DETERMINATION OF THE ABSOLUTE FISSION YIELD OF Ba140 IN THERMAL NEUTRON FISSION OF U235

The absolute fission yield of Ba140 in the thermal neutron fission of U235 has been determined to be (6.32 ± 0.24)%. The reaction B10(n, α)Li7 was used as a neutron monitor and the B10/B11 ratio determined mass spectrometrically before and after neutron bombardment. The Ba140 disintegration rate was determined using 4π counting techniques. The half-life of La140 has been found to be 40.31 ± 0.06 hr.

ISOTOPE EFFECTS IN THE COMBUSTION OF CARBON MONOXIDE

The relative rates of reaction of C12O, C13O, and C14O with oxygen have been measured. When the oxidation proceeds mainly on the walls of the containing vessel the relative rates for C13O and for C14O compared to C12O are respectively 0.985 and 0.959. When reaction proceeds mainly in the gas phase there is no isotope effect within experimental error.

CHLORINE ISOTOPE EFFECT IN REACTIONS OF TERT-BUTYL CHLORIDE

When tert-butyl chloride reacts with either alcoholic silver nitrate or aqueous alcoholic sodium hydroxide the Cl35 compound reacts faster than the Cl37 compound. The ratio of the rates of reaction is[Formula: see text]

A NOTE ON THE PREPARATION OF CHLORINE GAS CONTAINING Cl36

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THE INDEPENDENT YIELD OF Xe135 PRODUCED IN THE FISSION OF NATURAL URANIUM BY PILE NEUTRONS

Fission of uranium yields Xe135 by two routes: direct production and production by the β-decay of I135. The amount produced directly (independent yield) has been measured by comparison with the amount produced from I135. The independent fission yield of Xe135 is found to be 2.7 ± 1.0% of the cumulative yield of I135. Assuming this latter quantity to be 5.6% of all fissions, the independent yield of Xe135 is ∼0.15%. The half-life of Xe135 has been measured as 9.13 ±.05 hr.

THE FISSION YIELD OF I131 IN THE THERMAL NEUTRON FISSION OF U235

The fission yield of I131 has been investigated using improved extraction techniques and disintegration rate measurements. The value obtained for the fission yield is (3.1 ± 0.1)%. This is relative to a Ba140 reference fission yield of 6.1%. The half-life for I131 has been determined and found to be 8.05 ± 0.01 days.

ISOTOPE EFFECTS: REACTION AT THE CARBONYL GROUP

It is shown that benzophenone containing the C14 O group reacts with 2,4-dinitrophenylhydrazine more slowly than does ordinary benzophenone. The ratio of the rate constants is 1.099 ±.011 at 27.8 °C.