Adolf F. Voigt

Isomer ratio measurements for 91Mo, 137Ce and 141Nd produced by (γ, n) and (γ, 3n) reactions

Abstract Isomer ratios for the reactions A+1Z(γ, n)AZ and A+3 Z(γ, 3n) A Z, ( A Z = 91 Mo , 137 Ce and 141 Rm ) have been deduced from residual radioactivity measurements of separated targets irradiated with 70 MeV bremsstrahlung. More uniform production of the AZ isomeric pair states was observed by the (γ, 3n) reaction than by the (γ, n) reaction. This behavior is discussed in terms of the nuclear photoabsorption process and the neutron emission modes of the compound nucleus.

Influence of Structure on Gaseous Products from C11 Recoil Reactions in C6 Hydrocarbons

Results are presented on the yields of gaseous products resulting from recoil reactions of C11 in various C6 hydrocarbons: benzene, n‐hexane, 2‐methylpentane, and 2,2‐dimethylbutane. The C11 was produced by the C12 (γ, n)C11 reaction in the target molecule. The radiation time and dose were varied, and iodine was added as a scavenger. Comparison was made with similar results on cyclohexane. In all cases, acetylene is the most abundant product, but as branching in the molecule increases, other products, principally ethylene and ethane, become increasingly important. The results are in agreement with a mechanism involving the insertion of an energetic C11 or C11H group into a C–H bond, followed by bond rupture in the resulting intermediate.

Counting alpha particles from the 6Li+n reaction by track-etch methods

Abstract The track etch-spark counting technique using thin cellulose nitrate films has been demonstrated to be successful for measuring approximately 2 MeV alpha particles from a 210 Po alpha source and from the 6 Li(n,α) 3 H reaction. Precision of measurement was found to approach that of counting statistics and the linearity of response extended to approximately 2000 spark counts/cm 2 of detector film. The potential application of the technique to a surface activation analysis by the (n,α) reaction was investigated by irradiating 6 LiF thermoluminescence detector crystals in a neutron flux using an evacuated irradiation chamber.

Target developments at TRISTAN

Abstract Developments at TRISTAN to make available non-gaseous fission-product activities have progressed along three approaches: UF 4 samples to replace the traditional stearate sample, He-jet system connected to the separator ion source, and modification of the ion beam optics to allow placement of the ion source in the neutron beam. The status of each approach is presented in the light of the resulting availability of non-gaseous fission products of interest for systematic studies of nuclear structure of neutron-rich nuclei far from stability.

The half-life of antimony-125☆

Abstract The half-life of antimony-125 separated from uranium fission products has been determined to be 2·6 ± 0·1 years by measurements on a Lauritsen electroscope over a 5 year period.

The extraction of mercury(II) iodide

Abstract The extraction of mercury(II) iodide into benzene at various acid and iodide concentrations was used as a means of determining the formation constants of the HgI3− and HgI4 = species. Radioactive tracer techniques were used to measure the extent of extraction at low mercury concentrations. With reasonable assumptions about activity coefficients the thermodynamic values of the constants for the formation of HgI3− and HgI4 = from HgI2 and I− were found to be 5·0 × 103 and 5·1 × 105, respectively.

Radiochemical studies of mercury and its ions in dilute solutions

iii The behavior of the mercurous ,ion has been studied in dilute aqueous solutions. The ion was found to be unstable toward dismutation according to the equation: K Hg~+ ~ Hg++ + Hg(aq) • Values of 5.3 X lo-9 and 5.6 X lo-9 have been measured for . , I the dismutation constant K at 2~C by making ·use or a .radi.o active tracer· technique in which mercury was distributed between non-polar solvents and dilute aqueous solutions of mercurous nitrate. The above values for the dismutation constant are in fair agreement with the values 1.8 x lo-9 to 3.6 x lo-9 which were calculated by a different approach. The latter ~ figures were obtained as the product of the reported con.. centration ratios (?g+j I ~g~+] , in the presence of liquid mercury, and the solubility of the metal in aqueous solutions determined in this study (3.0 x lo-7 g atoms/liter). Although the possibility of dissociation of the mercurous dimer into monomeric mercurous ions cannot be completely ex~luded, the results of this study can be satisfactorily interpreted without considering this effec·t. The results indicate that a dissociation constanr as large as 1 x lo-7 is highly unlikely. The solubility of mercury in several organic solvents was determined and compared with solubilities calculated

Chemical effects of photonuclear reactions in the propyl bromides

Two new photonuclear reactions are reported, Br79(γ,2n)Br77 and Br79(γ,3n)Br76.The organic retention following the Br81(γ,n)Br80m reaction in liquid n‐ and isopropyl bromides was found to be 47 and 36%, respectively, appreciably higher than reported values following the Br79(n,γ)Br80m reaction. Higher retentions were also noted for irradiations of the solid bromides. The relative yields of individual organic products were determined for irradiations of both liquid and solid and were in many respects in striking agreement with data from activation by (n,γ) reaction and isomeric transition. In solid n‐propyl bromide the (γ,n) and (γ,3n) reactions gave the same ratio of parent compound to total organic yield.Data on the scavenger effect show that thermal recombination reactions occur in both liquid and solid. Marked increases are shown in the thermal organic yield with only slight increases in the nonthermal retention for both bromides for (γ,n) compared to (n,γ) activation. The reasons for these increases a...