Study of Heavyion Induced Fission for Heavy Element

Study of Heavy-ion Induced Fission for Heavy Element Synthesis Katsuhisa Nishio Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, JAPAN INPC 2013

Contents Motivation In-beam fission experiment at JAEA tandem facility Theoretical model Evaporation residue measurement Conclusions

Super-heavy Nuclei Heavier Element 48 Ca + Actinide Target Nuclei 120 (FLNR) Proton Number Cold Fusion (GSI, RIKEN) Pb, Bi Targets 162 Missing Region Spherical Shell 114 Using Radioactive Nuclei 108 184 Deformed Shell α sf EC β- Neutron Number Understanding for fusion using actinide target nuclei are important to explore SHN

Three steps for hｅａｖｙ-element synthesis 34 S 14 + 238 U 92 (1) Contact 272 Hs* 108 (2) Fusion. CN 6. 6× 1012 Quasifission 268 Hs 108 + 4 10 n (3) Evaporation 3. 0× 1011 Fusion. Fission 6. 3× 1012 Fusion probability 1 atom ~ 3× 1011

Orientation effects in fusion and quasi-fission 274 Hs (Z=108) Compund Nucleus 208 Pb 132 Sn Quasi-fission n o ati ng Neutron Fusion Elo 78 Ni 36 S 238 U Potential Energy Proton 238 U Potential by Y. Aritomo + 0 - s s Ma y ym s A tr e m

JAEA Tandem facility at Tokai 20 MV Tandem (20 UR) Super-conducting Booster Liniac ECR Ion Source on the terminal Negative Ion Source JAEA Tokai Campus

In-beam fission measurement 30 Si, 31 P, 36, 34 S, 40 Ar, 40, 48 Ca Beams 200 mm 120 mm Fission Fragment 1 Fission Fragment 2 Multi-Wire Proportional Counter 238 U MWPC 1 238 U target MWPC 2 5 mm

Fission cross section (mb) Orientation effects in 36 S + 238 U One-dimensional Model Deformation of 238 U K. Nishio et al. , Phys. Rev. C, 77 (2008) 064607. Quasifission

Fission fragment mass distributions Cross section to produce fragments (mb) High Incident Energy 238 U Fragment Mass Quasifission Excitation Energy of CN Low Incident Energy K. Nishio et al. , Phys. Rev. C, 77, 064607 (2008). K. Nishio et al. , Phys. Rev. C, 82, 044604 (2010).

Dynamical calculation of nuclear shape – Fluctuation dissipation model － Langevin Equation Potential Energy (Me. V) 272 Hs CN Fusion 238 U 34 S Quasifission Fission Two center shell model ( 3 dimension ) ter en e. C e arg nc Ch Dista try e m V. Zagreabev, J. Phys. G, 31, 825 (2005). m sy A Y. Aritomo et al. , Nucl. Phys. A 753, 152 (2005). ss a Y. Aritomo, Phys. Rev. C, 80, 064604 (2009). M

Shape evolution ( Polar collisions) 30 Si + 238 U Y. Aritomo et al. , Phys. Rev. C 85, 044614 (2012) CN 36 S + 238 U CN 0– 5 F Fis usi m si on =1 on 3 8 4 ias on 0 Qu si 20 Fism = ter en e. C arg ce Ch stan Di ry t s me s a M sym A Qu Fis a m si si=1 on 7 5 – 10 10 – 30 Time (× 10 -21 s ) 30 – 50 > 50

Fusion probability 30 Si Fusion Probability + 238 U 46 % Histogram All Fission Fragments Cross section (mb/2 u) 41 % 37 % 33 % 29 % 34 S + 238 U 15 % 263 Sg 11 % 264 Sg 4. 9 % 3. 6 % Fusion-Fission Experimental Data 267 Hs 7. 5 % Filled Area Mass c. m. Energy (Me. V) Mass 268 Hs

Measurement of evaporation residue cross sections at GSI-SHIP 30 Si + 238 U = 268 Sg* 30 Si 34 S Silicon strip detector beams (1. 0 pμA) in 2006 + 238 U = 272 Hs* 34 S beams (2. 0 – 2. 5 pμA) in 2009 Timing detector 238 U Targets SHIP S. Hofmann and G. Münzenberg, Rev. Mod. Phys. 72, 733 (2000).

Fusion and evaporation residue cross sections Evaporation Residue Cross section (mb) 34 S + 238 U Excitation E energy 10 pb 67 pb Energy in c. m. (Me. V) K. Nishio et al. , PRC 82, 044604 (2010). Capture Cross Section ×Fusion Probability Quasifission Fission cross section (mb) Qasifission Excitation energy Fusion Cross Section Evaporation Residue Cross section (mb) + 238 U Fission Cross section (mb) 30 Si ×Survival Probability (Statistical Model ) 0. 54 pb 1. 8 pb Cross sections for SHN Energy in c. m. (Me. V) K. Nishio et al. , PRC 82, 024611 (2010).

Fusion probabilities for 40, 48 Ca + 238 U Fusion Probability Q ( 40 Ca + 238 U ) = - 138. 6 Me. V Q ( 48 Ca + 238 U ) = - 159. 1 Me. V 282, 283 Cn Ec. m. K. Nishio et al. , Phys. Rev. C, 86, 034608 (2012)

Summary Orientation effects on fusion probability are observed Fusion probabilities determined by the in-beam fission experiment can explain evaporation residue cross sections for 30 Si, 34 S + 238 U Measurement of evaporation residue cross section at the deep sub-barrier energies is desired to draw comprehensive picture of orientation effects.

K. Nishio, H. Ikezoe, S. Mitsuoka, I. Nishinaka, H. Makii, Y. Wakabayashi, Y. Nagame Japan Atomic Energy Agency, Tokai, Japan A. Andreyev University of York, UK S. Hofmann, D. Ackermann, F. P. Heßberger, S. Heinz, J. Khuyagbaatar, B. Kindler, V. F. Comas J. A. Heredia, I. Kojouharov, B. Lommel, R. Mann, B. Sulignano, Ch. E. Düllmann, M. Schädel GSI, Darmstadt, Germany S. Chiba Tokyo Institute of Technology, Japan S. Antalic, S. Saro Comenius University, Bratislava, Slovakia A. G. Popeko, A. V. Yeremin, A. Svirikhin Flerov Laboratory of Nuclear Reactions, Dubna, Russia A. Yakushev, A. Gorshkov, R. Graeger, A. Türler Technical University Munchen, Garching, Germany P. Kuusiniemi University of Oulu, Pyhayarvi, Finland T. Ohtsuki, K. Hirose Institute for Nuclear Physics, Tohoku University, Sendai, Japan Y. Watanabe High Energy Accelerator Research Organization, Tsukuba, Japan Y. Aritomo Flelov Laboratory of Nuclear Reactions, Dubna, Russia Japan Atomic Energy Agency, Tokai, Japan

Thank you.