Bi Reaction Research Articles

Determination of the bremsstrahlung spectra by unfolding technique based on [formula omitted]Bi([formula omitted], xn) reactions

This work explores and describes the possibility of assessment of high energy bremsstrahlung spectrum, through the use of photonuclear reactions. Experimentally obtained values of saturation activities of various Bi isotopes, created by 209Bi(γ, xn) reactions in the 100 MeV bremsstrahlung beam were used in calculations. The photon spectrum is obtained by utilizing the unfolding techniques and cross sections data calculated by the TALYS 1.96 code. The experimental results were compared with the results obtained by Geant4 Monte Carlo simulation.

Looking through a new lens: Expressing the Ping Pong bi bi equation in terms of specificity constants

Several biotechnologically important enzymes catalyze reactions by the Ping Pong bi bi mechanism. Traditional kinetic equations for these enzymes contain several terms with combinations of three or four lumped parameters, making it difficult to relate the terms directly to the reaction mechanism. Further, the Ping Pong bi bi reaction mechanism is symmetrical in the forward and reverse directions, but the traditional equations are not mathematically symmetrical. In the present work, we express the Ping Pong bi bi kinetic equation in terms of specificity constants. Our equation is consistent with the traditional equations, but has several conceptual advantages. First, the terms of our equation contain two parameters at most, making it easier to relate the terms to specific features of the reaction mechanism. Second, our equation has only eight lumped parameters, so it has no redundant parameters; traditional equations have nine lumped parameters, such that one is redundant. Third, our equation is mathematically symmetrical, explicitly reflecting the symmetry of the Ping Pong bi bi reaction mechanism. We demonstrate how the parameters of our new equation can be estimated in classic initial rate experiments.

Rate equations for two enzyme-catalyzed Ping Pong bi bi reactions in series: General formulation for two reaction loops joined by a common vertex and deduction of a reaction loop selectivity factor

Interest is increasing in the application of lipases to catalyze sequential hydrolysis or transesterification reactions with diacids. In such systems, there are two Ping Pong bi bi reaction loops, with the free enzyme being the only enzyme form that is common to both loops. The modeling of such systems has not received much attention to date. The current work derives an expression for a reaction loop selectivity factor, denominated L, which is given by the ratio of the specificity constant of the enzyme for the first substrate of the second loop to the specificity constant for the first substrate of the first loop. The value of L is determined for two case studies using literature data. For the hydrolysis of diethyl adipate by Rhizopus arrhizus lipase, L is equal to 0.062, indicating that the specificity of this lipase for hydrolyzing diethyl adipate is much higher than that for hydrolyzing monoethyl adipate. For the CALB-catalyzed transesterification of diethyl azelate with 2-ethylhexan-1-ol, producing ethyl 2-ethylhexyl azelate as an intermediate and bis (2-ethylhexyl) azelate as the final product, L is 0.37, meaning that CALB prefers to transesterify diethyl azelate, rather than the intermediate ethyl 2-ethylhexyl azelate.

Assessment of the Second-Ionization Potential of Lawrencium: Investigating the End of the Actinide Series with a One-Atom-at-a-Time Gas-Phase Ion Chemistry Technique.

Experiments were performed at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron facility to investigate the electron-transfer reduction reaction of dipositive Lr (Z = 103) with O2 gas. Ions of 255Lr were produced in the fusion-evaporation reaction 209Bi(48Ca,2n) 255Lr and were studied with a novel gas-phase ion chemistry technique. The produced 255Lr2+ ions were trapped and O2 gas was introduced, such that the charge-exchange reaction to reduce 255Lr2+ to 255Lr1+ was observed and the reaction rate constant was determined to be k = 1.5(7) × 10-10 cm3/mol/s. The observation that this reaction proceeds establishes the lower limit on the second ionization potential of Lr to be 13.3(3) eV. This gives further support that the actinide series terminates with Lr. Additionally, this result can be used to better interpret the situation concerning the placement of Lu and Lr on the periodic table within the current framework of the actinide hypothesis. The success of this experimental approach now identifies unique opportunities for future gas-phase reaction studies on actinide and super heavy elements.

Excitation functions for 209Bi reactions induced by threshold to 50 MeV energy alpha particles

Excitation functions for 209Bi(α,2n)211At, 209Bi(α,3n)210At and 209Bi(α,4n)209At reactions were calculated using TALYS-1.95 nuclear code from threshold to 50 MeV by invoking suitable options for level densities, nucleon-nucleus optical model potentials and alpha optical model potentials. Statistical factors were used to verify the quality of matching between theoretical model calculations and the experimental data from the EXFOR database. The TTY of 211At calculated using the excitation function of 209Bi(a,2n)211At reaction is compared with existing experimental studies from literature The results of the present study are important for the validation of nuclear model approaches with increased predictive power for 209Bi(α,xn) reactions for the production of 211At.

Efficient removal of bismuth with supersoluble amorphous antimony acids: An insight into synthesis mechanism and Sb(V)-Bi(III) interaction behaviors

• Supersoluble amorphous antimony acid was prepared by controllable hydrolysis. • Phases and structures of A-SbA with different hydrolysis ratios were determined. • Hydrolysis and polymerization mechanism during A-SbA synthesis was investigated. • The maximum Bi(III) removal capacity by A-SbA can reach 300 mg g −1 . • Selective removal of Bi, Sb and As in H 2 SO 4 solution was achieved. The commonly used electrodeposition method for copper electrorefining electrolyte purification is actually suffered from the complicated process, expensive energy cost and the potential arsine hazard. This work synthesized a kind of submicro-sized amorphous antimonic acids (A-SbA) with ultrahigh solubilities in strong acid aqueous solution and evaluated their environment-friendly application in removing the problematic impurity bismuth (Bi). By controlling the hydrolysis ratio and aging time the crystalline structures and dissolution behaviors of A-SbA materials can be varied. The effects of hydrolysis ratio, aging time, temperature, acidity, initial Bi concentration and co-existing ions on Bi(III) removal efficiencies by A-SbA were systemically studied. The results show that the A-SbA prepared at a hydrolysis ratio of 1:2 without aging treatment has the highest solubility and the maximum Bi(III) removal capacity can reach 300.2 mg g −1 . The Sb(V)-Bi(III) reactions follow a pseudo-second-order kinetics model and the apparent activation energy of reaction process is calculated to be 32.14 kJ mol −1 . The Bi(III) removal efficiencies of over 99% can be achieved under the coexistence of Cu 2+ , Ni 2+ , Na + and Sb(III), while As(III,V) ions can also be partially precipitated together with Bi(III). This work gives an insight into the hydrolysis of antimony pentachloride and the polymerization of monomer HSb(OH) 6 as well as the Sb(V)-Bi(III)-As(III,V) interaction behaviors.

Identification of the New Isotope ^{244}Md.

In an experiment performed at Lawrence Berkeley National Laboratory's 88-inch cyclotron, the isotope ^{244}Md was produced in the ^{209}Bi(^{40}Ar,5n) reaction. Decay properties of ^{244}Md were measured at the focal plane of the Berkeley Gas-filled Separator, and the mass number assignment of A=244 was confirmed with the apparatus for the identification of nuclide A. The isotope ^{244}Md is reported to have one, possibly two, α-decaying states with α energies of 8.66(2) and 8.31(2)MeV and half-lives of 0.4_{-0.1}^{+0.4} and ∼6 s, respectively. Additionally, first evidence of the α decay of ^{236}Bk was observed and is reported.

New 209Bi photodisintegration data and physical criteria of data reliability

The well-known problem of noticeable disagreements between photoneutron cross sections from various experiments was discussed in detail for 209Bi. Data for partial photoneutron reactions cross sections obtained at Livermore (USA) using quasimonoenergetic annihilation photons and the method of neutron multiplicity sorting were analyzed using the objective physical criteria and the experimental-theoretical method for evaluation. Because of significant systematic uncertainties involved in the method for determining the neutron multiplicity, experimental data do not satisfy the criteria of reliability and differ noticeably from the evaluated data. The new experimental data for 209Bi (γ, in) reactions with i = 1–4 were obtained using quasimonochromatic laser Compton-scattering (LCS) γ-ray beams at the NewSUBARU synchrotron radiation facility and the novel technique of direct neutron-multiplicity sorting with a flat-efficiency detector. It was found that new σ(γ, 1n), σ (γ, 2n), and σ (γ, 3n) contradict noticeably to the Livermore data. It was shown that at the same time the new 209Bi photoneutron cross-sections are in good agreement with data evaluated using experimental-theoretical method and assuring the reliability of those.

Benchmarking FLUKA, PHITS, MCNPX, and MARS15 codes with product yields of 209Bi(p, x) reactions

The Monte Carlo particle transport codes, FLUKA, PHITS, MCNPX, and MARS15 were benchmarked by comparison to the measured product yields of proton-induced reactions on 209Bi from 43 to 100 MeV energy range. Two rounds of experiment were carried out to measure product yields of 209Bi(p, xn)207,206,205,204,203Po and 209Bi(p, pxn)207,206,205,204Bi reactions by using 100 MeV and 69 MeV proton beams. The targets were arranged in the stacks consisting of 209Bi activation foils, Al and Au monitor foils, and Pb plates as energy degraders. The predictive capability of the codes has been proven to be satisfactory from 55 to 100 MeV energy range. However, all codes are likely to underestimate the product yields of both investigated reactions over whole energy range and also the discrepancy between codes and measurements become larger at energy lower than 55 MeV.

The study of alpha particle induced reactions on bismuth-209 isotopes using computer code COMPLET

Calculations of the excitation function of 209Bi (α, n)212At, 209Bi (α, 2n)211At and 209Bi (α, 3n)210At reactions have been focussed on alpha induced reaction. Energy ranges of alpha particles were taken into computations as 10 MeV to 70 MeV. The objective of this study is to compare the computed results with the experimental data existing in the literature for each reactions. The calculated 209Bi(α,xn) reaction cross-sections were computed using computer code COMPLET and were then compared with the experimental nuclear reaction data obtained from EXFOR library in the literature. This calculated data was analyzed and interpreted with tabular and graphical descriptions. Good agreement was found between the experimental and theoretical data. The results were briefly discussed within the text of this research work.

Across barrier fission analysis of At⁎ isotopes formed in 3,4,6,8He+209Bi reactions

The fission decay mechanism of various 212,213,215,217At⁎ isotopes formed in tightly (3,4He) and loosely bound (6,8He) projectile induced reactions on 209Bi target, is studied within the framework of dynamical cluster-decay model (DCM), over a wide range of excitation energies spread across the Coulomb barrier. By optimizing appropriate neck-length parameter ΔR, the fission cross-sections are calculated for 212,213,215At⁎ compound nuclei (CN) at above barrier energies, where some experimental data is available. The DCM calculations are extended at below barrier region for these nuclei, and for one more reaction 8He+209Bi→217At⁎, using the systematics of 212,213,215At⁎ isotopes. The magnitude of fission cross-sections increase with the addition of neutrons in the He-projectile (or say in the At compound nucleus since the target nucleus of each reaction is same). To obtain better description of fission dynamics involved for neutron-deficient and neutron-rich He-induced reactions, the fragmentation potential and prefromation probability P0 of decaying fragments are analyzed along with corresponding barrier tunneling probability P. The fission fragment mass distributions are explored for all ‘At’ isotopes, and most probable fission fragments are identified. It has been observed that asymmetric fission forms the predominant decay mode for all isotopes, although a minor hump with very small preformation factor appears around symmetric fragments for lighter 212,213At⁎ nuclei. Finally, the N/Z dependence of fission cross-sections and most probable decaying fragments is explored in view of fragmentation structure and related cross-sectional yields.

Study and detection of relativistic Solar Neutrons at ground level with the Spherical Proportional Counter

A novel method of high energy solar neutron detection is proposed with the Spherical Proportional Counter (SPC), taking advantage of the 209Bi(n,f) reaction. This reaction, is considered as a standard for high energy neutron detection, due to large cross section values in the 100 MeV – 1 GeV energy interval, obtained in the n_TOF facility at CERN. A thin spherical shell of Bismuth will be situated in the large volume of the SPC, serving as target for high energy neutrons bombarding the detector, thus resulting in fission fragment emission. Detailed simulation of the 209Bi(n,f) reaction with the INCL++ model, coupled with the ABLA07 de–excitation code is performed (cross section, mass & atomic number distribution, kinetic energy per fragment) in the 100 MeV – 10 GeV energy interval, together with SRIM for the fragments’ projected range in 209Bi. Experimental data from a 252Cf source are obtained, in order to validate the SPC’s efficiency in fission fragment detection. Calculations for the expected reactions in the 209Bi shell have been performed in different atmospheric depths (700 & 1000 g/cm2), and various spherical detector radii.

Origins of Incomplete Fusion Products and the Suppression of Complete Fusion in Reactions of ^{7}Li.

Above-barrier complete fusion involving nuclides with low binding energy is typically suppressed by 30%. The mechanism that causes this suppression, and produces the associated incomplete fusion products, is controversial. We have developed a new experimental approach to investigate the mechanisms that produce incomplete fusion products, combining singles and coincidence measurements of light fragments and heavy residues in ^{7}Li+^{209}Bi reactions. For polonium isotopes, the dominant incomplete fusion product, only a small fraction can be explained by projectile breakup followed by capture: the dominant mechanism is triton cluster transfer. Suppression of complete fusion is therefore primarily a consequence of clustering in weakly bound nuclei rather than their breakup prior to reaching the fusion barrier. This implies that suppression of complete fusion will occur in reactions of nuclides where strong clustering is present.

Increased Uptake of At-211 in Thyroid Gland by the Preparation with Ascorbic Acid for Targeted Alpha Therapy of Thyroid Cancer

Astatine-211 (211At) is an alpha-emitting radionuclide suitable for targeted alpha therapy. Because At is a heavier homolog of iodine, astatide ion (At-) is expected to be applied to the treatment of thyroid cancer. In this study, 211At was treated by ascorbic acid (AA) as reducing agent to prepare At-. We aimed to evaluate the uptake change in the thyroid after the preparation of 211At solutions with AA and demonstrate the treatment effect in the differentiated thyroid cancer xenograft mice. Astatine-211 was produced in the 209Bi(α, 2n) reaction and supplied through Shortlived RI Supply Platform. Produced 211At was then separated from the target materials by a dry distillation method and dissolved in pure water. The aliquot of 211At solution was mixed with 1% AA solution to prepare At-. The radiochemical yield was checked by radio-TLC. The crude 211At solution or 211At with AA solution was administered to normal rats (n=3 for both solution) through tail vein under isoflurane anesthesia. In vivo imaging of 211At in the normal rats was then carried out using a gamma camera at 0.5, 3, 6 and 24 hrs after administration. The 211At solution with AA was also administered to mice with implanted K1 cells (human papillary thyroid carcinoma) expressing sodium iodide symporter (NIS). Mice were divided into 4 groups according to the injected dose [1 MBq (n=6), 0.4 MBq (n=6), 0.1 MBq (n=6), control (n=6)]. Distribution of 211At administered in the mice was investigated at 3 and 24 hrs after administration by the gamma camera. The radiochemical yield of At- checked by radio-TLC increased from approximately 20% to 90% after treatment of the crude 211At solution with AA. In vivo imaging of 211At in the normal rats showed high uptakes in the thyroid, the stomach, and the bladder. Uptake of At with AA in thyroid gland was 2–3 times higher compared to crude 211At solution. In the xenograft mice, there was a stable accumulation in the thyroid tumor at 3 and 24 hrs post administration (23 ± 11 %ID and 13 ± 7 %ID, respectively). Tumor growth was immediately inhibited after administration of 211At in a dose-dependent manner. Suppression of tumor growth was maintained until 17, 31, and 41 days after administration of 211At in 0.1, 0.4, and 1 MBq groups, respectively. Uptake of 211At can be enhanced in the normal thyroid by increasing the radiochemical purity of At-. The administered 211At showed good treatment effect in thyroid cancer xenograft, suggesting that 211At solution with AA is promising for the targeted alpha therapy for the thyroid cancer.

Puzzle of Complete Fusion Suppression in Weakly Bound Nuclei: A Trojan Horse Effect?

Experimental studies of nuclear collisions involving light weakly bound nuclei show a systematic suppression of the complete fusion cross section by ∼30% with respect to the expectation for tightly bound nuclei, at energies above the Coulomb barrier. Although it is widely accepted that the phenomenon is related to the weak binding of these nuclei, the origin of this suppression is not fully understood. Here, we present a novel approach that provides the complete fusion for weakly bound nuclei and relates its suppression to the competition between the different mechanisms contributing to the reaction cross section. The method is applied to the ^{6,7}Li+^{209}Bi reactions, where we find that the suppression of complete fusion is mostly caused by the flux associated with nonelastic breakup modes, such as the partial capture of the projectile (incomplete fusion), whereas the elastic breakup mode is found to play a minor role. Finally, we demonstrate that the large α yields observed in these reactions can be naturally explained as a consequence of a Trojan Horse mechanism.

Does Compound Nucleus remember its Isospin- An Evidence from the Fission Widths

We present an evidence of isospin effects in nuclear fission by comparing the fission widths for reactions involving different isospin states of the same compound nucleus (CN). Yadrovsky [1] suggested this possibility in 1975. Yadrovsky obtained the fission widths for two reaction data sets, namely 206Pb(α,f) and 209Bi(p,f), both leading to same CN, and concluded that “a nucleus remembers the isospin value of the nuclear states leading to fission”. We obtain the fission decay widths for both the T0 + ½ and T0 − ½ states of CN by using two appropriate reaction data sets. We then compare the fission widths for the two isospin states of CN. More specifically, we have chosen the combination of 206Pb(α,f) and 209Bi(p,f) same as presented in Yadrovsky’s paper [1] in this study. A significant difference between the ratios of fission decay widths to total decay widths for different isospin values suggests that isospin plays an important role in fission.

Dynamics of complete and incomplete fusion of 6,7Li, 15N and 16O with a 209Bi target

The dynamics of complete and incomplete fusion of 6,7Li, 15N and 16O with a common target (209Bi) around the Coulomb barrier are analyzed within the context of the coupled channel formulation and the energy dependent Woods-Saxon potential (EDWSP) model. The calculated results are compared with experimental fusion cross-sections and it has been shown that complete fusion (CF) data of weakly bound projectile with a heavy target (209Bi) gets suppressed at above barrier energies. In the case of the 6Li + 209Bi (7Li + 209Bi) reaction, the CF data at above barrier energies is reduced by 34% (26%) with reference to the expectations of the coupled channel approach. However, the theoretical estimations due to the EDWSP model can minimize the suppression factor by 9% with respect to the reported value and consequently the portion of above barrier CF cross-section data of 6Li + 209Bi (7Li + 209Bi) reaction is suppressed by 25% (17%) when compared with the present model calculations. This fusion inhibition can be correlated with the low breakup threshold of projectile which in turn breaks up into two fragments in the entrance channel prior to fusion barrier. The total fusion (TF) data, which is sum of complete fusion (CF) data and incomplete fusion (ICF) data, is not suppressed when compared with the predictions of the theoretical approaches and thus breakup channel has very little influence on the total fusion cross-sections. Although the breakup fragments appeared in both reactions, the enhanced suppression effects observed for the lighter projectile can be correlated with its low binding energy associated with the $\alpha$ -breakup channel. Further the outcomes of the EDWSP model reasonably explained the ICF contribution appeared in the fusion of 6,7Li + 209Bi reactions. In contrast to this, the observed fusion dynamics of 15N + 209Bi and 16O + 209Bi reactions, wherein the collective excitations such as two phonon, three phonon vibrational states contribute to produce below barrier fusion enhancement, has been adequately explored by the adopted models, and henceforth ensures the stability of well bound nuclei against breakup effects.

Measurements of cross sections for the 209Bi(n, 4n) reaction by using high energy neutrons with continuous energy spectra

We measured 209 Bi(n, 4n) cross sections at neutron energies E n = 29.8 ± 1.8 MeV and E n = 34.8 ± 1.8 MeV. Bismuth oxide samples were irradiated with the neutrons produced by impinging 30, 35 and 40 MeV proton beams on a 1.05 cm thick beryllium target, where the proton beams were from the MC-50 Cyclotron of Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux for each proton beam energy E p , Φ E p ( E n ), has a broad spectrum with respect to E n . By taking the difference in the neutron fluxes, the difference spectra, Φ 40 ( E n ) −Φ 35 ( E n ) and Φ 35 ( E n ) −Φ 30 ( E n ), are obatined and found to be peaked at E n = 29.8 and 34.8 MeV, respectively, with a width of about 3.6 MeV. By making use of this observation and employing the TENDL-2009 library we could extract the 209 Bi(n, 4n) 206 Bi cross sections at the aforementioned neutron energies.

The cross sections and energy spectra of the particle emission in proton induced reaction on 204,206,207,208Pb and 209Bi

All cross sections of proton induced reactions, angular distributions, energy spectra and double differential cross sections of neutron, proton, deuteron, triton, helium and alpha-particle emissions for p+ 204,206,207,208 Pb, 209 Bi reactions are consistently calculated and analyzed at incident proton energies below 200 MeV. The optical model, the distorted wave Born approximation theory, the unified Hauser-Feshbach and exciton model which includes the improved Iwamoto-Harada model are used. Theoretically calculated results are compared with the existing experimental data.

Analysis of complete, incomplete and total fusion data of 9Be +169Tm, 187Re, 209Bi reactions

We have analyzed the incomplete fusion (ICF), complete fusion (CF) and total fusion (TF) excitation functions for reactions induced by [Formula: see text] on [Formula: see text], [Formula: see text] and [Formula: see text] targets at near barrier energies using Wong’s formula in conjunction with the energy dependent Woods–Saxon potential. A phenomenological selection function is proposed to separate out the contribution of ICF and CF cross-sections in TF cross-section. The variation of relative contribution of ICF and CF in TF with respect to incident beam energy is very well reproduced through this approach.