Cosmic ray muons

Takagi, J., Hampel, W., Kirsten, T. (1974) Cosmic-ray muon-induced 129I in tellurium ores. Earth Planet. Sci. Lett., 24, 141-50. 

Firstly, the calibration of the individual chambers has been verified with muon runs. The charge yield obtained agrees well with the cosmic-ray muon calibrations performed several years ago. This is an indication for the longterm signal stability of these detectors. 

The nucleons consist mainly of photons, electrons, and positrons, and compose about 10 percent of the cosmic radiation at sea level. A fraction of muons and nucleons are absorbed while traversing the atmosphere. Variations in absorber thickness (air mass) are proportional to variations in barometric pressure. The absorption length for cosmic-ray muons at sea level in the atmosphere is 4,000 g/cm (Cocconl, 1951), and for cosmic nucleons, 120 g/cm (Hayakawa, 1969). Thus, it is clear that muons have significantly higher penetrating power than nucleons, about 33 times in the air. The probability of absorption rapidly increases with the atomic number, Z. In terms of lead shielding, these muons can penetrate a meter or more, while nucleons can be stopped in several inches of lead. 

This fact, with others mentioned in section C, support the argument that the major background is caused by the interaction of cosmic rays with the photomultiplier tubes, resulting in crosstalk between the two tubes. The small background reduction observed with an additional layer of shielding is due to high penetration of the cosmic-ray muon component, which requires massive lead shielding to remove. 

CMS Collaboration, Commissioning and performance of the CMS pixel tracker with cosmic ray muons. JINST 5, T03007 (2010)... 

Table 4.4 shows the yields for the masked and unmasked photomultiplier for both the Ru (3 source and for cosmic ray muons, as well as the HAPD result with the (3 source cosmic ray test of the HAPD is underway. As expected, the HAPD result with the [3 source correlates well with the result using the masked photomultiplier. 

Anderson s particle, which is now called the muon after the Greek letter mu, was actually a kind of heavy electron. It had a large mass, but it otherwise exhibited electronlike properties. This was a great puzzle to the physicists of the day, because there seemed to be no reason it should exist. It was not a component of ordinary matter. It could be observed in the high-energy cosmic ray laboratory, but it quickly decayed (that is, disintegrated) into other particles. 

The English physicist Cedi Powell discovered Yukawa s meson in 1947. Powell found evidence of its existence in photographic plates that had been exposed to cosmic rays in the Bolivian Andes. The particle was found to be a little heavier than the muon, and it interacted strongly with nuclei, as Yukawa s particle was expected to do. Unlike the muon, which always carried a negative charge, the new particle could have either a positive or a negative charge, or it could be electrically neutral. 

Fiber optic data cable will stretch from the shore for 30 km to a connector box some 4800 meters below the ocean surface. Strings of nine separate cables will rise vertically about 280 meters above the ocean floor. Each cable, held up by a float, will contain 24 detectors. The apparatus, referred to as a neutrino telescope, will have to pick up at least ten muon events per year from any given 1° patch of sky for the DUMAND scientists to be confident that they have a significant neutrino source, not just a few background pulses from non-ncutrino cosmic rays,... 

One application of these equations in nuclear chemistry involves the decay of rapidly moving particles. The muon, a heavy electron, has a lifetime, t, at rest, of 2.2 p,s. When the particle has a kinetic energy of 100 GeV (as found in cosmic rays), we observe a lifetime of yT or about 103t. (This phenomenon is called time dilation and explains why such muons can reach the surface of Earth.)... 

The picture, however, had changed rapidly after the end of the Second World War. The experiment of Conversi, Pancini, and Piccioni59 had shown that this particle had an interaction with nuclei much weaker than that expected for the Yukawa mediator. At the beginning of October of the same year 1947, Lattes, Occhialini, and Powell60 in Bristol had discovered in cosmic rays a new particle, that they called ir-meson. It is unstable and decays, with a mean life of 10-8 sec, into a neutrino and the particle of Anderson and Neddermeyer that was called p-meson or muon. 

Production rates increase with elevation of a target because cosmic rays at higher elevations have traveled through less mass in the atmosphere. Several methods for scaling production with elevation have been developed (e.g., Lai and Peters 1967 Lai 1991 Dunai 2000 Stone 2000). In the simplest case, changes in production of a nuclide with elevation can be approximated by an exponential function that mimics the exponential pattern of secondary cosmic ray flux for both neutrons and muons (Gosse and Phillips 2001) ... 

There are three principal types of nuclear reactions due to the interactions of terrestrial materials with cosmic rays (i) by high-energy spallation of nucleons (E > 40MeV), principally by neutrons, (ii) by thermal neutron capture, and (iii) muon-induced nuclear disintegrations. Muon reactions become important only at depths below sea level. The estimation of the production ratio is difficult because of lack of knowledge of the probabilities of formation of nuclides in the different reactions. 

Neutrino oscillations have up to now been detected in two systems. Atmospheric muon neutrinos, which originate from the collision of cosmic rays... 

Figure 5 Mean logarithmic mass of cosmic rays reconstructed from a) experiments measuring electrons, muons, and hadrons at...

This situation changed in 1937 when a new particle was discovered in a cosmic-ray experiment. It had the correct mass, and Yukawa s theory was thought to be vindicated as a consequence. However, the details of the theory did not correspond with the measured properties of this particle. In a confusing cosmic coincidence, it turned out that particle was a muon (a heavier electronlike particle), and it was not until 1947 that the pion (as the force carrier came to be known) was discovered. Finally, all the pieces of the the-... 

The sea level cosmic ray dose is 300 millirad-yr and the sea level ionization is 2.2 x 10 ion pairs m s l The sea level flux has a soft component, which can be absorbed in about 100 mm of lead (about 100 g-cm of absorber) and a more penetrating (largely muon) hard component. The sea level radiation is Icirgely produced in the atmosphere and is a secondary component from interactions of the primary particles. The steep primary energy spectrum means that most secondaries at sea level are from rather low energy primaries. Thus the secondary flux is dependent on the solar cycle and the geomagnetic latitude of the observer. 

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