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Katsuhisa Nishio Advanced Science Research Center Japan Atomic Energy Agency Tokai, JAPAN

Mass Asymmetric Fission of Iridium Nucleus. Mass Asymmetric Fission of Nucleus Produced in 7 Li + 186 W. Katsuhisa Nishio Advanced Science Research Center Japan Atomic Energy Agency Tokai, JAPAN. ARIS2014 Tokyo. ①　. ②　. ③　. ⑥　. ⑤　. ④.

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Katsuhisa Nishio Advanced Science Research Center Japan Atomic Energy Agency Tokai, JAPAN

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  1. Mass Asymmetric Fission of Iridium Nucleus Mass Asymmetric Fission of Nucleus Produced in 7Li + 186W Katsuhisa Nishio Advanced Science Research Center Japan Atomic Energy Agency Tokai, JAPAN ARIS2014 Tokyo

  2. ①　 ②　 ③　 ⑥　 ⑤　 ④ ①　K. Nishio, K. Hirose, I. Nishinaka, H. Makii, R. Orlandi,R. Léguillon, J. Smallcombe, S. Mitsuoka, T. Ishii, H. Ikezoe ② A. Andreyev ③ N. Tamura, S. Goto ④T. Ohtsuki ⑤I.Tsekhanovich ⑥P. Möller

  3. Properties for Low-Energy Fission Region of our interest I: beta-delayed fission of A~180-200 N/Z~1.22-1.3: Tl,Bi, At, Fr ISOLDE(CERN) A. Andreyev et al., Phys. Rev. Lett.105, 252502 (2010). Z=82 Z=82 Z=82 Z=82 180Hg N/Z=1.25 - particle induced x - e.m. –induced E*~11 MeV 187Ir 196Au

  4. 180Hg Calculated by P. Möller (LANL) and J. Randrup (LBNL) Calculated Fission Fragment Yield 193Ir 7Li + 186W  193Ir* P. Möller,10th ASRC International Workshop, “ Nuclear Fission and Structure of Exotic Nuclei ”, 2013.March, Tokai, Japan

  5. JAEA at Tokai and Tandem Facility Tokai Campus, JAEA Tokyo 20 MV Tandem accelerator (20UR) J-PARC Tandem facility

  6. Time difference signal of FFs in 7Li + 186W MWPC1 Ec.m.= 65.5MeV Fragment 1 44o 40.0 MeV 7Li Beam 186W Counts 30.0 MeV Fragment 2 MWPC2 Time difference (ch)

  7. Fragment Mass Distributions in 7Li + 186W Elab 68.0 MeV Fusion reaction is assumed 7Li + 186W  193Ir* 41.5 MeV Events (u) 31.1 MeV 83As 110Ru N = 50 N = 66 Fragment Mass (u)

  8. Folding Angle between Fission Fragments Beam Elab = 31.1 MeV Complete Fusion 7Li + 186W θfold =169o FF 1 FF 2 θ1 Counts Recoiled FissioningNucleus θ2 θfold = θ1 + θ2 (deg)

  9. Analysis assuming fusion-fission 7Li + 192Os  199Au* 7Li + 186W  193Ir* θfold, =167.9o θfold =167.5o Ebeam = 41.5 MeV Folding Angle (deg.) Folding Angle (deg.) TKE (MeV) TKE (MeV) Z=118 <TKEViola> =134 MeV <TKEViola> =129 MeV Fragment Mass (u) Fragment Mass (u) Viola Formula from Phys. Rev. C 31, 1550 (1985)

  10. 7Li + 186W, 192Os 7Li + 186W 7Li + 192Os 180 170 160 180 170 160 EBeam = 64.0 MeV σfiss = 67 μb 110 μb 180 170 160 180 170 160 41.5 MeV qfold (deg) 2.1 μb 14 μb -20 0 20 180 170 160 31.1 MeV 0.8 μb -20 0 20 dT (ns) dT (ns)

  11. Break-up Fusion 7Li  3H + 4He (Q= -2.467 MeV) p + 192Os 190Ir 191Ir 193Ir 187Ir 188Ir 189Ir 192Ir 193Ir Counts 189Os 190Os 190Os 186Os 187Os 188Os 191Os 192Os Fragment Mass (u) 188Re 189Re 189Re 185Re 186Re 187Re 186W( 7Li, t)190Os* 186W( 7Li, α)189Re * 184W 185W 186W

  12. Break-up Fusion and Fission 4He 4He 3H 3H 186W 7Li 3H + 186W 189Re* Fragment 2 4He + 186W 190Os* Fragment 1

  13. Fission Barrier Height for 189Re and 190Os 189Re, 190Os Fission Barrier is 25 MeV 189Re*or190Os* should have excitation energy larger than 25 MeV P. Möller, 16th ASRC International Workshop, “ Nuclear Fission and Decay of Exotic Nuclei ”, 2014.March, Tokai, Japan

  14. Folding Angle at E* = 25 MeV of Fissioning Nucleus 7Li +186W = 193Ir* 180 170 160 Elab 186W(7Li, α) 189Re*, θα = 25o 64.0 MeV 186W(7Li, t) 190Os*, θt= 45o 180 170 160 41.5 MeV 186W(7Li, α) 189Re*, θα = 45o qfold (deg) 186W(7Li, t) 190Os*, θt= 45o 180 170 160 186W(7Li, α) 189Re*, θα = 55o 31.1 MeV E*max = 36 MeV dT (ns) -20 0 20

  15. Setup for Break-up Fusion Induced Fission MWPC1 186W ΔE-E 7Li Beam θLAB 189Re*… t, α Target 7Li E ΔE MWPC2

  16. Summary Mass-asymmetric fission was observed for nucleus produced in 7Li +186W. The fissionig nucleus could be populated by break-up fusion. Coincidence experiment between particle and both fission fragments is planned.

  17. Properties for Low-Energy Fission 180Hg  A. Andreyev et al., Phys. Rev. Lett.105, 252502 (2010).

  18. Folding Angle Distribution at E* = 25MeV 180 170 160 Elab 7Li +186W = 193Ir* 186W(7Li, t) 190Os*, θt= 45o, 170.0 64.0 MeV 186W(7Li, α) 189Re*, θα = 25o, 173 180 170 160 186W(7Li, t) 190Os*, θt= 45o,170.0o 41.5 MeV 186W(7Li, α) 189Re*, θα = 45o , 172 qfold (deg) E* max = 26 MeV 180 170 160 186W(7Li, t) 190Os*, θt= 45o, 170.0 31.1 MeV 186W(7Li, α) 189Re*, θα = 55o, 172 E*max = 36 MeV dT (ns) -20 0 20

  19. Summary

  20. Multi-nucleon Transfer Induced Fission 18O + 232Th Coincidence between particle and fission fragments F 15N O N C 232Th(18O,15N) 235Pa*  Transfer of 3H B Be Esum (MeV)

  21. Fragment Mass Distributions for 3H Transfer 232Th(18O,15N) 235Pa* →Fission Excitation energy (MeV) Counts Fragment mass yield (u)

  22. Fragment Mass Distributions for 232Th* 232Th(18O, 18O)232Th* Excitation energy (MeV) Fragment mass yield (u)

  23. Multi-nucleoon Transfer Induced Fission 18O + 232Th Coincidence between particle and fission fragments F O N C B Be Esum (MeV)

  24. New Region for Mass Asymmetric Fission 180Hg 100 80 A.Andreyevet al., Phys. Rev. Lett.105, 252502 (2010). T. Ichikawa et al., Phys. Rev.C.86, 024610 (2012).

  25. Theoretical Mass Yield 189Ir 193Ir

  26. Fission Ｑ-value Saddle Point Shape Large Fission Probability 258Fm 1980 238U 2010 Q-value for Fission (MeV) 193Ir Present 160Gd Small Fission Probability Fragment Mass (u)

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