Overview of the Rare Isotope Science Project of the Institute for Basic Science

New Physics: Sae Mulli, Vol. 66, No. 12, December 2016, pp. 1458∼1464 http://dx.doi.org/10.3938/NPSM.66.1458 Overview of the Rare Isotope Science Project of the Institute for Basic Science Sunchan Jeong∗ Rare Isotope Science Project, Institute for Basic Science, Daejeon 34047, Korea (Received 16 November 2016 : revised 13 December 2016 : accepted 13 December 2016) The Rare Isotope Science Project of Institute for Basic Science was launched in 2011 with the unprecedented aim of constructing a heavy-ion linear accelerator complex in Daejeon, Korea. The goal of the accelerator complex, named RAON, is to produce a variety of stable and rare isotope beams for studies in basic sciences and various other applications. Powered by a 400 kW superconducting linac, the facility is intended to establish In-flight Fragment and Isotope Separation On-Line facilities and to run those facilities simultaneously to become the most effective producer of rare isotope beams worldwide. The prototype construction of the major accelerator components is almost complete, and subsequent testing is ongoing. We briefly introduce the RAON accelerator and the experimental systems, together with RAON’s theoretical activities. The current status and the short-term prospects of the Rare Isotope Science Project are also presented. PACS numbers: 81.05.Ea, 85.30.Tv Keywords: Astrophysics, Condensed matter physics, Nuclear physics, Particle physics, Physics education I. INTRODUCTION ISOL (Isotope Separation On-Line) system and a post- accelerator also for the ISOL system. The ISOL and Under the International Science Business Belt (ISBB) the IF systems can be operated simultaneously and in- project by Korean Government, Institute for Basic Sci- dependently for most effective production of RI (rare iso- ence (IBS) was established in November 2011 to provide tope) beams in the world. In addition, the rare isotopes a creative research environment for basic science and produced in the ISOL can be injected into the Driver thereby to promote basic sciences in Korea. Just one Linac for accelerating the rare isotope beam (RIB) to month after IBS, Rare Isotope Science Project (RISP) even higher energies or for use in IF system to produce was launched with a challenging goal to construct a rare even more exotic rare isotopes. Therefore, RAON will isotope beam facility as a key research facility of IBS, certainly provide unique research opportunity worldwide called RAON. RISP is going to complete RAON by De- for nuclear physics and nuclear astrophysics as well as cember 2021 and its total budget is 1.44 billion USD including accelerator and experiment systems, civil en- applied fields such as bio- and medical-science, neutron gineering and conventional facilities. Out of 1.44 BUSD, science, and materials science. For a recent overview of 460 million USD was initially assigned for accelerator and RISP, we refer to [1]. experimental apparatus. The total budget including the budget for civil engineering and conventional facilities was approved in June 2014. II. RAON ACCELERATOR SYSTEMS RAON will be equipped with a heavy ion linear ac- The goal of the RAON accelerator complex is to pro- celerator as the driver for the IF (In-flight Fragmenta- tion) system, a proton cyclotron as the driver for the duce variety of stable and rare isotope beams to be used for researches in basic science and various appli- ∗E-mail: [email protected] cations. The RAON consists of three superconducting This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ≪ Review Article ≫ Overview of the Rare Isotope Science Project of the Institute for ··· – Sunchan Jeong 1459 Fig. 1. (Color online) Layout of RAON. is going to have both the Isotope Separation On-Line (ISOL) and In-Flight (IF) fragmentation methods to produce rare isotope beams far from the valley of stability. As summarized in Fig. 2 the two methods are comple- mentary. For the production of radioactive nuclei, the ISOL has a much greater advantage (about 104 times) than the in- flight method due to the target thicknesses and primary beam intensities available for production. For the in- Fig. 2. (Color online) Comparison of the two RIB pro- flight method, only an electromagnetic separator isnec- duction methods. essary. However, more factors are involved for the ISOL method including the efficiencies of extraction from the linacs of which superconducting cavities are indepen- target materials and ionization. dently phased and operating at three different frequen- To go one step further, RAON has a challenging plan cies. In order to meet the diverse demands on beam to combine the ISOL and IF system to produce the more species and energies, it can deliver various stable ions exotic RI beams with a greater intensity, namely 80% of from protons to uranium atoms and rare isotope beams all isotopes predicted to exist for elements below ura- with energies variable from the injector energy. For the nium. The ISOL system, probably with actinide tar- extensive discussion on RAON accelerator systems, we gets, is to be used to produce high-intensity beam of refer to [2]. neutron-rich isotopes of the easiest-to-extract elements (i.e., fast diffusion and effusion in the target materials), III. RAON RI PRODUCTION SYSTEMS and then the produced RIB is to be accelerated to an energy enough for projectile fragmentation. The in-flight The primary goal of RAON is to study unexplored technique for fast separation can be then applied to ob- territory of the nuclear landscapes. To this end, RAON tain beams of very neutron rich nuclei. 1460 New Physics: Sae Mulli, Vol. 66, No. 12, December 2016 Produced rare isotopes will be used for and will be studied at various experimental facilities of RAON. Now, we give a brief introduction of the ISOL and IF systems. For the extensive discussion on RAON RI production and experimental systems, we refer to [3]. 1. ISOL The ISOL technique has been mainly developed at CERN/ISOLDE in order to separate rare isotopes of interest from the produced target fragments. This type Fig. 3. (Color online) Science territory of RAON. of facility requires some additional complicated systems including an ISOL-system and an accelerator for radioac- acceptances and two-staged separation. The large accep- tive ions. High efficiencies are required at each stage of tances allow RI beams produced by projectile fragmen- production; ionization, separation, and transportation. tation as well as U-fission fragmentation method. The These developments are inter-related and thus many de- RAON IF uses an electromagnetic separator to separate velopments are still necessary. Especially, one has to and guide rare isotope beams to experimental halls for extract the rare isotope of interest from the bulk of the further studies. production target. The rate-determining steps are the The major technical challenges will be a high power diffusion and effusion of the rare isotope in the target production target, high power beam dump for removing materials, the rate of which depends on the combina- primary beam, a HTS (high temperature superconduct- tion of target material and element to be extracted, and ing) magnet in a hot cell region, and large aperture su- is often slow compared to the lifetime of the nuclide of perconducting magnet. The design of the IF system has interest. been completed and the prototyping of each component The ISOL system of RAON will be derived by a 70- is currently underway. MeV cyclotron that will induce fission on a direct fissile The rare isotope beams separated from the IF sepa- 14 target with a rate of 10 fissions/s. Short-lived neutron- rator will be delivered to the high energy experimental rich isotopes mostly with mass range 80 < A < 160 are facility; for instance, LAMPS to study exotic state of expected to be produced by fission in a hot (about 2000 nuclear matter and nuclear symmetry energy. ◦C) target. The fission-product beam isolated by ISOL will be post-accelerated by a superconducting linear accelerator SCL3 for low energy experiments. Recently, we IV. RAON EXPERIMENTAL SYSTEMS successfully extracted Sn-isotopes via a laser ionization and made a large LaCx target with 50 mm in diameter. The science programs of RAON include the study of exotic nuclei, hadrons in nuclei or in nuclear matter, equation of state of nuclear matter, origin of heavy ele- 2. IF ments, limits of nuclear existence, energy generation of stars, chemical history of the universe, compact stellar IF system is another main device to produce and sep- objects like neutron stars, etc. Though there may not be arate RI beams using 400 kW primary beams at RAON a great chance, together with supercomputers, RAON and is derived by a 400kW superconducting linear accel- might be able to contribute significantly to understand- erator system, where U beam could be accelerated up to ing nuclear physics in terms of its underlying theory such 200 MeV/u. The RAON IF separator is featured by large as QCD (quantum chromodynamics). ≪ Review Article ≫ Overview of the Rare Isotope Science Project of the Institute for ··· – Sunchan Jeong 1461 Fig. 4. (Color online) RAON experimental systems. Also, RAON is going to play important roles in applied energy and angular distribution, and the determi- sciences; some of such applications include finding new nation of nucleon occupancy in single particle or- materials, mutating cells or DNA, nuclear data evalua- bit (inelastic scattering, (d,p) reaction, nucleon re- tions, and development of new heavy ion cancer therapy moval reaction, etc). methods. p Study of soft dipole and Pygmy dipole resonances Fig.

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