JAEA-Conf 2011-002 - 日本原子力研究開発機構

JAEA-Conf 2011-002
Yosuke IWAMOTO 1 , Koji NIITA 2 , Tomotsugu SAWAI 1 ,
R.M. RONNINGEN 3 , Thomas BAUMANN 3
1
Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 Japan
2
Research Organization for Information Science and Technology, Tokai-mura, Naka-gun, Ibaraki-ken
319-1195 Japan
3
National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824
U.S.A.
e-mail: iwamoto.yosuke@jaea.go.jp
Radiation damage in solids caused by various particles in wide range of energy is measured in a
common unit, DPA (Displacement per Atom). The DPA model in the Particle and Heavy Ion Transport code
System (PHITS) has recently been developed using Coulomb scattering to evaluate the energy of target
PKA’s created by the projectile and the secondary from nuclear reactions. For the Coulomb scattering, a
universal one-parameter differential scattering cross section equation introduced by J. Lindhard et. al. is
employed. The number of displacements in a cascade damage caused by a PKA was evaluated by the NRT
model. We compared PHITS results for the 130 MeV/u 76 Ge and proton into W reactions with calculated
results of TRIM, which is widely used and cannot treat nuclear reactions. PHITS gives good agreements
with TRIM results for DPA values by PKA’s directly created by the projectile such as 76 Ge and proton. On
the other hands, for the proton incident reaction, PKA’s created by the secondary particles is more dominant
than PKA’s by the projectile in DPA calculations. Therefore, TRIM leads to sever underestimation where
projectile energy is high enough to create nuclear reactions. PHITS is more reliable code than TRIM for
DPA calculations, especially in the high-energy region and proton incidence.
As the power of proton and heavy-ion accelerators is increasing, the prediction of the structural
damage to materials under irradiation is essential. The average number of displaced atoms per atom of a
material DPA serves as its quantitative measure: DPA=t where is the radiation damage cross section;
and t is the irradiation fluence, i.e., the product of the ion beam density and the bombardment time. The
level of the radiation damage in DPA units is used, for example, to estimate radiation damage of the target
and magnet material for heavy-ion and proton incident reactions in Rare Isotope Beam Facility (FRIB) [1]
and J-PARC facility [2]. Since Particle and Heavy Ion Transport code System (PHITS) [3] was used for the