RADIATION INTERACTIONS
Charged Particles
Ionization, Excitation,
Bremsstrahlung
(
â
), Annihilation (
â
)
-
+
Neutrons
Scattering (E > 0.025 eV)
Elastic (energy and momentum are conserved)
Inelastic (photon emitted)
Absorption (E < 0.025 eV)
Radiative Capture (n,
ã
)
Particle Emission (n,
á
) (n, p) (n, n)
Fission (n, f)
Gamma or X-ray photons
Photoelectric Effect (generally < 1 MeV)
Compton Scattering (generally 200 keV - 5 MeV)
Pair Production (minimum 1.022 MeV)
Scattered Photon
0
2
T' = T / [1 + T(1 - cos
è
) / m c ]
where c = 931.5 MeV / amu
2
Bremsstrahlung
emitted energy is ~ 1/3 of the electron energy
x
0
Photon Attenuation:
I =
I e
µx
Interaction Probability per gram:
Photoelectric
%
Z / E
3
3
Compton independent of Z
Pair Production
%
Z
1
Total
pe
cs
cc
µ
=
µ
+
µ
+
µ
Air
W
=
33.9 eV per ion pair
Specific Ionization
=
S/W (i.p. / cm)
5
2
RADIATION INTERACTIONS
Charged Particles
Ionization, Excitation,
Bremsstrahlung
(
â
), Annihilation (
â
)
-
+
Neutrons
Scattering (E > 0.025 eV)
Elastic (energy and momentum are conserved)
Inelastic (photon emitted)
Absorption (E < 0.025 eV)
Radiative Capture (n,
ã
)
Particle Emission (n,
á
) (n, p) (n, n)
Fission (n, f)
Gamma or X-ray photons
Photoelectric Effect (generally < 1 MeV)
Compton Scattering (generally 200 keV - 5 MeV)
Pair Production (minimum 1.022 MeV)
Scattered Photon
0
2
T' = T / [1 + T(1 - cos
è
) / m c ]
where c = 931.5 MeV / amu
2
Bremsstrahlung
emitted energy is ~ 1/3 of the electron energy
x
0
Photon Attenuation:
I =
I e
µx
Interaction Probability per gram:
Photoelectric
%
Z / E
3
3
Compton independent of Z
Pair Production
%
Z
1
Total
pe
cs
cc
µ
=
µ
+
µ
+
µ
Air
W
=
33.9 eV per ion pair
Specific Ionization
=
S/W (i.p. / cm)
5
2
RADIATION INTERACTIONS
Charged Particles
Ionization, Excitation,
Bremsstrahlung
(
â
), Annihilation (
â
)
-
+
Neutrons
Scattering (E > 0.025 eV)
Elastic (energy and momentum are conserved)
Inelastic (photon emitted)
Absorption (E < 0.025 eV)
Radiative Capture (n,
ã
)
Particle Emission (n,
á
) (n, p) (n, n)
Fission (n, f)
Gamma or X-ray photons
Photoelectric Effect (generally < 1 MeV)
Compton Scattering (generally 200 keV - 5 MeV)
Pair Production (minimum 1.022 MeV)
Scattered Photon
0
2
T' = T / [1 + T(1 - cos
è
) / m c ]
where c = 931.5 MeV / amu
2
Bremsstrahlung
emitted energy is ~ 1/3 of the electron energy
x
0
Photon Attenuation:
I =
I e
µx
Interaction Probability per gram:
Photoelectric
%
Z / E
3
3
Compton independent of Z
Pair Production
%
Z
1
Total
pe
cs
cc
µ
=
µ
+
µ
+
µ
Air
W
=
33.9 eV per ion pair
Specific Ionization
=
S/W (i.p. / cm)
5
2
RADIATION INTERACTIONS
Charged Particles
Ionization, Excitation,
Bremsstrahlung
(
â
), Annihilation (
â
)
-
+
Neutrons
Scattering (E > 0.025 eV)
Elastic (energy and momentum are conserved)
Inelastic (photon emitted)
Absorption (E < 0.025 eV)
Radiative Capture (n,
ã
)
Particle Emission (n,
á
) (n, p) (n, n)
Fission (n, f)
Gamma or X-ray photons
Photoelectric Effect (generally < 1 MeV)
Compton Scattering (generally 200 keV - 5 MeV)
Pair Production (minimum 1.022 MeV)
Scattered Photon
0
2
T' = T / [1 + T(1 - cos
è
) / m c ]
where c = 931.5 MeV / amu
2
Bremsstrahlung
emitted energy is ~ 1/3 of the electron energy
x
0
Photon Attenuation:
I =
I e
µx
Interaction Probability per gram:
Photoelectric
%
Z / E
3
3
Compton independent of Z
Pair Production
%
Z
1
Total
pe
cs
cc
µ
=
µ
+
µ
+
µ
Air
W
=
33.9 eV per ion pair
Specific Ionization
=
S/W (i.p. / cm)
5
2
