John D. Despotopulos

Production and separation of carrier-free 7Be

A high-purity carrier-free (7)Be was efficiently isolated following proton bombardment of a lithium hydroxide-aluminum target. The separation of beryllium from lithium and aluminum was achieved through a hydrochloric acid elution system utilizing cation exchange chromatography. The beryllium recovery, +99%, was assessed through gamma spectroscopy while the chemical purity was established by mass spectrometry. The decontamination factors of beryllium from lithium and aluminum were determined to be 6900 and 300, respectively.

Recent advances and results from the solid radiochemistry nuclear diagnostic at the National Ignition Facility

The solid debris collection capability at the National Ignition Facility has been expanded to include a third line-of-sight assembly. The solid radiochemistry nuclear diagnostic measurement of the ratio of gold isotopes is dependent on the efficient collection of neutron-activated hohlraum debris by passive metal disks. The collection of target debris at this new location is more reliable in comparison to the historic locations, and it appears to be independent of collector surface ablation.

Distribution of collected target debris using the large area solid debris radiochemistry collector

A large area solid radiochemistry collector was deployed at the National Ignition Facility (NIF) with a collection efficiency for post-shot, solid target debris of approximately 1% of the total 4π solid angle. The collector consisted of a 20-cm diameter vanadium foil surrounded by an aluminum side-enclosure and was fielded 50 cm from the NIF target. The collector was used on two NIF neutron yield shots, both of which had a monolayer of 238U embedded in the capsule ablator 10 μm from the inner surface. Fission and activation products produced in the 238U were collected, and subsequent analyses via gamma spectroscopy indicated that the distribution of fission products was not uniform, with peak and valley fission products preferentially collected on the vanadium and low- and high-mass fission products primarily located on the aluminum side-enclosure. The results from these shots will be used to design future nuclear data experiments at NIF.

Fractionation of copper activation products in debris samples from the National Ignition Facility

Nuclear fusion experiments performed at the National Ignition Facility produce radioactive debris, arising in reactions of fast neutrons with the target assembly. We have found that postshot debris collections are fractionated, such that isotope ratios in an individual debris sample may not be representative of the radionuclide inventory produced by the experiment. We discuss the potential sources of this fractionation and apply isotope-correlation techniques to calculate unfractionated isotope ratios that are used in measurements of nuclear reaction cross sections.

Production and separation of carrier-free 7 Be

A high-purity carrier-free (7)Be was efficiently isolated following proton bombardment of a lithium hydroxide-aluminum target. The separation of beryllium from lithium and aluminum was achieved through a hydrochloric acid elution system utilizing cation exchange chromatography. The beryllium recovery, +99%, was assessed through gamma spectroscopy while the chemical purity was established by mass spectrometry. The decontamination factors of beryllium from lithium and aluminum were determined to be 6900 and 300, respectively.

Production and separation of carrier-free ⁷Be.

A high-purity carrier-free (7)Be was efficiently isolated following proton bombardment of a lithium hydroxide-aluminum target. The separation of beryllium from lithium and aluminum was achieved through a hydrochloric acid elution system utilizing cation exchange chromatography. The beryllium recovery, +99%, was assessed through gamma spectroscopy while the chemical purity was established by mass spectrometry. The decontamination factors of beryllium from lithium and aluminum were determined to be 6900 and 300, respectively.

Characterization of Group 5 dubnium homologs on diglycolamide extraction chromatography resins from nitric and hydrofluoric acid matrices

A diglycolamide-based resin was characterized for Group 5 (Ta, Nb and pseudo-homolog Pa) separation from Group 4 (Hf and Zr) and tri-valent actinides (Am). The batch uptake of the radionuclides of interest were determined for HNO3/HF matrices and the results were used to develop a column separation method that could be used for element 105 (Db) purification chemistry. Tantalum is significantly retained by the TODGA resin, while Pa/Nb show little to no retention. The affinity for Ta decreases as a function of increased [HNO3], while Zr/Hf (and Am) affinities increase under the same conditions. Adsorption of Ta to polypropylene vials and column frits became a significant focus of this work following several observations made during the course of the column separation method development. All of the Group 5 elements were separated from Group 4 and Am while Ta may be completely isolated from Nb/Pa with the TODGA resin with improvements in column parameters: column height and bed volume.