H.L. Hall

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.

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.

Nuclear penetration effects in 233U

Abstract Results from precise measurements of the K conversion coefficients for the 300, 312 and 340 keV γ-rays from 233 Pa β − decay reveal nuclear penetration effects for these predominantly M1 transitions. The experimental conversion coefficients, which are about 18% smaller than values from theory neglecting those effects, remove a previous inconsistency in the transition-intensity balance for the decay scheme of 233 Pa and allow a total (6±2)% β − branch to the ground and first-excited states. The measured value of (8.8 ±1.4%) for this intensity and the total K X-ray intensity deduced from the present K conversion coefficients, both confirm the revised decay scheme.