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F. Minato A , S. Chiba A , K. Hagino B

Fission barrier of uranium including Λ hyperon. F. Minato A , S. Chiba A , K. Hagino B. A. Japan Atomic Energy Agency B. Tohoku Univ. Nucl.Phys.A831, 150 (2009). Nucl . Phys. A856, 55 (2011) . Table of Contents. １ ． Λ impurity effects ２． Motivation

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F. Minato A , S. Chiba A , K. Hagino B

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  1. Fission barrier of uranium including Λ hyperon F. MinatoA, S. ChibaA, K. HaginoB A. Japan Atomic Energy Agency B. Tohoku Univ. Nucl.Phys.A831,150 (2009) Nucl. Phys. A856, 55 (2011)

  2. Table of Contents １．Λ impurity effects ２．Motivation ３．fission barrier & density distribution ４．Summary

  3. Λ Impurity effect • Shrinkage • Level • cluster model • experiment p Rcore-(np) density distribution α n Rcore-(np) T. Motoba et al., Prog. Theor. Phys. 70, (1983) 189. E. Hiyama et al., Phys. Rev. C59, (1999) 2351. H. Tamura et al., NPA754, 58(2005) 6Li

  4. Λ Impurity effect • RPA with degree of freedom of Λ Dipole motion of 18ΛΛO peak at E= 12.8 MeV Λ [1p(1s)-1] 80 % n&p [1d5/2(1p3/2)-1] 20% FM&KH, Physical Review C 85, 024316 (2012)

  5. Motivation • What is impurity effect like in Λ hyper-actinide? • 1) production of Λ in nuclei • 2) decay of Λ in nuclei • K-+ 238U  239ΛU + π- + 178 MeV • Λ + N  N + N + 190 MeV Λlife-time~10-10sec • High energy is released in production & decay of Λ ⇒ promote Fission & destruction of Fission Product Fragment distribution after Λ weak decay in 13853I  change of “final” fission yield

  6. Fission of Hyper-uranium • Experiment • Theory T.A.Armstrong, J.P.Bocquet, G.Ericsson, et al. Phys. Rev. C 47, 1957 (1993). H.J. Krappe and V.V. Pashkevich, Phys. Rev. C 53,1025 (1996). heavy fragment light fragment F.F. Karpeshin, C.G. Koutroulos, M.E. Grypeos, Nucl. Phys. A595, 209 (1995). H.J. Krappe and V.V. Pashkevich, Phys. Rev. C 47, 1970 (1993). Λ-attachment probability Fission barrier of Hypernuclei ??

  7. r Skyrme-Hartree-Fock z 1. reflection asymmetry 2. quadrupole constraint NNinteraction: SkM* parameter set Skyrme-type interaction for ΛN & ΛΛinteraction 9 parameters: t0Λ, x0Λ, t1Λ, t2Λ, t3Λ, λ0, λ1, λ2, λ3 ◆ΛN interaction M. Rayet, Nucl. Phys. A367 (1981) 381 ◆ΛΛinteraction Lanskoy PRC58, 3351(1998)

  8. Skyrme-Hartree-Fock ΛN: 1. B.E. of 5ΛHeand 209ΛPb 2. m*Λ/mΛ =0.8 in nuclear matter 3. energy difference between0+ and 1+ of4ΛHe 4. W0Λ=0 Y. Yamamoto, H. Bando, and J. Zofka, Prog. Theor. Phys. 80, (1988) 757. YBZ4 set: t0Λ=-315.3, t1Λ=23.14, t2Λ=-23.14, t3Λ=2000, x0Λ=-0.109 ΛΛ : Λ bond energy ΔBΛΛ=BΛΛ-2BΛ ΔBΛΛ(13BΛΛ) = 4.8 or 0.6 MeV λ2=λ3= 0 cf. FM & SC Nucl. Phys. A856, 55 (2011) range of “equivalent” single gaussian potential Lanskoy PRC58, 3351(1998)

  9. Result Fission barrier height single-Λ 239ΛU double-Λ 240ΛΛU 0.61-0.63↑ 0.27↑ ↑ 0.53 ↑ 0.91-1.03 x 2

  10. Why Increase of Bf? Λ Energy Core Energy 238U 239ΛU 0.5 0.25 Energy of Λ particle increases due to transfer to fragment with smaller mass Change of Core Energy SMALL

  11. Density distribution of 239ΛU ground state outer barrier Q2=200 barn Λ particle moves to heavier fragment

  12. Density distribution of 240ΛΛU FM & SC Nucl. Phys. A856, 55 (2011) ground state Q2=200 barn CORE Λ(SΛΛ1) range μ=0.61fm Λ(SΛΛ3) range μ=1.61fm

  13. SUMMARY Calculate Fission Barrier height & density distribution of 239ΛU, 240ΛΛU with Skyrme-Hartree-Fock approach ◆Fission barrier height Barrier height is increased InnerBf : 0.27 MeV↑ OuterBf : 0.50 MeV↑ InnerBf : 0.61~0.63 MeV↑ OuterBf : 0.91~1.03 MeV↑ ◆Density distribution Λ particle(s) move to heavier fragment in adiabatic approximation

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