Study of the Interaction of Charged Ions with Matter - Development of Charge stripper and IF production Target at RISP

Abstract

In this thesis paper, we had studied on three different topics which are charged ion interaction with matter, liquid lithium charge stripper and IF production target. In RAON accelerator, prediction of charge state distribution of the uranium primary beam with 18 MeV/u energy and 33+ charge state after passing through liquid lithium film is one of the important issue. Estimation of thickness of film thickenss is also required to reach wanted averaged charge state of 79+. Since the charge state distribution of the uranium beam at the stripper energy of 18 MeV/u from a lithium film is not experimentally known, simulation methods are being developed. The simulation method is based on the further development of the ETACHA code in collaboration with the ETACHA group at the Institut des NanoSciences de Paris. In previous ETACHA4, number of shell was considered up to n=4, 60 electrons. ETACHA4E(extended version of ETACHA4) optimized with experimental data is improved to consider up to n=7. The excitation cross section is also rescaled with considering contribution of n=8 shell. We modified ETACHA4 and obtained the accuracy of the averaged charge state less than 1 % compared with experimental data in the energy region of ∼ 10 MeV/u. At the RAON energy, the thickness of lithium film is to be 1mg/cm2 to reach the 79+ of charge state for uranium beam. In this thesis paper, we had studied on three different topics which are charged ion interaction with matter, liquid lithium charge stripper and IF production target. In RAON accelerator, prediction of charge state distribution of the uranium primary beam with 18 MeV/u energy and 33+ charge state after passing through liquid lithium film is one of the important issue. Estimation of thickness of film thickenss is also required to reach wanted averaged charge state of 79+. Since the charge state distribution of the uranium beam at the stripper energy of 18 MeV/u from a lithium film is not experimentally known, simulation methods are being developed. The simulation method is based on the further development of the ETACHA code in collaboration with the ETACHA group at the Institut des NanoSciences de Paris. In previous ETACHA4, number of shell was considered up to n=4, 60 electrons. ETACHA4E(extended version of ETACHA4) optimized with experimental data is improved to consider up to n=7. The excitation cross section is also rescaled with considering contribution of n=8 shell. We modified ETACHA4 and obtained the accuracy of the averaged charge state less than 1 % compared with experimental data in the energy region of ∼ 10 MeV/u. At the RAON energy, the thickness of lithium film is to be 1mg/cm2 to reach the 79+ of charge state for uranium beam. at 50m/s bombarded by a 65 keV, 300W proton beam was successfully tested at ANL to test the validation of lithium film as as charge stripper. Study on the production target of in-flight fragment separator has been performed for a high power rare isotope facility planned in Korea. The maximum power of the primary beam is designed to be 400 kW, and the heat deposit on the target can reach a hundred kW. We consider a graphite multislice rotating system to maintain maximum target temperature below 1900 deg. Only radiation cooling is effective for this rotating target. Thickness of the target optimized for the maximum yield of 132Sn isotope is calculated to be 0.45g/cm2 and deposited heat is 132 kW. Target system should last at least a couple of weeks before exchange to a new unit for nuclear physics experiments. We have studied thermo-mechanical behavior assuming variations of thickness of graphite target from 0.1 to 1mm, and of the diameter from 13cm to 30cm. The results were simulated using PHITS, LISE++ and ANSYS. By using the simulation results, we built the 1st IF production target with the diameter of 140mm and thickness of 0.2mm and tested by 70 keV, 1kW electron beam at local company EBTech. The maximum temperature reached to 800 oC. And we are now preparing 2nd prototype IF production target with a the diameter of 140mm and thickness of 0.2mm. In near future 2nd prototype will be test with 1MeV, 100kW electron beam at BINP. We are expecting that the charge stripper and IF production target will be installed and operated for RAON accelerator based on these researches.