26. passage of particles through matter - Particle Data Group
26. passage of particles through matter - Particle Data Group
26. passage of particles through matter - Particle Data Group
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18 <strong>26.</strong> Passage <strong>of</strong> <strong>particles</strong> <strong>through</strong> <strong>matter</strong><br />
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(a) Carbon (Z = 6)<br />
− experimental σ tot<br />
Cross section (barns/atom)<br />
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1 b<br />
σ p.e.<br />
σ Rayleigh<br />
κ nuc<br />
10 mb<br />
σ Compton<br />
κ e<br />
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σ p.e.<br />
(b) Lead (Z = 82)<br />
− experimental σ tot<br />
Cross section (barns/atom)<br />
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σ Rayleigh<br />
κ nuc<br />
1 b<br />
σ Compton<br />
κ e<br />
10 mb<br />
10 eV 1 keV 1 MeV 1 GeV 100 GeV<br />
Photon Energy<br />
Figure <strong>26.</strong>13: Photon total cross sections as a function <strong>of</strong> energy in carbon and<br />
lead, showing the contributions <strong>of</strong> different processes:<br />
σ p.e. = Atomic photoelectric effect (electron ejection, photon absorption)<br />
σ Rayleigh = Coherent scattering (Rayleigh scattering—atom neither ionized nor<br />
excited)<br />
σ Compton = Incoherent scattering (Compton scattering <strong>of</strong>f an electron)<br />
κ nuc = Pair production, nuclear field<br />
κ e = Pair production, electron field<br />
<strong>Data</strong> from Hubbell, Gimm, and Øverbø, J. Phys. Chem. Ref. <strong>Data</strong> 9, 1023 (1980).<br />
Curves for these and other elements, compounds, and mixtures may be obtained<br />
from<br />
http://physics.nist.gov/PhysRef<strong>Data</strong>. The photon total cross section is<br />
approximately flat for at least two decades beyond the energy range shown. Original<br />
figures courtesy J.H. Hubbell (NIST).<br />
June 18, 2002 13:57
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