Developing a novel detector setup for the rapid superheavy element detection in the gas phase has been a current research topic for many scientists. The findings of our previous work showed that 1-(11-mercaptoundecyl)imidazole and 12-mercaptododecanoic acid self-assembled monolayers on Au-coated Si and glass chips are stable and effective materials for the Ir(IV) adsorption from HCl solutions [1]. As the next step, this paper reports the first attempt to sorb 152,153Er, 199-201At, and 173-176Ir radionuclides on thiolate-functionalized Au-coated Si detectors during online cyclotron-based experiments performed at the Cyclotron Institute at Texas A&M University using the AGGIE (Albert Ghiorso’s Gas-filled Ion Equipment) separator. A simple recoil transfer chamber equipped with four consecutive alpha-detectors was designed and used to thermalize nuclear reaction products and study their chemical behavior. The surfaces of three out of four detectors were Au-coated, two of which were functionalized with different thiol molecules. The design of the detector chamber allowed for an easy change of the detectors’ order. The detector position and the surface material were found to influence the sorption of the studied nuclides within the isothermal detector setup. The detector resolution stayed in the same order after the gold coating and the detector usage in online experiments.

The AGGIE gas-filled separator has been installed at the Cyclotron Institute at Texas A&M University and is now in routine use. Named Albert Ghiorso's Gas-filled Ion Equipment and formerly known as SASSY II and later SASSYER, the separator has a DvQhDv configuration and is currently used for nuclear reaction studies and online chemistry experiments. This manuscript describes the separator and experiments to measure its transmission, which was found to be approximate to 22% using the 164Dy(40Ar, xn)204-xPo reactions. Additionally, an investigation into AGGIE's ability to measure beam luminosity with a new, diamond detector was performed. The response of the diamond detector was characterized relative to the traditionally used silicon detector. The diamond detector was found to be overall suitable for luminosity measurements with a notable improvement in radiation hardness as evaluated based on the centroid, spectroscopic resolution and count rate of the implanting ions, thus minimizing potential for downtime while replacing detectors during an irradiation.

Isothermal vacuum adsorption chromatography (IVAC) in the molecular-flow regime offers the speed and chemical selectivity needed to study superheavy elements beyond flerovium (Fl, Z = 114). In this study, the GLACIER buffer gas cell and RF quadrupole combination was coupled with IVAC behind the gas-filled separator AGGIE for benchmark experiments with short-lived mercury radioisotopes 179Hg (t 1/2 = 1.05(3) s) and 178Hg (t 1/2 = 0.2665(24) s). GLACIER provided stable transport conditions over multiple days thereby enabling a clean chromatographic separation of Hg from less-volatile nuclear reaction byproducts on fused silica. These experiments validated the employed microscopic-kinetic transport model at zero surface coverage implemented in the form of a Monte Carlo simulation. The presented findings render this approach applicable to superheavy elements such as moscovium (Mc, Z = 115).

Terbium-149g ([Formula: see text] = 4.12 h) is of particular interest for targeted alpha therapy cancer treatment due to its ability to decay via both alpha and positron emission, making it a potential theranostic nuclide. Due to many challenges facing its production, there are limited facilities worldwide that have demonstrated the ability to produce this nuclide in quantities sufficient for medical research. Since the Cyclotron Institute at Texas A&M University is a specialized accelerator facility capable of accelerating a wide variety of ions, we are investigating production pathway options. One of the major challenges facing its production is the known co-production of the excited isomeric state, [Formula: see text]Tb ([Formula: see text] = 4.1 min). However, this state does not decay to the ground state of [Formula: see text]Tb, negating any potential contribution to its yield. Due to its short-half life, the cross section for the population of this state has never been measured. After calculating several potential reaction yields using predictive models, the reactions of [Formula: see text]Sm([Formula: see text]Li,xn)[Formula: see text]Tb were identified as candidates. Lithium-6 beams of varied energies between 45-65 MeV were impinged on enriched [Formula: see text]Sm, [Formula: see text]Sm, and [Formula: see text]Sm targets at the Cyclotron Institute at Texas A&M University, and the reaction products were measured immediately following irradiation using high-purity germanium detectors, enabling detection of both [Formula: see text]Tb and [Formula: see text]Tb. Cross sections for all nuclides produced in sufficient activity in these reactions were also measured and reported here. We conclude that the population of [Formula: see text]Tb is much preferred over population of the ground state for these [Formula: see text]Li-induced reactions, and it is necessary to explore other options for [Formula: see text]Tb production.

Terbium-149g (t1/2 = 4.12 h) is of particular interest for targeted alpha therapy cancer treatment due to its ability to decay via both alpha and positron emission, making it a potential theranostic nuclide. Due to many challenges facing its production, there are limited facilities worldwide that have demonstrated the ability to produce this nuclide in quantities sufficient for medical research. Since the Cyclotron Institute at Texas A&M University is a specialized accelerator facility capable of accelerating a wide variety of ions, we are investigating production pathway options. One of the major challenges facing its production is the known co-production of the excited isomeric state, 149mTb (t1/2 = 4.1 min). However, this state does not decay to the ground state of 149gTb, negating any potential contribution to its yield. Due to its short-half life, the cross section for the population of this state has never been measured. After calculating several potential reaction yields using predictive models, the reactions of 147-149Sm(6Li,xn)149Tb were identified as candidates. Lithium-6 beams of varied energies between 45-65 MeV were impinged on enriched 147Sm, 148Sm, and 149Sm targets at the Cyclotron Institute at Texas A&M University, and the reaction products were measured immediately following irradiation using high-purity germanium detectors, enabling detection of both 149mTb and 149gTb. Cross sections for all nuclides produced in sufficient activity in these reactions were also measured and reported here. We conclude that the population of 149mTb is much preferred over population of the ground state for these 6Li-induced reactions, and it is necessary to explore other options for 149gTb production.

Terbium-149g ( $$t_{1/2}$$ = 4.12 h) is of particular interest for targeted alpha therapy cancer treatment due to its ability to decay via both alpha and positron emission, making it a potential theranostic nuclide. Due to many challenges facing its production, there are limited facilities worldwide that have demonstrated the ability to produce this nuclide in quantities sufficient for medical research. Since the Cyclotron Institute at Texas A&M University is a specialized accelerator facility capable of accelerating a wide variety of ions, we are investigating production pathway options. One of the major challenges facing its production is the known co-production of the excited isomeric state, $$^{149\textrm{m}}$$ Tb ( $$t_{1/2}$$ = 4.1 min). However, this state does not decay to the ground state of $$^{149\textrm{g}}$$ Tb, negating any potential contribution to its yield. Due to its short-half life, the cross section for the population of this state has never been measured. After calculating several potential reaction yields using predictive models, the reactions of $$^{147-149}$$ Sm( $$^{6}$$ Li,xn) $$^{149}$$ Tb were identified as candidates. Lithium-6 beams of varied energies between 45-65 MeV were impinged on enriched $$^{147}$$ Sm, $$^{148}$$ Sm, and $$^{149}$$ Sm targets at the Cyclotron Institute at Texas A&M University, and the reaction products were measured immediately following irradiation using high-purity germanium detectors, enabling detection of both $$^{149\textrm{m}}$$ Tb and $$^{149\textrm{g}}$$ Tb. Cross sections for all nuclides produced in sufficient activity in these reactions were also measured and reported here. We conclude that the population of $$^{149\textrm{m}}$$ Tb is much preferred over population of the ground state for these $$^{6}$$ Li-induced reactions, and it is necessary to explore other options for $$^{149\textrm{g}}$$ Tb production.

Au-coated Si alpha-particle detectors have been widely used during the chemical characterization of superheavy elements that have been an area of great interest to scientists for decades. Further experiments are aimed at the functionalization of this type of detector to study the chemical properties of meitnerium. It is expected to be a member of the group 9 elements of the periodic table, and its chemical properties have not been studied before. In this study, self-assembled monolayers (SAMs) of 1-(11-mercaptoundecyl)imidazole (Im-C11-SH) and 12-mercaptododecanoic acid (MDDA) on 1 x 1 cm2 Au-coated Si and glass chips were prepared and characterized using several analytical and optical techniques: atomic force microscopy (AFM), nanoprojectile secondary ion mass spectrometry (NP-SIMS), X-ray photoelectron spectroscopy (XPS), ellipsometry, and instrumental neutron activation analysis (INAA). The coverage of Au-coated Si chips with Im-C11-SH SAMs was (99 +/- 6)%. NP-SIMS showed quantitative sorption of Rh(III) from an HCl medium, the coverage of Im-C11-SH SAMs with Rh(III) was (81.3 +/- 3.8)%. INAA showed quantitative sorption of Ir(IV) and illustrated that it can be adsorbed from a 5.4 mu M initial Ir(IV) solution in 0.55 M HCl on the Im-C11-SH and MDDA SAMs with a surface saturation of (77 +/- 12)% and (84 +/- 16)%, respectively.

Eutectic mixtures have been considered as alternative green solvents due to having characteristics similar to ionic liquids. Some of these solvents were reported to be hydrophobic and were able to extract metal ions from aqueous media through a liquid-liquid extraction process. In this work, the ability of a hydrophobic eutectic mixture composed of DL-menthol and lauric acid (ES-MLA) to extract In(III) and Tl(I, III) from hydrochloric acid media was investigated. The most promising results were obtained for Tl(III). The addition of bis(2-ethylhexyl) phosphoric acid (HDEHP) into ES-MLA was able to improve the extraction yields of In(III) and Tl(I) significantly, particularly at low acidity, but had a minor effect on Tl(III) extraction. Metal extraction decreases in the order Tl(III) > Tl(I) > In(III) for the entire HCl range studied in the case of pure ES-MLA and above 1 M HCl for the HDEHP + ES-MLA systems. A mathematical model to explain the metal extraction is presented. When added HDEHP diluents, the effect of the ES-MLA eutectic mixture and the conventional solvent kerosene on In(III) and Tl(III) extraction was also studied. It was observed that the kerosene-containing system was able to improve In(III) extraction at low acidity by two orders of magnitude while Tl(III) behavior in this acidity range was not affected. However, at high acid concentrations, the eutectic-based system shows advantageous behavior.

The alpha emitter astatine-211 (211At) is a promising candidate for cancer treatment based on Targeted Alpha (α) Therapy (TAT). A small number of facilities, distributed across the United States, are capable of accelerating α-particle beams to produce 211At. However, challenges remain regarding strategic methods for shipping 211At in a form adaptable to advanced radiochemistry reactions and other uses of the radioisotope. PURPOSE:Our method allows shipment of 211At in various quantities in a form convenient for further radiochemistry. PROCEDURES:For this study, a 3-octanone impregnated Amberchrom CG300M resin bed in a column cartridge was used to separate 211At from the bismuth matrix on site at the production accelerator (Texas A&M) in preparation for shipping. Aliquots of 6 M HNO3 containing up to ≈2.22 GBq of 211At from the dissolved target were successfully loaded and retained on columns. Exempt packages (<370 MBq) were shipped to a destination radiochemistry facility, University of Texas MD Anderson Cancer Center, in the form of a convenient air-dried column. Type A packages have been shipped overnight to University of Alabama at Birmingham. MAIN FINDINGS:Air-dried column hold times of various lengths did not inhibit simple and efficient recovery of 211At. Solution eluted from the column was sufficiently high in specific activity to successfully radiolabel a model compound, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline (1), with 211At. The method to prepare and ship 211At described in this manuscript has also been used to ship larger quantities of 211At a greater distance to University of Alabama at Birmingham. PRINCIPAL CONCLUSIONS:The successful proof of this method paves the way for the distribution of 211At from Texas A&M University to research institutions and clinical oncology centers in Texas and elsewhere. Use of this simple method at other facilities has the potential increase the overall availability of 211At for preclinical and clinical studies.

Astatine sorption by ion exchange resins from nitric acid media.

Astatine is one of the least chemically studied elements and its behavior in the presence of non-conventional solvents has not been investigated before. This work considers both hydrophobic ionic liquids and binary mixtures as alternatives to conventional solvents. The study is based on the extraction of astatine and bismuth (target material required to produce astatine) into imidazolium-based ionic liquid, and binary mixtures formed by active pharmaceuticals (ibuprofen, lidocaine) and a food-grade ingredient (methyl anthranilate). It is shown that both the ionic liquid and binary mixtures can successfully extract At from nitric acid media, but extraction of Bi into the ionic liquid is very inefficient, resulting in a good separation factor for these two elements in the entire studied acidity range. Extraction of At into binary mixtures is very efficient, having distribution ratio values as high as 1000, while the behavior of Bi under these conditions depends on the composition of the mixture. A mathematical model has been developed to fit both At and Bi experimental data and applied to determine corresponding thermodynamic extraction constants.

Systematic study of astatine (At) sorption on extraction chromatography resins from nitric acid media has been performed at Texas A&M University. This work covers commercially available resins such as LN, TK400, SR, TRU, and UTEVA. Acquiring an understanding of At behavior in up to 4 M HNO3 solutions is a key step to develop a rapid and reliable system for At separation and purification. The determined distribution coefficients are greater than 20 for all the resins studied, reaching 400 for TRU and UTEVA resins. The sorption uptake decreases in the order: TRU greater than or similar to UTEVA > TK400 greater than or similar to SR > LN. For each resin a thermodynamic model has been developed to suggest a possible mechanism of At sorption and corresponding sorption constants have been estimated. Literature data along with new results on bismuth (Bi) sorption by studied resins in nitric acid media have been reviewed and a mathematical model to describe its behavior has been suggested. A ratio of corresponding fit functions of At and Bi assigned to the same resin and acidity has been used to estimate separation factors of these elements. Only the TRU resin is not suitable for efficient At isolation from Bi, while the other four resins demonstrate promising results.

Background: Previously reported fusion-evaporation cross sections of residues in 45Sc-induced reactions with lanthanide targets are much smaller than 48Ca-induced reactions on the same targets. 44Ca is one proton removed from 45Sc and could be used to produce nuclei with a relative neutron content between those produced in the 45Sc-and 48Ca-induced reactions. Purpose: Several experiments worldwide have attempted to discover elements beyond the currently heaviest known element, oganesson (Z = 118). Due to a lack of appropriate targets, these efforts focused on projectiles other than 48Ca, which has been widely used for a number of successful element discovery experiments. The present study continues our previous work to understand the influence of various projectiles on the compound nu-cleus in fusion-evaporation reactions, and addresses the influence of target neutron number on fusion-evaporation cross sections. Methods: In experiments performed at the Cyclotron Institute at Texas A&M University, a beam of 44Ca6+ with an energy of ti 5 MeV/u was delivered by the K500 superconducting cyclotron to the Momentum Achromat Recoil Spectrometer (MARS). The 44Ca projectiles bombarded various isotopically enriched Gd targets in the MARS target chamber to create evaporation residues, which were spatially separated from unreacted projectiles by MARS and identified via their characteristic alpha-decay energies. Excitation functions for the reactions of 44Ca with 154,156,157,160Gd were measured at several projectile energies each. Results: The maximum 4n cross sections in the 44Ca +154,156,157,160Gd reactions were 0.038 +/- 0.008, 0.83 +/- 0.08, 3.8 +/- 0.2, and 3.0 +/- 0.5 mb, respectively. Production cross sections for the more neutron-rich targets were surprisingly constant even given the substantial changes in the difference in neutron binding energy and fission barrier of the compound nuclei. Conclusions: Collective enhancements to level density caused a reduction in compound nucleus survivability for all targets. While this effect was required to obtain good agreement between theoretical calculations and experimental data, it was not sufficient to explain the cross sections for the reaction with the most neutron -deficient target studied (154Gd). Instead, it appears that the difference in the fission barrier and neutron binding energy is the dominant factor affecting the survival of the compound nucleus in this case.

A detailed study of At and Bi extraction from nitric acid media into conventional solvents, namely 1-octanol and methyl anthranilate, has been performed. The analysis includes a mathematical modeling which allows the fitting of experimental data and determination of extraction constants of the two above mentioned elements. Also, this approach helped to estimate a stability constant of a weak AtO(NO3) complex along with thermodynamic constants describing the redox process of At species in the acidic solution and formation of an adduct of Bi in the presence of methyl anthranilate. The results of the fitting have been used to calculate corresponding separation factors of Bi and At as well. Moreover, a computational study has been performed to evaluate At interaction with the above mentioned solvents.

Ketones have been proven effective in extracting astatine(III) from aqueous solvents. Previous theoretical studies suggested a mechanism where the "sp2" lone pair on the carbonyl oxygen donates electron density into the π system of the AtO+ molecular cation to form a dative-type bond. In this study, co-extraction of NO3- as AtO(NO3)·(O═CR1R2) species into the organic phase appears to be a key factor. Adjusting the electronic properties of the ketone, by having an aryl group instead of an alkyl group in the alpha position of the ketone, increased the electron density on C═O, increased the bond strength between the ketone and AtO+, and in turn increased the extraction of 211At into the organic phase. Extraction with diketones shows dependence on the bridging distance between the two carbonyl moieties, where a C3 or longer bridge results in a 10-fold increase in extraction into the organic phase. DFT calculations show the longer bridge allows for the chelation of AtO(NO3) by either the second carbonyl or the phenyl ring.

Background: Previously reported fusion-evaporation cross sections of residues in $^{45}\mathrm{Sc}$-induced reactions with lanthanide targets are much smaller than $^{48}\mathrm{Ca}$-induced reactions on the same targets. $^{44}\mathrm{Ca}$ is one proton removed from $^{45}\mathrm{Sc}$ and could be used to produce nuclei with a relative neutron content between those produced in the $^{45}\text{Sc-}$ and $^{48}\mathrm{Ca}$-induced reactions.Purpose: Several experiments worldwide have attempted to discover elements beyond the currently heaviest known element, oganesson ($Z=118$). Due to a lack of appropriate targets, these efforts focused on projectiles other than $^{48}\mathrm{Ca}$, which has been widely used for a number of successful element discovery experiments. The present study continues our previous work to understand the influence of various projectiles on the compound nucleus in fusion-evaporation reactions, and addresses the influence of target neutron number on fusion-evaporation cross sections.Methods: In experiments performed at the Cyclotron Institute at Texas A University, a beam of $^{44}\mathrm{Ca}^{6+}$ with an energy of $\ensuremath{\approx}5\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}/u$ was delivered by the K500 superconducting cyclotron to the Momentum Achromat Recoil Spectrometer (MARS). The $^{44}\mathrm{Ca}$ projectiles bombarded various isotopically enriched Gd targets in the MARS target chamber to create evaporation residues, which were spatially separated from unreacted projectiles by MARS and identified via their characteristic $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{decay}$ energies. Excitation functions for the reactions of $^{44}\mathrm{Ca}$ with $^{154,156,157,160}\mathrm{Gd}$ were measured at several projectile energies each.Results: The maximum $4n$ cross sections in the $^{44}\mathrm{Ca}{+}^{154,156,157,160}\mathrm{Gd}$ reactions were $0.038\ifmmode\pm\else\textpm\fi{}0.008, 0.83\ifmmode\pm\else\textpm\fi{}0.08, 3.8\ifmmode\pm\else\textpm\fi{}0.2$, and $3.0\ifmmode\pm\else\textpm\fi{}0.5$ mb, respectively. Production cross sections for the more neutron-rich targets were surprisingly constant even given the substantial changes in the difference in neutron binding energy and fission barrier of the compound nuclei.Conclusions: Collective enhancements to level density caused a reduction in compound nucleus survivability for all targets. While this effect was required to obtain good agreement between theoretical calculations and experimental data, it was not sufficient to explain the cross sections for the reaction with the most neutron-deficient target studied $(^{154}\mathrm{Gd})$. Instead, it appears that the difference in the fission barrier and neutron binding energy is the dominant factor affecting the survival of the compound nucleus in this case.

Automation of irradiated bismuth target dissolution and astatine recovery from nitric acid media has been achieved at Texas A&M University. This process can be controlled remotely; it does not require any chemical treatment or evaporation of dissolution solution prior to the separation of above-mentioned elements on an extraction chromatography column, making the final product ready within 20 min. The accompanying radioimpurities have been identified and successfully separated from astatine, leading to greater than 99% radiopurity of the desired fractions. The system consists of only one pump and a set of LabVIEW controlled valves, and allows the connection of up to 10 different columns, providing the opportunity to prepare a variety of air dry columns, which can be different column geometries, containing astatine ready for further chemistry or shipment to desired facilities.

Non-monovalent state of cyclotron-produced thallium in the reaction of accelerated3He ions with gold.

The extraction and separation of iridium(IV) and rhodium(III) from hydrochloric acid solutions by a hydrophobic eutectic solvent composed of tetraheptylammonium chloride and decanoic acid have been studied for the first time. This eutectic solvent selectively extracts iridium(IV) over rhodium(III), the highest separation factor obtained is approximately 20. The effects of the main experimental factors (shaking time, the volume ratio of aqueous to organic phase, hydrochloric acid concentration, and the initial metal concentration in the aqueous phase) on the extraction behavior of iridium(IV) and rhodium(III) have been investigated. Ultraviolet-visible (UV-Vis) spectroscopy was applied to reveal the [IrCl6]2- complex to be a predominant species attributed to iridium(IV) extraction. To understand the underlying extraction mechanism, the initial iridium(IV) concentration in the aqueous phase has been varied and a corresponding mathematical model has been developed.