Speaker
Toshiyuki Sumikama
(Tokyo University of Science)
Description
Low-energy nuclear reactions such as fusion-evaporation, multi-step Coulomb excitation, transfer reactions, etc. are important probes to investigate exotic structure of unstable nuclei. While RIBF provides world's most intense RI beams, an energy of about 250 MeV/A is much higher than required energies for low-energy reactions.
At the last NP-PAC meeting, we proposed the development of energy-degraded RI beams at RIBF. We will produce RI beams with 2–10 MeV/u at the final focal plane F11 of ZeroDegree spectrometer in order to perform gamma-ray spectroscopy. In this development beam time, we plan to use the 110Mo beam as a test case. In order to produce the required low energy RI beams, we will develop a momentum-bunched and achromatic RI beam, which is achieved by the combination of the momentum bunching degrader and new optics mode at the second stage of BigRIPS. With this new method, the beam energy will be pre-degraded from 250 MeV/u to 100 MeV/u, while the momentum spread will be reduced from 6% to 2.4% after the second stage. At the final focal plane, the beam energy is degraded by flat-plate degraders. The beam energy with 0–15 MeV/u and spot size of ~35 mm (FWHM) will be achieved. By considering the transmission and the requirement for energy range and beam spot size at F11, 41% of RI beams produced at F3 can be used for the low energy reactions.
In this workshop, I will show the proposed experiment to develop the energy-degraded RI beams.
Primary author
Toshiyuki Sumikama
(Tokyo University of Science)
