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An experiment to synthesize element 110 by the {sup 59}Co+{sup 209}Bi reaction has been performed at the SuperHILAC at the Lawrence Berkeley Laboratory. One event with many of the expected characteristics of a successful synthesis of {sup 267}110 was observed. This event corresponds to a production cross section of about one picobarn.

An experiment to synthesize element 110 by the 59 Co+ 209 Bi reaction has been performed at the SuperHILAC at the Lawrence Berkeley Laboratory. One event with many of the expected characteristics of a successful synthesis of 267 110 was observed. This event corresponds to a production cross section of about one picobarn.

Nitschke, M Fowler, A. Nurmia, .L. P. Somerville, Landrum, . W,. Lo!Jghee{;\, J, Silva, .and Eskola TWO-WEEK LOAN COPY This is a Library Circulating Copy wh may be borrowed two weeks. For a personal retention copyy call Divisiony Ext 6782. Preoan~d for the U.S. Department of Energy under Contract W-1405-ENG-48

We report the first measurement of Na and Na/sup +/ autoionization spectra following collisions of 1-MeV He/sup +/ ions on selectively excited Na 3p /sup 2/P/sub 3/2/ target atoms. The atomic states were populated with a c.w. dye laser which was tuned to the Na 3s /sup 2/S/sub 1/2/..-->..Na 3p /sup 2/P/sub 3/2/ transition. The simultaneous laser-ion beam excitation technique produces significant intensity variations particularly for the decay of the Na/sup +/ 2s2p /sup 6/3s /sup 1,3/S and the Na/sup +/ 2s2p /sup 6/3p /sup 1,3/P states. The technique may provide additional information for line identification, excitation mechanisms, and angular distribution measurements.

The authors have measured the mean life of the 2p4(1S0)3s2S1/2 state in neutral fluorine to be 0.31 ns using the beam-foil technique. Earlier work had indicated the possibility of superradiance from this state. The combination of these measurements and theory indicates a low autoionisation rate of about three times the radiative decay rate. The authors have also measured the mean life of the same level in isoelectronic neon.

In a recent spectroscopic study (D. E. Holmgren et al., Phys. Rev. A 31, 677 (1985)), many metastable core-excited quartet levels in Na I have been identified, and based on calculated decay rates (both radiative and autoionizing) some of these levels have been suggested for use in an extreme ultraviolet (xuv) laser. In order to test the theoretical calculations we have used the beam-foil technique to determine experimental lifetimes for eight quartet levels in the core-excited configurations 2p/sup 5/3s3d and 2p/sup 5/3s4s. The agreement between theory and experiment is within a factor of 2, but with systematic discrepancies.

We have found several new spontaneous fission (SF) activities and suggested assignments for some of them to rutherfordium (element 104) isotopes. Their half-lives and production cross sections have been measured by collecting recoils on a moving nickel or steel tape and transporting them past stationary mica track detectors at known velocities. The following tentative assignments are based on several cross bombardments and comparisons between experimental and calculated production cross sections: $^{256}\mathrm{Rf}$(9\ifmmode\pm\else\textpm\fi{}2 ms), $^{257}\mathrm{Rf}$(3.8\ifmmode\pm\else\textpm\fi{}0.8 s, 14\ifmmode\pm\else\textpm\fi{}9% SF), $^{258}\mathrm{Rf}$(13\ifmmode\pm\else\textpm\fi{}3 ms), $^{259}\mathrm{Rf}$(3.4\ifmmode\pm\else\textpm\fi{}1.7 s, 9\ifmmode\pm\else\textpm\fi{}3% SF), $^{260}\mathrm{Rf}$(21\ifmmode\pm\else\textpm\fi{}1 ms), and $^{262}\mathrm{Rf}$(47\ifmmode\pm\else\textpm\fi{}5 ms). Presently we are unable to assign several other new spontaneous fission activities with half-lives of \ensuremath{\sim}15 ms, \ensuremath{\sim}22 ms, \ensuremath{\sim}100 ms (Zl104), \ensuremath{\sim}1.6 s, \ensuremath{\sim}5 s, \ensuremath{\sim}5 s, \ensuremath{\sim}30 s, and \ensuremath{\sim}47 s. Contrary to other observations, we have not found any indication for an 80-ms spontaneous fission activity, earlier credited to the spontaneous fission decay of $^{260}\mathrm{Rf}$, in reactions in which we expected to produce this isotope. Our measurements support a shift in the spontaneous fission half-life systematics at element 104, first proposed by Flerov and Oganessian et al. and later predicted by Randrup et al. and Baran et al. and attributed to the disappearance of the second hump of the double-humped fission barrier and a weakening of the 152-neutron subshell.

We have measured the light yields and polarizations of the light emitted from several Balmer transitions in atomic hydrogen following beam foil excitation of protons at energies of 50 to 150 kev. The polarizations have been measured as a function of distance downbeam from the exciter foil for several transitions. The measurements indicate a very strong initial alignment which is then perturbed by surface fields out to several mm from the surface.