Evaporation Residues Research Articles

Survival probability of Selenium-induced fusion reactions

In this paper, we investigated every potential scenario for selenium-induced heavy ion fusion reactions using astatine isotopes as the target. In this context, we examined [Formula: see text]Se projectiles and [Formula: see text]At targets having longer half-lives of comprising 21 fusion reactions for the synthesis of superheavy element [Formula: see text]. We assessed fusion cross-sections ([Formula: see text]), compound nucleus formation probability ([Formula: see text]), and survival probability ([Formula: see text]) for [Formula: see text]Se projectiles on [Formula: see text]At targets. The evaporation residue cross-sections ([Formula: see text]) is found to be larger for the fusion reaction of [Formula: see text]At of about 14.1[Formula: see text]fb. Hence, these striking results are useful in the synthesis of superheavy element [Formula: see text].

Possibility to synthesize $Z = 119$ superheavy nuclei with $Z>$ 20 projectiles

Abstract We employed the dinuclear system (DNS) model combined with statistical model to calculate the evaporation residue cross sections for the reaction systems $^{48}$Ca + $^{243}$Am, $^{48}$Ca + $^{248}$Cm, and $^{48}$Ca + $^{249}$Bk. The theoretical results successfully reproduced the experimental trends in the 3$n$ and 4$n$ evaporation channels of these reaction systems. In order to synthesize the new element $Z = 119$, we predicted the evaporation residue cross sections for three reaction systems ($^{54}$Cr + $^{243}$Am, $^{51}$V + $^{248}$Cm, and $^{50}$Ti + $^{249}$Bk) to select the most promising projectile-target combinations. We also noted that the maximum cross sections predicted by our model and other methods appear to be below the detection limits of current experimental facilities, given the projectile-target combinations feasible under current experimental conditions. Therefore, synthesizing superheavy nuclei with $Z = 119$ will require improvements in beam intensity, detection techniques, and effective separation methods.

Effect of evaporation temperature on evaporative residue properties of waterborne polyurethane modified emulsified asphalt

Abstract In recent years, waterborne polyurethane (WPU) modified emulsified asphalt has attracted much attention. The conventional property of WPU-modified emulsified asphalt (WPU-MEA) is usually measured by using the evaporative residue obtained at high temperatures. In this work, WPU-MEA was prepared and the influence of evaporative temperature on the conventional performances (softening point, penetration, ductility) of the residue of WPU-MEA was investigated. Fourier Transform Infrared Spectroscopy (FTIR) and Fluorescence microscope (FM) were used to analyze the chemical structure and morphology of the evaporative residues. It was found that the evaporation dehydration temperature has a significant influence on the property of the evaporation residue of WPU-MEA. The evaporative residue performance of WPU modified asphalt was better at an evaporation temperature of 110°C, and the three conventional properties were significantly improved. Upon increasing the evaporation temperature, the conventional properties of WPU-MEA continue to decrease. As the evaporation temperature is 190°C, the conventional property of the residue is close to that of unmodified emulsified asphalt. Considering the performance index of WPU-MEA, the optimal evaporation temperature should be determined in the characterization of residue performance. This study has a guiding significance for the development of polyurethane-modified asphalt materials.

Bayesian uncertainty quantification for synthesizing superheavy elements

To improve the theoretical prediction power for synthesizing superheavy elements beyond Og, a Bayesian uncertainty quantification method is employed to evaluate the uncertainty of the calculated evaporation residue cross sections (ERCS) for the first time. The key parameters of the dinuclear system model (DNS-sysu), such as the diffusion parameter a, the damping factor Ed, and the level-density parameter ratio af/an are systematically constrained by the Bayesian analysis of recent ERCS data. One intriguing behaviour is shown that the optimal incident energies (OIE) corresponding to the largest ERCS weakly depend on the fission process. We also find that these parameters are strongly correlated and the uncertainty propagation considering the parameters independently is not reasonable. The 2σ confidence level of posterior distributions for a=0.586−0.002+0.002 fm, Ed=25.65−3.41+3.43 MeV, and af/an=1.081−0.021+0.021 are obtained. Furthermore, the confidence levels of the ERCS and OIE for synthesizing Z = 119 via the reactions Cr54+243Am, Ti50+249Bk, and V51+248Cm are predicted. This work sets the stage for future analyses to explore the OIE and reaction systems for the synthesis of superheavy elements.

A study on the synthesis of superheavy element Mc (Z = 115) using lead, bismuth and actinide targets

The evaporation residue cross sections in synthesizing isotopes of superheavy element Mc (Z = 115) by the hot fusion reactions 48Ca+241,243Am→289,291Mc, 45Sc+240,242,244Pu→285,287,289Mc, 50Ti+236,237Np→286,287Mc, 51V+238U→289Mc, 36S+253Es→289Mc, 46K+248Cm→294Mc, and by the cold fusion reactions 78As+208Pb→286Mc, 76Ge+209Bi→285Mc have been systematically investigated using the phenomenological model for production cross section. We have predicted the most effective projectile-target combinations for synthesizing Mc isotopes among these reactions. Our result shows that the 3n- channel cross section is larger for the reaction 48Ca+243Am→291Mc, and the 4n- channel cross section is larger for the reaction 46K+248Cm→294Mc. This study also examines the effect of the use of mass values and shell corrections by the Möller and Warsaw groups. Using our predicted combinations and the cross section values at a range of excitation energies, we hope these isotopes of Mc can be synthesized in near-future experiments.

Small cross section of the synthesis of darmstadtium in the Ca48+Th232 reaction

The smallness of the cross section of evaporation residues formed in the hot fusion reaction Ca48+Th232 is analyzed by the dinuclear system model (DNS). The capture probability has been calculated by solving the dynamical equations of motion for the relative distance between the centers of mass of the DNS nuclei. Fusion of nuclei is considered as evolution of the DNS to a stable compound nucleus. The fusion probability has a bell-like shape and quasifission is one of reasons causing smallness of the yield of the evaporation residues products. Another reason is the decrease of the fission barrier for the isotopes Dm275–285 related with the shell effects in the neutron structure. The agreement of the theoretical results obtained for the yield of the evaporation residues with the experimental data measured in the Factory of Superheavy Elements of Joint Institute for Nuclear Research is well. Published by the American Physical Society 2024

E-ΔE detection module of DGFRS-2 setup

Thе paper describes a new E-ΔE detection module which includes a position-sensitive double-sided strip detector (DSSD) and a low-pressure pentane-filled ΔE chamber for detection of Evaporation Residues (ERs) in complete fusion reactions. The goal is to synthesize superheavy isotopes at the new DC-280 (Dubna Cyclotron) cyclotron of the Joint Institute for Nuclear Research (JINR). With the 48Ca ion beam intensity of about 5–7 pμA (particle micro ampere) and the ΔE counter count rate of approximately 104 sec−1, we observe a decrease in the overall registration efficiency of the gas ΔE counter. The paper proposes a solution to this problem: introduction of an additional negatively biased electrode, which results in the stabilization of the ΔE detector operation.

70Zn-induced fusion reactions for synthesis of superheavy element Z=120

In this work, we delved into the intriguing realm of nuclear physics by investigating fusion reactions initiated by [Formula: see text]Zn projectiles colliding with various stable isotopes of thorium nuclei, including [Formula: see text]Th. Our primary objective was the synthesis of the superheavy element [Formula: see text]. To achieve this, we employed an advanced statistical model to evaluate the evaporation residue cross-sections. Remarkably, we observed that the fusion reaction between [Formula: see text]Zn and [Formula: see text]Th exhibited the highest evaporation residue cross-sections, reaching a peak value. Furthermore, the 3n channel within this fusion reaction yielded substantially larger evaporation cross-sections, with a notable value of 0.89 picobarns. The predicted cross-sections fall within the measurable range, making them highly valuable for experimental endeavors aimed at synthesizing the superheavy element [Formula: see text]. This research not only contributes to our understanding of nuclear reactions but also holds promise for expanding our knowledge of the heaviest elements in the periodic table, potentially opening new frontiers in nuclear science.

Luminescent Solar Concentrator with Advanced Structure for Reabsorption Loss Suppression and Synergistic Energy Harvesting

AbstractAs large‐area and optically transparent photon harvesting devices, luminescent solar concentrators (LSCs) are promising candidates for building‐integrated photovoltaics owing to their high transmittance and resistance to shadowing effects existing in solar cells. Up to now, there are still many challenges in the practical application of LSCs: 1) Reabsorption loss is inevitable during photoluminescence transmission due to indirect illumination of solar cells in LSC system. 2) Satisfactory energy harvesting cannot be achieved in rainy conditions due to the substantial attenuation of the incident light intensity. 3) Evaporation residue on the surface of LSCs leads to device performance degradation. Pioneering researches and feasible strategies for reabsorption loss suppression, energy harvesting in rainy days as well as self‐cleaning property are still lacking demonstration. In this work, reabsorption loss is suppressed based on advanced structural LSCs with universally applicable optical spacer layer. Then the integrated LSCs with droplet‐based electricity generator (DEG) are proposed for the first time. Such DEG‐LSCs not only realize synergistic harvesting of solar and raindrop energy, but also possess self‐cleaning properties. Finally, a self‐powered temperature and humidity sensing system is designed and demonstrated to provide feasible ideas for the practical application of DEG‐LSCs in self‐powered intelligent buildings.

Fabricating functionalized carbon nitride using leachate evaporation residue and its adsorptive application

Herein, we report a leachate evaporation residue (LER) functionalized carbon nitride (g-C3N4) material (RCNs) through a facile one-step calcination strategy, which simultaneously realizes the resource utilization of LER and its application in environmental remediation. The alkali metals (K, Na) and alkaline earth metals (Ca, Mg) in the LER were confirmed to be successfully anchored within the tri-s-triazine ring units or interlayer. LER inorganic salts cause the C-N = C bonds in RCNs to break and form cyanide groups, while organic compounds introduce aromatic rings and C = O/C-O functional groups into RCNs. These structural deformations in RCNs provides more adsorption sites for methylene blue (MB). Maximum RCNs adsorption capacity for MB increased to 1166.7 mg/g, which exceeded most of the carbon-based adsorbent materials. Meanwhile, RCNs were comprehensively evaluated as excellent selective adsorption, recycling, and practical utilization feasibility for MB. The adsorption mechanism has been systematically confirmed and attributed to fortified electrostatic interaction, hydrogen bonding, cation-π, and π-π interactions. This work provides a feasible strategy for modifying carbon nitride with high-value organic–inorganic composite waste.

Observation of suppression of heavy-ion fusion by slow quasifission

The formation of superheavy elements (SHEs) by nuclear fusion can be conceptually divided into two steps: capture, and compound nucleus formation. Once captured, the two nuclei may reseparate before fusing to form a compact compound nucleus. This outcome is called quasifission. Fusion-fission, in many cases, leads to reactions outcomes inseparable from quasifission. Evaporation residue (ER) measurements are therefore the most reliable, direct experimental signature of fusion. ER cross section measurements forming the same compound nucleus, 220Th, using 16O, 40Ar, 48Ca, 82Se and 124Sn-induced reactions [1–4] revealed [1] that fusion was severely suppressed for the more symmetric reactions relative to the 16O-induced reaction. Here two new reactions forming 220Th using 28Si, 34S projectiles provide conclusive evidence that the ER cross section is exponentially suppressed as a function of ZpZt. The fission characteristics show no mass-angle correlation, demonstrating that here ER cross sections are suppressed by slow quasifission.

The superheavy nuclei: Fusion-evaporation reactions

The synthesis of superheavy elements beyond the oganesson (Og, Z = 118) remains one of the actual topics in nuclear physics. For this purpose, the fusion reactions with projectiles heavier than 48Ca, which were successfully implied for the synthesis of the heaviest elements, and actinide targets have to be used. However, empirical knowledge on such reactions is almost absent. In this work, the experimental cross sections of the “hot”, “cold”, and 48Ca+actinide reactions were analyzed to reveal their differences in the three steps of the fusion-evaporation process. The evaporation residue cross sections represented as a function of the mean fissility parameter show the hitherto unnoticed difference between the “hot” and “cold” fusion reactions, which is in agreement with nuclear reaction dynamic studies. Based on the newly suggested systematics, the evaporation residue cross sections for the 50Ti, 51V, 54Cr, 58Fe and 64Ni-induced reactions with actinide targets were estimated within the two different empirical approaches.

Preparation and application of rubber modified emulsified asphalt

Processing waste tyres into crumb rubber (CR) powder as an asphalt modifier is an efficient solution to solid waste management. It has been found to have significant environmental and economic benefits. However, current research on rubber modified asphalt (CRMA) mainly concentrates on improving the binder properties, overlooking the systematic research on rubber modified emulsified asphalt (E-CRMA). Thus, this study investigates the preparation and development of E-CRMA technology. To achieve rubber asphalt with low viscosity, excellent uniformity, and emulsification, CR was first activated with waste oil. Cracking catalyst was later added during the preparation process of CRMA. A controlled variable method was employed to examine the impact of preparation temperature, preparation time, CR particle size, and dosage on the production of CRMA that is suitable for emulsification. The optimal conditions for preparing E-CRMA were identified as 18 wt% 80 mesh CR mixed with asphalt, stirred at 220 ℃ for 75 min. Additionally, the impact of emulsifier and stabilizer types and quantities on E-CRMA performance were examined. The emulsification conditions of 3% medium split emulsifier and 0.77% compound organic/inorganic stabilizer were identified. The study compared and analyzed the storage stability, basic physical properties of evaporative residue, and rheological properties of E-CRMA, base emulsified asphalt (EA), SBS/SBR modified emulsified asphalt at high and low temperatures. Direct shear and tensile tests were conducted to determine the optimal amount of E-CRMA for use as an adhesive and sealing layer, which was found to be 0.8 kg/m2. The study reveals that E-CRMA possesses comparable shear and tensile properties to E-SBRMA and E-SBSMA at the optimal sprinkling amount. Moreover, the water seepage resistance of E-CRMA has shown an increase of 80%, 66.7%, 28.6%, and 21.9% over that of no sealing layer, EA, E-SBSMA, and E-SBRMA, correspondingly. The E-CRMA produced in this study broadened the application scope of CRMA, filled the gap in the research area of E-CRMA applications. In the future, it is expected to be applied to the bonding between road surface layers and the lower sealing layer between the surface layer and the base layer.

Systematic study of fusion suppression and its dependency on projectile breakup threshold energy

Measurements of the excitation function (EF) of the observed evaporation residues (ERs) populated in the 20Ne + 93Nb reaction at E lab ≈ 91−145 MeV are carried out to explore the systematic of fusion suppression and its dependency on projectile breakup threshold energy, by employing the offline γ-ray detection method. The EF of the observed ERs populated through complete and/or incomplete fusion processes are analysed in the framework of statistical mode code PACE4. The fusion function, derived from the experimentally measured fusion cross section data, is compared with the universal fusion function (UFF) to estimate the degree of fusion incompleteness. Based on the observed results, an empirical formula is proposed to interrelate the degree of fusion suppression and breakup threshold energy of the incident projectile.

Comprehension of breakup fusion reactions using forward recoil range distribution measurements

To understand the break-up fusion reaction dynamics, the forward recoil range distribution (FRRD) measurements of 12C + 165Ho system at the incident projectile energy of ≈ 88 MeV has been performed. The recoil catcher activation technique followed by the off-line gamma ray spectroscopy was implemented. It is observed that the FRRD measurements of the evaporation residues (ERs) populated via xn and pxn channels have a single Guassian peak at large cumulative thickness. This is attributed to complete momentum transfer from the projectile to the target nucleus. However, in case of the FRRD measurements of the ERs populated via αxn, αpxn and 2αxn emitting channels, in addition to peak corresponding to complete momentum transfer, the Gaussian peaks at lower cumulative thicknesses are also observed. This is accredited to the breakup fusion. Moreover, the effect of projectile breakup on complete fusion cross section is also studied. The suppression in fusion cross section is observed when compared with the universal fusion function, thus indicating the breakup probability of 12C projectile.

Entrance channel dependence of quasi fission in reactions leading to 206Po compound nucleus

The evaporation residue (ER) cross sections for the reaction F19+187Re→206Po⁎ are measured, in the excitation energy range of 86.1 to 118.4 MeV. The measured cross sections are compared with that of 30Si + 176Yb reaction populating the same compound nucleus. Theoretical calculations are performed using the coupled - channels calculations for the capture cross sections and statistical model calculations for the ER cross sections. The dependence of quasi fission on entrance channel parameters such as charge product (Z1Z2), mass asymmetry (α), target deformation (β2) and effective fissility (χeff) are studied.

Evaporation residue cross-section measurements for 30Si+142Ce system

Evaporation residue (ER) cross-sections were measured for 30Si+142Ce reaction at laboratory energies in the range of 105 - 132 MeV using the HYbrid Recoil mass Analyzer (HYRA) at IUAC, New Delhi. The transmission efficiency of the HYRA was estimated using the calibration reaction 28Si+142Ce. Sub-barrier fusion enhancement was observed when compared with the one-dimensional barrier penetration model predictions for the present system. To explore the phenomena responsible for sub-barrier fusion enhancement, coupled-channels calculations were performed using the CCFULL code. The effect of couplings and the role of positive Q-value neutron transfer (PQNT) channels on sub-barrier fusion cross-sections were investigated. Coupled-channels calculations were able to reproduce the data by including the coupling in both projectile and target nucleus along with two neutron-transfer channels having positive Q-value. The measured ER cross-sections were compared with the nearby systems to explore the role of deformation of the colliding nuclei.

Supported liquid extraction combined with liquid chromatography tandem mass spectrometry for the quantitative analysis of a TLR7 agonist imiquimod LFX453 in plasma at low picograms per milliliter: Method validation and its application to a pharmacokinetic study in minipig.

Sample preparation is essential for low-level compound determination. In the present work, supported liquid extraction (SLE) was used as sample preparation for the low-level determination of a new TLR7 agonist imiquimod compound, LFX453. Samples were extracted on ISOLUTE® SLE 96-well plates using tert-butyl-methyl ether followed by evaporation and dry residue reconstitution with 150 μl of a mixture of 0.1% formic acid in acetonitrile-water (50/50, v/v). Samples were eluted using a flow rate of 0.750 ml/min on a C18 column (50 ×2.1mm, 2.7μm) with a mobile phase consisting of 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B). Tandem mass spectrometry was used to analyze the samples in positive mode. The method run time was 6.5min, and the low limit of quantification was 1.00 pg/ml with 0.100 ml of minipig plasma. Intra-run and inter-run precision and accuracy were within the acceptance criteria at four concentration levels over a concentration ranging from 1.00 to 200 pg/ml. There was no matrix effect and recovery, three freeze-thaw cycles and incurred samples reanalysis were validated. The method was successfully applied for measuring LFX453 in minipig plasma after application on minipig skin.

Investigating the influence of input angular momentum on independence hypothesis in heavy-ion induced fusion reactions

The experimental verification of compound nucleus theory has successfully been performed for light ion induced reactions using proton and α-particle beams on different targets. However, such studies using the heavy ion beams are scarce due to the complex nature of heavy ion interaction process. The present work is an attempt to validate the Bohr's independent hypothesis using heavy ion beam of 18O beam on 159Tb targets and 12C on 165Ho targets, forming the same compound nucleus 177Ta. A channel wise analysis of cross section data for evaporation residues produced in 18O+159Tb and 12C+165Ho systems has been performed within the framework of statistical model code PACE4 and found to reasonably agree with the experimental data. Further, a comparison of reaction cross section data for the same evaporation residues produced in the two different systems has been found to follow Bohr's compound nucleus hypothesis at relatively higher excitation energies. However, at relatively lower excitation energies, a significant deviation in the measured cross section data of the same residues in the above mentioned systems have been observed and is attributed to the discrepancies in angular momentum values. Such discrepancies are well explained on the basis of input angular momentum involved in the reactions.

Evaporation residue cross sections of superheavy nuclei based on optimized nuclear data* *Supported by the National Natural Science Foundation of China (12175170, 11675066)

This study proposes an optimized method for estimating atomic nucleus masses by combining the finite-range droplet model (FRDM) with the support vector machine algorithm. The optimization process significantly improves the accuracy of the FRDM by reducing the root mean square error from 0.606 to 0.253 MeV. The optimized mass data obtained from this method are then used to calculate the evaporation residue cross-sections (ERCSs) for fusion-evaporation reactions, employing the di-nuclear system model. The experimental results for the 48Ca+238U reaction are relatively well reproduced using these optimized mass data. Additionally, the study investigates the impact of mass uncertainties on fusion and survival probabilities. By considering the mass uncertainties, the ERCSs for new elements 119 and 120 are predicted based on the obtained optimized mass data.