RI Beam Production at BigRIPS Since 2007 Kubo et al. Year Number of new isotopes Beam current (pnA) 0.007 pnA 0.3 0.22 10 6 12.6 238U beam New isotopes: 120 New isomers: 43 82 50 60 70 100 90 124Xe 70Zn 48Ca 18O Z N 28 20 8 238U In-flight fission Produced reactions: - In-flight fission of 238U - Projectile fragmentation of 14N, 18O, 48Ca, 70Zn, 124Xe Production Yield Measured (877) New isotope 2011 New isotope 2012, 2013 RI beam Produced (308) for 78 Experiments New isotope 2014 New isotope 2007, 2008 As of summer 2014

Challenge for the limit of existence Island of Stability Z=114, 120 N=184 r-process termination The 3rd peak of the r-process path Supernovae vs N-star mergers ? Neutron drip-line Projectile Fragmentation In-flight U fission & P.F.

RIBFのミッション → RIBF-upgradeのミッション 究極の原子核描像の確立 新奇ハロー核 新魔法数34 テトラ中性子核 魔法数の健在性 N=50, 82, 126? 新魔法数 N = 58、90、136？ 状態方程式 宇宙での元素合成過程 第二ピーク-レアアースまで 第三ピーク 　　超新星爆発 vs 中性子星合体？ 　　　　N=126原子核 　　　　中性子過剰Uの核分裂 RIビーム応用研究 核廃棄物核反応データ 　　核分裂生成物 核廃棄物核反応データ 　　MA

Neutron-orbit energies as a function of A 34 58 136 16 90 126 100 82 50 28 20 (14) 8 2 Hamamoto, Priv. Comm. Bohr & Mottelson, Nuclear Structure Vol.1 p239 (1969)

r-process path Puzzles R-process path Where is the site ?? Supernovae or Neutron-star Mergers or Both (mixed) Hot or cold ? (n,gamma) equilibrium or non-equilibrium Where is the r-process terminated ? fission decay in r-process path ? Magicity in heavy nuclei, N=184? R-process path Experimental Programs at RIBF Half Life : <- flow speed at EURICA Mass : <- path-way at Rare-RI Ring, MR-TOF Pn : <- n-source and decay-path at BRIKEN Fission-barrier height <- termination at SAMURAI

T1/2 for r-process path : A=100~130 Giuseppe, Nishimura et al., Phys. Rev. Lett. 114, 192501 (2015) T1/2 theoretically predicted T1/2 experimentally measured

Fission Systematic measurements for symmetric fission Heavy fragment in asymmetric fission 113-278 U-238 Systematic measurements for symmetric fission at high excitation energy? Excitation energy dependence Z/A distribution of fission fragments fissile nuclei heavier than U or MA

TRU-ISOL Nature 520, 209-U153 (2015) JAEA 68-MeV B-11 Beam + 185 micro-g/cm2 Cf target -> Lr-256 (27s) MA production with light stable and radioactive beams Post-acceleration for reaction study?

Challenge for the limit of existence Island of Stability Z=114, 120 N=184 Quasi-Fission Deep inelastic OEDO KISS Ge Fragmentation Fission Projectile Fragmentation In-flight U fission & P.F.

中間エネルギーのアクティビティを維持 しつつ、低エネルギーRIの核反応(融合反応, (多)核子移行反応)を基軸とした新しい研究展開 　　→　r過程第三ピーク 　 　　 安定の島 New Storage Ring Ultra Large Acceptance Spectrometer Active Target Low-E Beamline “Super BigBIPS” RI-GARIS SCRIT Multi-use capability Super RILAC + New FRC “HyperSRC” (future)

RIBF Initiatives :Pilot Programs at the present facility R&D for Production and Separation of heavy and n-rich nuclei Particle Identification Techniques RI+stable reactions Storage Ring? MA Acceleration Low-E Branch + Spectrometer + Ge detectors Post-accelerated RI ions TRU-ISOL? Reaction Study+ Collectivity Ca-52, 54 + Cm-248 The upgrade plan aiming at the completion in 2020 has been submitted to the Science Council of Japan in 2013. Although it was not listed in the top 27 proposals, we will improve the accelerator design and physics case.