Matti Nurmia

Evidence for the possible synthesis of element 110 produced by the {sup 59}Co+{sup 209}Bi reaction

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.

Alpha decay properties of light einsteinium isotopes

Abstract The light einsteinium isotopes, with mass numbers 249, 248, 247, 246, 245 and 243, were produced by irradiating 249Cf with protons, 238U with 14N, 237Np with 12C and 233U with 14N, and have been studied by means of α-ray spectroscopy. An analysis of the complex α-peaks of the einsteinium isotopes gave new α-branchings. The tentative assignments of 7 2 + → 7 2 + , 9 2 + ) in the α-decay of 249Es, ( 7 2 + → 7 2 + , 9 2 + , 11 2 + ) in 247Es, ( 3 2 − → 7 2 + , 3 2 − , 5 2 − , 7 2 − ) in 245Es, and ( 3 2 − → 7 2 + , 3 2 − ) in 243Es were made.

Evidence for the synthesis of 267110 produced by the 59Co+209Bi reaction

Abstract 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.

The new nuclide nobelium-259

Abstract A new, relatively long-lived isotope of element 102 has been produced through the bombardment of 248 Cm with 18 O ions at both Oak Ridge and Berkeley. A maximum of approximately 20 nb occurs in the production cross section at a bombarding energy of 93 MeV. A total half-life of 58 ± 5 min was computed from the combined data of both laboratories. Five α-particle groups have been observed in the decay with the following energies and abundances: 7.685 (11%), 7.605(14%), 7.533 (23%), 7.500 (39%) and 7.455 MeV (13%). A spontaneous-fission branch of about 20% relative to the α-emission appears to accompany the decay. The atomic number was assigned on the basis of characteristic ion-exchange column behavior; the mass assignment was made from the growth of the α-decay daughter, 255 Fm, into chemically separated samples. The Z and A assignment is corroborated by Nuclear reaction data and consistent with α-decay energy systematies.

SEARCH FOR AN 80-ms SPONTANEOUS FISSION ACTIVITY IN BOMBARDMENTS OF 249Bk WITH 15N

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

Atom-at-a-time radiochemical separations of the heaviest elements: Lawrencium chemistry

The isotope260Lr, produced in reactions of18O with249Bk, was used to perform chemical experiments on lawrencium to learn more about its chemical properties. These experiments involved extractions with thenoyl trifluoroacetate, elutions from cation exchange resin columns with ammonium alpha-hydroxyisobutyrate, and reverse-phase chromatography using hydrogen di(2-ethylhexyl) orthophosphoric acid to investigate the chemical properties of Lr. The results from the elutions gave information about the ionic radius of Lr(III) which was found to elute very close to Er. An attempt to reduce Lr(III) with hydroxylamine hydrochloride was unsuccessful.

Superheavies in Nature ? Where and How to Look

In searching for superheavy elements in nature it is usually assumed that the SHE (1) follows the chemistry of its lighter homolog and (2) decays by spontaneous fission. The sensitivity of SHE detection can be substantially improved by replacing these assumptions by a consideration of the geo-chemical fractionation processes, and by using a mass spectrometer. A good candidate for a search would be element 112, eka-mercury. It is expected to be more volatile and more noble than Hg so that it may behave like a heavy rare gas and be concentrated in the earths atmosphere.

Actinide production from the interactions of sup 40 Ca and sup 44 Ca with sup 248 Cm and a comparison with the sup 48 Ca+ sup 248 Cm system

Excitation functions have been measured for production of isotopes of Th through Fm in bombardments of {sup 248}Cm with 231- to 323-MeV {sup 44}Ca ions and for the production of isotopes of Th through Cm in bombardments of {sup 248}Cm with 230- to 291-MeV {sup 40}Ca ions, respectively, using radiochemical methods. Upper production cross section limits were established for nuclides that were not positively detected. The experimental data were compared with the results of previous reaction studies in the systems {sup 40}Ca+{sup 248}Cm and {sup 48}Ca+{sup 248}Cm. The half-widths of the Gaussian isotopic distributions were about 2.5 mass numbers for above-target elements and 5 to 5.5 mass numbers for below-target elements in all three systems. The majority of the cross section for the production of above-target nuclides was assigned to predominantly quasielastic reactions, whereas below-target nuclides were formed in deeply inelastic and asymmetric quasifission reactions. The maxima of the isotopic distributions were shown by others to closely follow the minimum of the potential energy surface in experiments with {sup 48}Ca, whereas in reactions with {sup 40}Ca and {sup 44}Ca we found that a transfer of 4 to 5 protons in either direction was required to reach the minimum in potentialmorexa0» energy.«xa0less

Actinide production from the interactions of Ca-40 and Ca-44 with Cm-248 and a comparison with the Ca-48 + Cm-248 system

Excitation functions have been measured for production of isotopes of Th through Fm in bombardments of {sup 248}Cm with 231- to 323-MeV {sup 44}Ca ions and for the production of isotopes of Th through Cm in bombardments of {sup 248}Cm with 230- to 291-MeV {sup 40}Ca ions, respectively, using radiochemical methods. Upper production cross section limits were established for nuclides that were not positively detected. The experimental data were compared with the results of previous reaction studies in the systems {sup 40}Ca+{sup 248}Cm and {sup 48}Ca+{sup 248}Cm. The half-widths of the Gaussian isotopic distributions were about 2.5 mass numbers for above-target elements and 5 to 5.5 mass numbers for below-target elements in all three systems. The majority of the cross section for the production of above-target nuclides was assigned to predominantly quasielastic reactions, whereas below-target nuclides were formed in deeply inelastic and asymmetric quasifission reactions. The maxima of the isotopic distributions were shown by others to closely follow the minimum of the potential energy surface in experiments with {sup 48}Ca, whereas in reactions with {sup 40}Ca and {sup 44}Ca we found that a transfer of 4 to 5 protons in either direction was required to reach the minimum in potentialmorexa0» energy.«xa0less

Excitation functions for production of heavy actinides from interactions ofO16withCf249

Excitation functions have been measured for the production of isotopes of Bk through Fm in bombardments of