proton-proton collisions leading to neutral pions ($pp\to pp\pi^0$, $\pi^0\to2\gamma$): (source, ...


3

because this is the most probable configuration. Black-body light is the thermal equilibrium for light, so that anything that produces light which has a finite energy produces light that knocks around eventually to become blackbody light. The light we see was scrambled during the first 300,000 years by innumerable collisions with electrons and nuclei, and ...


3

2012-07-11 Addendum Based on excellent inputs, in particular from @annav, my answer is now "no, even a direct worst-case hit by the Oh-My-God particle would not kill you, even by radiation, because there is insufficient distance and angle to generate a fatal radiation cone. Thanks all, and be sure to look at the earlier answer that @dmckee pointed out. ** ...


3

For the most part cosmic rays do nothing to consumer electronics. This is not to say that they can't flip bits or even damage elements, but the rate for such effects is very, very low. Radiation effects are routinely observed in electronics placed in accelerator experimental halls (where the radiation levels are at lethal-dose-in-minutes levels when the ...



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