Speaker
Dr
Yoshitomo Uwamino
(RIKEN Nishina Center for Accelerator-Based Science)
Description
RIKEN RIBF (Radioactive Isotope Beam Factory) is a big heavy-ion accelerator complex consists of a linac and five cyclotrons, of which last stage accelerator is a superconducting ring cyclotron (SRC). The maximum acceleration energy of it is 400 MeV/u for ions lighter than Ar and 350 MeV/u for heavier ions up to uranium. The accelerated beam is transported to BigRIPS (Big RIKEN Projectile-fragment Separator), which produces secondary RI beams.
To measure the secondary neutron field, activation samples of C, Al, Au and Bi were placed around BigRIPS, where the 345-MeV/u 238U86+ and 48Ca20+ beams were stopped. The maximum beam intensities were about 2x10^9 particle/s for uranium and 1x10^12 particle/s for calcium. The doses due to neutrons and photons were also measured with the thermoluminescence dosimeter (TLD). The thermal neutron sensitive TLD was inserted in a specially designed moderator of which sensitivity function had a similar shape of the dose equivalent conversion factor.
The activated samples were measured with Ge detectors, and the production of 12C(n,2na)7Be, 12C(n,2n)11C, 27Al(n,a)24Na, 27Al(n,2na)22Na, 197Au(n,g)198Au, 197Au(n,2n-4n)196Au-194Au, 209Bi(n,4n-10n)206Bi-200Bi were observed. The reaction rates spanned between 10^-33 and 10^-27 ([beam ion]^-1 [sample atom]^-1). The doses obtained with TLD spanned between 10^-21 and 10^-16 (Sv [beam ion]^-1). These results were compared with the calculations of the Phits heavy-ion Monte Carlo transport code.
Primary author
Dr
Yoshitomo Uwamino
(RIKEN Nishina Center for Accelerator-Based Science)
Co-authors
Mrs
Atsuko Akashio
(RIKEN Nishina Center for Accelerator-Based Science)
Dr
Atsushi Yoshida
(RIKEN Nishina Center for Accelerator-Based Science)
Mr
Hiroki Mukai
(RIKEN Nishina Center for Accelerator-Based Science)
Mr
Hiroyuki Fukuda
(RIKEN Nishina Center for Accelerator-Based Science)
Mr
Hisao Sakamoto
(RIKEN Nishina Center for Accelerator-Based Science)
Dr
Koichi Yoshida
(RIKEN Nishina Center for Accelerator-Based Science)
Dr
Rieko Higurashi-Hirunuma
(RIKEN Nishina Center for Accelerator-Based Science)
