Abstract
A flowing-water target was irradiated with a 150 MeV/nucleon beam of
78
Kr at the National Superconducting Cyclotron Laboratory to produce
77
Kr and
76
Kr. Real-time gamma-imaging ...measurements revealed the mass transport of the krypton radioisotopes through the target-water processing, or “isotope harvesting”, system. The production rates were determined to be 2.7(1) × 10
–4
nuclei of
76
Kr and 1.18(6) × 10
–2
nuclei of
77
Kr formed per incident
78
Kr ion. Utilizing an off-gas processing line as part of the isotope harvesting system, a total of 7.2(1) MBq of
76
Kr and 19.1(6) MBq of
77
Kr were collected in cold traps. Through the decay, the daughter radionuclides
76
Br and
77
Br were generated and removed from the traps with an average efficiency of 77 ± 12%. Due to the differences in half-lives of
76
Kr and
77
Kr, it was possible to isolate a pure sample of
76
Br with 99.9% radionuclidic purity. The successful collection of krypton radioisotopes to generate
76
Br and
77
Br demonstrates the feasibility of gas-phase isotope harvesting from irradiated accelerator cooling-water. Larger-scale collections are planned for collecting by-product radionuclides from the Facility for Rare Isotope Beams.
The quest to improve the quality of nuclear data, such as half-lives, transition yields, and reaction cross-sections, is a shared endeavor among various areas of nuclear science. 48V is a vanadium ...isotope for which experimental data on neutron reaction cross-sections is needed. However, traditional isotope production techniques cannot produce 48V with high enough isotopic purity for some of these measurements. “Isotope harvesting” at the Facility for Rare Isotope Beams (FRIB) is a new isotope production technique that could potentially yield 48V with the necessary purity for such studies. In this case, 48Cr would be collected and allowed to generate 48V that can be separated from undecayed 48Cr to yield highly pure 48V. Thus, any protocol for producing pure 48V via isotope harvesting would involve utilizing a separation technique that can effectively separate 48Cr and 48V. In this study, the radiotracers 51Cr and 48V were used to develop possible radiochemical separation methodologies, which can be translated to obtain high purity 48V via this novel isotope production method. The developed protocols utilize either ion exchange or extraction chromatographic resins. Separations of 51Cr and 48V with AG 1-X8 anion exchange resin respectively resulted in recoveries of 95.6(26)% and 96.2(12)% with radionuclidic purities of 92(2)% and 99(1)%. An even more effective Cr and V separation was obtained with an extraction chromatographic resin (TRU resin) and 10 M HNO3 loading solution. Here, 51Cr and 48V respectively had recoveries of 94.1(28)% and 96.2(13)% with high radionuclidic purities (100(2)% and 100(1)%) in small volumes (8.81(8) mL and 5.39(16) mL). This study suggests that, to maximize the yield and isotopic purity of 48V, the best production protocol would involve utilizing two separations with TRU resin and 10 M HNO3 to isolate 48Cr and purify the generated 48V.
•Two novel and effective separation procedures were developed for producing pure 48V.•Both methods successful separated 51Cr and 48V with high recoveries (>94%).•Pure 51Cr and 48V fractions (100% radionuclidic purity) obtained using TRU resin.
At the Facility for Rare Isotope Beams (FRIB), an oven-ion source combination was used to create rare isotope beams in support of the stand-alone user beam program of the ReAccelerator (ReA) ...facility. This ion source, called Batch-Mode Ion Source (BMIS), was loaded with enriched stable nuclides (30Si, 50Cr, and 58Fe) and long-lived radionuclides (26Al, 32Si). The introduced samples, herein designated as source samples, were thermally volatilized in the BMIS oven, and then ionization was used to generate the required beams. Owing to the different chemical behavior of the used samples, it was important to tailor the sample loading process for each desired beam species. An important parameter here is the volatility of the introduced species, which influences the adequate release of the isotope of interest. Additionally, any co-present, volatile components will affect the ion yields of the desired isotope, while isobaric contaminants will decrease the beam purity. To manufacture isotope source samples that meet these characteristics, various chemical methodologies were developed. All prepared samples were successfully used in BMIS to deliver beams for various user beam experiments. The here-established sample preparation techniques will greatly aid future efforts in developing offline rare-isotope beams.
•Preparation of stable (30Si, 50Cr, 58Fe) and radioactive (26Al, 32Si) source samplesfor the offline beam program at FRIB.•High-yield transformation of the chemical species of 26Al, 50Cr, and 58Fe to compounds that are suitable BMIS source samples.•Effective cation exchange-based method developed to strip the high Na-matrix of the 30Si and 32Si samples.•Reduction of the isobaric 32S contaminant in the 32Si samples by an anion exchange-based procedure.
A sample of 47Ca produced through isotope harvesting at the National Superconducting Cyclotron Laboratory was used to measure branching ratios of 7.17(5)%, 7.11(5)%, and 75.0(5)% for the 489.2, ...807.9, and 1297.1 keV characteristic gamma rays, respectively. Based on these updated branching ratios, the ground state to ground state 47Ca to 47Sc beta decay branching ratio has been indirectly measured as 17.7(5)% and the ground state to 1297.1 keV excited state as 82.2(5)%. Here these values represent a greatly increased precision for all five branching ratios compared to the currently accepted values. The measurements presented here were made relative to the ingrown 47Sc daughter in a47Ca sample and the well-established 159.4 keV gamma-ray branching ratio and the half-life for the decay of 47Sc. These measurements were supported by verifying that the half-lives measured from characteristic gamma-ray peaks over multiple spectra for both 47Ca and 47Sc were consistent with previously reported values. Additionally, the half-lives of both 47Ca and 47Sc were independently measured with Liquid Scintillation Counting to reverify the previously reported values used in this study to find updated gamma-ray branching ratio values.
A flowing-water target was irradiated with a 150 MeV/nucleon beam of78Kr at the National Superconducting Cyclotron Laboratory to produce77Kr and76Kr. Real-time gamma-imaging measurements revealed the ...mass transport of the krypton radioisotopes through the target-water processing, or “isotope harvesting”, system. The production rates were determined to be 2.7(1) × 10–4nuclei of76Kr and 1.18(6) × 10–2nuclei of77Kr formed per incident78Kr ion. Utilizing an off-gas processing line as part of the isotope harvesting system, a total of 7.2(1) MBq of76Kr and 19.1(6) MBq of77Kr were collected in cold traps. Through the decay, the daughter radionuclides76Br and77Br were generated and removed from the traps with an average efficiency of 77 ± 12%. Due to the differences in half-lives of76Kr and77Kr, it was possible to isolate a pure sample of76Br with 99.9% radionuclidic purity. The successful collection of krypton radioisotopes to generate76Br and77Br demonstrates the feasibility of gas-phase isotope harvesting from irradiated accelerator cooling-water. Larger-scale collections are planned for collecting by-product radionuclides from the Facility for Rare Isotope Beams.
A sample of 47Ca produced through isotope harvesting at the National Superconducting Cyclotron Laboratory was used to measure branching ratios of 7.17(5)%, 7.11(5)%, and 75.0(5)% for the 489.2, ...807.9, and 1297.1 keV characteristic gamma rays, respectively. Based on these updated branching ratios, the ground state to ground state 47Ca to 47Sc beta decay branching ratio has been indirectly measured as 17.7(5)% and the ground state to 1297.1 keV excited state as 82.2(5)%. These values represent a greatly increased precision for all five branching ratios compared to the currently accepted values (Burrows, 2007). The measurements presented here were made relative to the ingrown 47Sc daughter in a47Ca sample and the well-established 159.4 keV gamma-ray branching ratio and the half-life for the decay of 47Sc (Reher et al., 1986; Meadows and Mode, 1968; Mommsen et al., 1980). These measurements were supported by verifying that the half-lives measured from characteristic gamma-ray peaks over multiple spectra for both 47Ca and 47Sc were consistent with previously reported values. Additionally, the half-lives of both 47Ca and 47Sc were independently measured with Liquid Scintillation Counting to reverify the previously reported values used in this study to find updated gamma-ray branching ratio values.
•47Ca beta decay branching ratios determined.•Branching ratio for three highest intensity gamma-rays in 47Ca decay measured.•Precision in branching ratios improved by greater than a factor of 10.•47Ca collected via “isotope harvesting”.•Half-lives of 47Ca and 47Sc remeasured.
A sample of
Ca produced through isotope harvesting at the National Superconducting Cyclotron Laboratory was used to measure branching ratios of 7.17(5)%, 7.11(5)%, and 75.0(5)% for the 489.2, 807.9, ...and 1297.1 keV characteristic gamma rays, respectively. Based on these updated branching ratios, the ground state to ground state
Ca to
Sc beta decay branching ratio has been indirectly measured as 17.7(5)% and the ground state to 1297.1 keV excited state as 82.2(5)%. These values represent a greatly increased precision for all five branching ratios compared to the currently accepted values (Burrows, 2007). The measurements presented here were made relative to the ingrown
Sc daughter in a
Ca sample and the well-established 159.4 keV gamma-ray branching ratio and the half-life for the decay of
Sc (Reher et al., 1986; Meadows and Mode, 1968; Mommsen et al., 1980). These measurements were supported by verifying that the half-lives measured from characteristic gamma-ray peaks over multiple spectra for both
Ca and
Sc were consistent with previously reported values. Additionally, the half-lives of both
Ca and
Sc were independently measured with Liquid Scintillation Counting to reverify the previously reported values used in this study to find updated gamma-ray branching ratio values.
The quest to improve the quality of nuclear data, such as half-lives, transition yields, and reaction cross-sections, is a shared endeavor among various areas of nuclear science.
V is a vanadium ...isotope for which experimental data on neutron reaction cross-sections is needed. However, traditional isotope production techniques cannot produce
V with high enough isotopic purity for some of these measurements. "Isotope harvesting" at the Facility for Rare Isotope Beams (FRIB) is a new isotope production technique that could potentially yield
V with the necessary purity for such studies. In this case,
Cr would be collected and allowed to generate
V that can be separated from undecayed
Cr to yield highly pure
V. Thus, any protocol for producing pure
V via isotope harvesting would involve utilizing a separation technique that can effectively separate
Cr and
V. In this study, the radiotracers
Cr and
V were used to develop possible radiochemical separation methodologies, which can be translated to obtain high purity
V via this novel isotope production method. The developed protocols utilize either ion exchange or extraction chromatographic resins. Separations of
Cr and
V with AG 1-X8 anion exchange resin respectively resulted in recoveries of 95.6(26)% and 96.2(12)% with radionuclidic purities of 92(2)% and 99(1)%. An even more effective Cr and V separation was obtained with an extraction chromatographic resin (TRU resin) and 10 M HNO
loading solution. Here,
Cr and
V respectively had recoveries of 94.1(28)% and 96.2(13)% with high radionuclidic purities (100(2)% and 100(1)%) in small volumes (8.81(8) mL and 5.39(16) mL). This study suggests that, to maximize the yield and isotopic purity of
V, the best production protocol would involve utilizing two separations with TRU resin and 10 M HNO
to isolate
Cr and purify the generated
V.
Tungsten is a commonly used material at many heavy-ion beam facilities, and it often becomes activated due to interactions with a beam. Many of the activation products are useful in basic and applied ...sciences if they can be recovered efficiently. In order to develop the radiochemistry for harvesting group (IV) elements from irradiated tungsten, a heavy-ion beam containing 88Zr was embedded into a stack of tungsten foils at the National Superconducting Cyclotron Laboratory and a separation methodology was devised to recover the 88Zr. The foils were dissolved in 30% hydrogen peroxide, and the 88Zr was chemically purified from the tungsten matrix and from other co-implanted radionuclides (such as 85Sr and 88Y) using strong cation-exchange (AG MP-50) chromatographic resin in sulfuric acid media. The procedure provided 88Zr in approximately 60 mL 0.5 M sulfuric acid with no detectable radio-impurities. The overall recovery yield for 88Zr was (92.3 ± 1.2)%. This proof-of-concept experiment has facilitated the development of methodologies to harvest from tungsten and tungsten-alloy parts that are regularly irradiated at heavy-ion beam facilities.
•Proof-of-concept solid-phase isotope harvesting from tungsten collectors.•Solid-phase isotope harvesting for high recoveries of 88Zr from irradiated W foils.•Solid-phase isotope harvesting has higher recovery efficiency than aqueous-phase harvesting for 88Zr.•Radiochemical methods for extracting trace impurities from tungsten and tungsten-alloy parts were developed.
During routine operation of the Facility for Rare Isotope Beams (FRIB), radionuclides will accumulate in both the aqueous beam dump and along the beamline in the process of beam purification. These ...byproduct radionuclides, many of which are far from stability, can be collected and purified for use in other scientific applications in a process called isotope harvesting. In this work, the viability of 88Zr harvesting from solid components was investigated at the National Superconducting Cyclotron Laboratory. A secondary 88Zr beam was stopped in a series of collectors comprised of Al, Cu, W, and Au foils. This work details irradiation of the collector foils and the subsequent radiochemical processing to isolate the deposited 88Zr (and its daughter 88Y) from them. Total average recovery from the Al, Cu, and Au collector foils was (91.3 ± 8.9) % for 88Zr and (95.0 ± 5.8) % for 88Y, respectively, which is over three times higher recovery than in a previous aqueous-phase harvesting experiment. The utility of solid-phase isotope harvesting to access elements such as Zr that readily hydrolyze in near-neutral pH aqueous conditions has been demonstrated for application to harvesting from solid components at FRIB.
•Proof-of-concept solid-phase isotope harvesting demonstrated at the NSCL.•Solid-phase isotope harvesting for improved recoveries of Zr.•High recoveries of 88Zr and 88Y from Al, Cu, and Au foils irradiated with 88Zr beam.•Provides a framework for harvesting group IV elements from FRIB.
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