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” Grad student in the Seaborg group Numerous important contributions 226 U Current data t 1/2 =0.35 s, E  =7.57 MeV

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= ) 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)

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

Physics Issues r 0 ~ 1.8  2R + D D  Initial Kinetic Energy of Fragments

New Developments

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). p frag p CN /2 Diagnostic for the occurrence of incomplete fusion A tool to study the mechanism of intermediate energy colliisions

Transfer Product Yields

Heavy Element Synthesis

Search for Element 112 in the 238 U( 48 Ca,3n) Reaction Y.T. Oganessian et al. reported (Eur. J. Phys A5, 63 (1999)) 231 MeV 48 Ca U    SF Two events were observed (t ½ = 81 (+147, -32) s) Dose = 3.5 x 10 18,  = 5.0 (+6.3, - 3.2) pb Somewhat unexpected decay mode

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

Chronology of Studies of 238 U( 48 Ca,3n) Reaction Vassilissa group reports synthesis of with  ~ 5 pb, t 1/2 ~ 3 m, decay =SF, E lab =231 MeV BGS group fails to find ,  upper ~ 0.9 pb, 0<t 1/2 <1000s, decay = ,SF, E beam =231 MeV Vassilissa group fails to find at E beam ~ 231 MeV,  upper ~ 2.2 pb Vassilissa group finds at E beam ~ 234 MeV,  ~ 4 pb, t 1/2 ~5.1 m, decay = SF DGFRS group fails to find 5 min SF activity, says is an  -emitter with t 1/2 ~ 6 s (produces this nucleus directly and in decay of and ) BGS group tries again to make at E beam ~ 236 MeV without success Swiss group fails to confirm DGFRS or Vassilisa results GSI group fails to confirm DGFRS or VASSILISSA results but finds one event (t~7 s, decay =SF,  =0.5 pb)--disagrees with everyone.

Summary of BGS Experiments

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

Summary of Experiments Vassilissa group is SF nucleus, with t 1/2 ~ 5 min,  ~ 4 pb DGFRS group is  emitter (SF < 10%), t 1/2 = 6 s,  ~ 2.5 pb GSI group is SF nucleus, t 1/2 ~ 5 s,  ~ 0.7 pb BGS group not found,  upper ~ 0.9 pb

Thanks, Vic