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Viola and the Heavy Elements

Viola and the Heavy Elements. W. Loveland Oregon State University. Vic’s Contributions to the Heavy Element Field. Vic’s Nucleus Systematics of the properties of the heaviest elements TKE release in fission Linear Momentum Transfer Transfer Product Yields. Vic’s Nucleus--The “Union Card”.

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Viola and the Heavy Elements

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  1. Viola and the Heavy Elements W. Loveland Oregon State University

  2. Vic’s Contributions to the Heavy Element Field • Vic’s Nucleus • Systematics of the properties of the heaviest elements • TKE release in fission • Linear Momentum Transfer • Transfer Product Yields

  3. Vic’s Nucleus--The “Union Card” • Grad student in the Seaborg group • Numerous important contributions • 226U Current data t1/2=0.35 s, E=7.57 MeV

  4. Systematics of the properties of the heaviest elements • Masses, Q, Q • V.E. Viola, Jr. and G.T. Seaborg, J. Inorg Nucl.Chem. 28, 697 (1966). • V.E. Viola, Jr., J. A. Swant, and J. Graber, At. Data and Nucl Data Tables 13, 35 (1974). (Z=50-118, A=130-311) • Lifetimes • V.E. Viola, Jr. and G.T. Seaborg, J. Inorg. Nucl Chem. 28, 741 (1966) • V.E. Viola, Jr. and B.D. Wilkins, Nucl. Phys. 82, 65 (1966)

  5. TKE Release in Fission V.E. Viola, Jr. Nucl. Data A1, 391 (1966) V.E. Viola, K. Kwiatkowski, and M. Walker, Phys. Rev. C 31 1550 (1985). Simple-Minded Approach Viola Systematics-1966 Viola systematics-1985 Simple fit to the data Pocket formula Note limits on range of applicability

  6. Physics Issues r0 ~ 1.8 2R + D D  Initial Kinetic Energy of Fragments

  7. New Developments

  8. Linear Momentum Transfer T. Sikkeland, E.L. Haines, and V.E. Viola, Jr., Phys. Rev 125, 1350 (1962) V,E. Viola, et al., Phys, Rev. C 26,178 (1982). pfrag pCN/2 • Diagnostic for the occurrence of incomplete fusion • A tool to study the mechanism of intermediate energy • colliisions

  9. Transfer Product Yields

  10. Heavy Element Synthesis

  11. Search for Element 112 in the 238U(48Ca,3n) Reaction • Y.T. Oganessian et al. reported (Eur. J. Phys A5, 63 (1999)) • 231 MeV 48Ca + 238U 286112 283112  SF • Two events were observed (t½ = 81 (+147, -32) s) • Dose = 3.5 x 1018,  = 5.0 (+6.3, -3.2) pb • Somewhat unexpected decay mode

  12. What is so special about 283112 and its synthesis? • 283112 occurs in the decay of 291116 formed in the 245Cm + 48Ca reaction. • 283112 occurs in the decay of 287114 formed in the 244Pu + 48Ca reaction. • 283112 should be the most easily reachable hot fusion product.

  13. Chronology of Studies of 238U(48Ca,3n) 283112 Reaction • 1999--Vassilissa group reports synthesis of 283112 with  ~ 5 pb, t1/2 ~ 3 m, decay =SF, Elab=231 MeV • 2002--BGS group fails to find 283112, upper~ 0.9 pb, 0<t1/2<1000s, decay =,SF, Ebeam =231 MeV • 2004--Vassilissa group fails to find 283112 at Ebeam ~ 231 MeV, upper ~ 2.2 pb. • 2004--Vassilissa group finds 283112 at Ebeam ~ 234 MeV,  ~ 4 pb, t1/2 ~5.1 m, decay = SF • 2004--DGFRS group fails to find 5 min SF activity, says 283112 is an -emitter with t1/2 ~ 6 s (produces this nucleus directly and in decay of 291116 and 287114.) • 2004--BGS group tries again to make 283112 at Ebeam ~ 236 MeV without success. • 2005--Swiss group fails to confirm DGFRS or Vassilisa results • 2005--GSI group fails to confirm DGFRS or VASSILISSA results but finds one event (t~7 s, decay =SF, =0.5 pb)--disagrees with everyone.

  14. Summary of BGS Experiments

  15. RESULTS NO SF events in any irradiation No EVR-- correlations ( T < 20 s) in any irradiation.

  16. Summary of Experiments • Vassilissa group 283112 is SF nucleus, with t1/2 ~ 5 min,  ~ 4 pb • DGFRS group 283112 is  emitter (SF < 10%), t1/2 = 6 s,  ~ 2.5 pb • GSI group 283112 is SF nucleus, t1/2 ~ 5 s,  ~ 0.7 pb • BGS group 283112 not found, upper ~ 0.9 pb

  17. Thanks, Vic

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