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The lateral distribution of penetrating particles in cosmic ray extensive air showers. Technical Report No. 70

Technical Report ·
DOI:https://doi.org/10.2172/4229368· OSTI ID:4229368
The penetrating component of extensive air showers detected by the MIT air shower experiment at Harvard. Massachusetts, was observed with the aid of a large hodoscope shielded by 985 g/cm/sup 2/ of lead. The number of electrons, core location, and arrival direction of each shower were given by the air shower experiment. Mu-mesons associated with a shower could be identified by requiring the projected zenith single as measured by the hodoscope to agree with the known arrival direction of the shower. An auxiliary detector consisting of a single heavily shielded tray of counters was operated 920 m from the center or the array. In showers with zenith singles less than 25 deg the density of mu-mesons is proportional to r/sup -1.0 plus or minus 0.2/ for r between 20 and 150 m. (r is the distance from the shower core to the meson detector.) For r between 200 and 900 m the density is proportional to r/sup -2.2 plus or minus 0.1/. The shape of the lateral distribution changes as the zenith angle of the showers is increased. The nature of this change is such that the mesons is inclined showers are more spread out than those in vertical showers. The effect of the magnetic field of the earth on the lateral distribution is small. The meson density near the core is proportional to Ne/sup 0.79 plus or minus 0.05/ where Ne is the number of electrons in the shower. For showers with a constant observed number of electrons, the meson density near the core does not change with zenith angle. This fact implies that, in a shower of given primary energy, the density near the core decreases exponentially with depth with in absorption length of (253 plus or minus 40) g/cm/sup 2/. The fraction of the mu-mesons with ranges greater than 540 g/cm/sup 2/ of lead which are absorbed in an additional 360 g/cm/sup 2/ of lead is (9.9 plus or minus 1.5)%. This fraction is independent of distance to the core for r between 40 and 300 m. (auth)
Research Organization:
Massachusetts Inst. of Tech., Cambridge, MA (United States). Lab. for Nuclear Science
Sponsoring Organization:
US Atomic Energy Commission (AEC); National Science Foundation
NSA Number:
NSA-13-022607
OSTI ID:
4229368
Report Number(s):
AECU--4356
Country of Publication:
United States
Language:
English

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