Neutron Production by μ Mesons Which Penetrate Lead
1957; American Institute of Physics; Volume: 106; Issue: 5 Linguagem: Inglês
10.1103/physrev.106.1043
ISSN1536-6065
AutoresB. F. Stearns, D. R. Jones, J. K. dePagter, R. D. Sard,
Tópico(s)Chemical Synthesis and Characterization
ResumoThe mean product of cross section and multiplicity ($〈\ensuremath{\sigma}m〉$) for evaporation neutrons produced when fast cosmic-ray $\ensuremath{\mu}$ mesons traverse a Pb producer has been measured. A magnet cloud chamber above the producer and a hodoscope-absorber array below it serve to identify $\ensuremath{\mu}$ mesons; neutron-producing events are selected by the detection of a delayed coincidence of a thermalized neutron with a penetrating particle. $〈\ensuremath{\sigma}m〉=(22\ifmmode\pm\else\textpm\fi{}8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}29}$ ${\mathrm{cm}}^{2}$/nucleon. Theoretical calculations based on experimental photoneutron yields give $〈\ensuremath{\sigma}m〉=15\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}29}$ ${\mathrm{cm}}^{2}$/nucleon for the yield due to knock-on showers, and $〈\ensuremath{\sigma}m〉=9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}29}$ ${\mathrm{cm}}^{2}$/nucleon for the direct yield from equivalent photons of the $\ensuremath{\mu}$-meson field. This theory also agrees with the results of underground measurements at higher average momenta. There is no evidence of $\ensuremath{\mu}$-meson scattering in excess of Coulomb scattering. Protons which suffer nuclear interactions produce more than 50 neutrons, but seldom produce penetrating secondaries.
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