by the incident particle is shared among all degrees of freedom of the nucleus. The
reaction cross section from an initial channel α to a final channel β proceeding
through a compound nucleus state of spin J can be written by the Hauser–Feshbach
formula as
σ
cn
αβ ¼
π
k
2
α
X
J
g J
T α T β
X
γ
T γ
,
ð1:2Þ
where k α is the wave number in the initial channel, g J is a statistical factor, T is a
transmission coefficient, and hTi is the energy average of T. The statistical factor is
g J ¼
2J þ 1
2i α þ 1
ð
Þ2I α þ 1
ð
Þ
,
ð1:3Þ
where i α and I α are the projectile and target spins.
Calculations of reaction cross sections are performed using the nuclear model
code TALYS (version 1.4) [6]. The neutron transmission coefficients are calculated
via the global optical potential [7]. The gamma-ray transmission coefficients are
calculated through the energy-dependent gamma-ray strength function according to
Brink [8] and Axel [9]. We employed the level density given by Gilbert and
Cameron [10].
Figure 1.2 shows the photonuclear reaction cross sections of
137 Cs calculated
using the TALYS code. In the incident photon energy B(n) E γ < B(2n), where B
(n) and B(2n) are the one- and two-neutron binding energies, respectively, we can
see that the (γ, n) reaction mainly occurs. Because the resonance energy of GDR E R
is 15–18 MeV, which is roughly equal to B(2n) for medium nuclides, about half the
reactions via GDR are (γ, n) reactions, which occur at B(n) E γ < B(2n).
1.2.2 High-Energy Photons Obtained by Laser Compton
Scattering
Laser Compton scattering is a method to obtain high-energy photons by laser
photons backscattered off energetic GeV electrons. In the case of head-on collision
Giant Dipole Resonance : GDR
(collective excitation)
photon (~10MeV)
target
n
A
A–1
Z
Z
X
X
(g,n) reaction
Fig. 1.1 Schematic
illustration of nuclear
transmutation with laser
Compton scattering
1 Nuclear Transmutation of Long-Lived Nuclides with Laser Compton Scattering. . .
5
reaction cross section from an initial channel α to a final channel β proceeding
through a compound nucleus state of spin J can be written by the Hauser–Feshbach
formula as
σ
cn
αβ ¼
π
k
2
α
X
J
g J
T α T β
X
γ
T γ
,
ð1:2Þ
where k α is the wave number in the initial channel, g J is a statistical factor, T is a
transmission coefficient, and hTi is the energy average of T. The statistical factor is
g J ¼
2J þ 1
2i α þ 1
ð
Þ2I α þ 1
ð
Þ
,
ð1:3Þ
where i α and I α are the projectile and target spins.
Calculations of reaction cross sections are performed using the nuclear model
code TALYS (version 1.4) [6]. The neutron transmission coefficients are calculated
via the global optical potential [7]. The gamma-ray transmission coefficients are
calculated through the energy-dependent gamma-ray strength function according to
Brink [8] and Axel [9]. We employed the level density given by Gilbert and
Cameron [10].
Figure 1.2 shows the photonuclear reaction cross sections of
137 Cs calculated
using the TALYS code. In the incident photon energy B(n) E γ < B(2n), where B
(n) and B(2n) are the one- and two-neutron binding energies, respectively, we can
see that the (γ, n) reaction mainly occurs. Because the resonance energy of GDR E R
is 15–18 MeV, which is roughly equal to B(2n) for medium nuclides, about half the
reactions via GDR are (γ, n) reactions, which occur at B(n) E γ < B(2n).
1.2.2 High-Energy Photons Obtained by Laser Compton
Scattering
Laser Compton scattering is a method to obtain high-energy photons by laser
photons backscattered off energetic GeV electrons. In the case of head-on collision
Giant Dipole Resonance : GDR
(collective excitation)
photon (~10MeV)
target
n
A
A–1
Z
Z
X
X
(g,n) reaction
Fig. 1.1 Schematic
illustration of nuclear
transmutation with laser
Compton scattering
1 Nuclear Transmutation of Long-Lived Nuclides with Laser Compton Scattering. . .
5