Pb Targets Research Articles

A muon beam monitor for the CHNet-MAXI experiment at the RIKEN-RAL laboratory

The CHNet-MAXI experiment (Muonic Atom X-ray and prompt gamma spectroscopy for Isotopic analysis for cultural heritage) is an INFN Cultural Heritage program funded by Scientific Commission V, aiming at selecting the best figures of merit in the isotopic analysis of lead by means of muonic atom emission. The experiment will be deployed at RIKEN-RAL facility ISIS-STFC (UK), providing a pulsed muon beams with momenta between 15 and 90 MeV/c. The CHNet-MAXI apparatus will be mainly based on a 9 HPGe detectors array and innovative scintillator detectors read-out by SiPMs for the detection of the characteristic X and gamma rays emitted by isotopically enriched targets of Pb 204, 206, 207 and 208, after negative muon irradiation at the RIKEN-RAL beamlines. A muon beam hodoscope will be used as a beam x/y profiler and as a beam intensity monitor. This detector has been designed to provide a few mm spacial resolution, and it is based on 3 mm thick scintillating fibers, each read-out by a single SiPM at one edge. The setup is meant to be portable thanks to desktop HV and innovative open-FPGA DAQ modules. All the phases of the design, assembly, and testing of the CHNet-MAXI hodoscope are illustrated. Finally, first operation tests of this new beam monitor are shown.

Selected Functions and Disorders of Mitochondrial Metabolism under Lead Exposure.

Mitochondria play a fundamental role in the energy metabolism of eukaryotic cells. Numerous studies indicate lead (Pb) as a widely occurring environmental factor capable of disrupting oxidative metabolism by modulating the mitochondrial processes. The multitude of known molecular targets of Pb and its strong affinity for biochemical pathways involving divalent metals suggest that it may pose a health threat at any given dose. Changes in the bioenergetics of cells exposed to Pb have been repeatedly demonstrated in research, primarily showing a reduced ability to synthesize ATP. In addition, lead interferes with mitochondrial-mediated processes essential for maintaining homeostasis, such as apoptosis, mitophagy, mitochondrial dynamics, and the inflammatory response. This article describes selected aspects of mitochondrial metabolism in relation to potential mechanisms of energy metabolism disorders induced by Pb.

Photon and neutron dose evaluation at the Beam Test Facility of the INFN - National Laboratory of Frascati

Dose evaluation and direct measurements are fundamental for radiation protection in non-conventional accelerator facilities, both before and after the primary and secondary shielding. In this paper, we will report about the experimental setup, data acquisition and analysis, together with FLUKA modeling, of the dose measurements test carried out in the Beam Test Facility (BTF) of the INFN - Frascati’s National Laboratories (LNF), where an intense mixed field is produced and measured with thermoluminescent dosimeters. BTF is an extraction and transport line of DAΦNE LINAC (Buonomo et al. 2021; Mazzitelli et al. 2003). It is optimized for electrons and positrons production in a wide range of intensity, energy (30 MeV–800 MeV), beam spot dimensions and divergence, using both primary and secondary beam of the DAΦNE LINAC. Through the years, the BTF has gained an important role in particle detectors test and development with electron/positron beam. A small fraction of the BTF’s shifts have been dedicated to radiation damage test using LINAC electron primary beam up to 5×1010 e-/s. As radiation protection group of the LNF, we evaluated the dose when electrons impinging on a Pb target from: (i) photon Bremsstrahlung production; (ii) photoneutron production. Three dedicated tests with 503 MeV electrons impinging on a ∼16 cm thick Pb target have been carried out in February, June 2022 and in January 2023, using TLD700 and TLD600, measuring doses at several charge intervals. The aim of this study focuses on evaluating dosimetric quantities produced by the mixed field, air kerma for the photon component, and ambient dose equivalent for the neutron one, using thermoluminescence dosimeters calibrated with low-energy standards: Cs-137 and Am-Be. The approach adopted involves the use of Monte Carlo simulations of the experiment, both to benchmark against experimental measurements and to validate the results obtained for energies higher than those of calibration. The results of this comparison show excellent agreement between measured and simulated quantities in the forward direction, allowing us to conclude and confirm the validity of the calibrations themselves.

Lead specifically declines tyrosine hydroxylase activity to induce the onset of Parkinson's disease through disrupting dopamine biosynthesis in fly models

Parkinson's disease (PD) is one of the fastest-growing neurodegenerative diseases and has been linked to the exposure to numerous environmental neurotoxins. Although lead (Pb) exposure has been related to the development of PD, the molecular target of Pb to cause the onset of PD is insufficiently investigated. Herein, we explored the effects of Pb exposure on behavior, pathophysiology, and gene expression of wild-type (WT) fly (Drosophila melanogaster) by comparison with its PD model. After exposure to Pb, the WT flies showed PD-like locomotor impairments and selective loss of dopaminergic (DAergic) neurons, displaying similar phenotypes to fly PD model (PINK1). Transcriptomic analysis showed the similarity in gene expression profiles between Pb treatment WT flies and PINK1 mutant flies. Moreover, Pb exposure resulted in endogenous dopamine deficits in WT flies. Analyses of gene expression and enzyme activity confirmed that Pb exposure reduced tyrosine hydroxylase (TH) activity and led to failure of dopamine synthesis. Furthermore, molecular dynamics simulation confirmed that Pb was adsorbed by TH and subsequently inhibited the enzymatic activity. Exogenous injection of L-dopa and melatonin could partially rescue the pathological phenotypes of Pb-exposed flies and PD fly model. Antagonist injection of microRNA-133, which negatively regulated the expression of TH gene, ultimately rescued in the manifestation of PD phenotypes in flies. Involvement of TH overexpression mutants of fly strongly promoted the resistance to Pb exposure and rescued both behavior and the number of DAergic neurons. Therefore, our study elucidates the Pb molecular target in dopamine pathway and mechanism underlying the risks of Pb exposure on the occurrence of PD at environmentally-relevant concentrations.

Fabrication of 208Pb and 193Ir targets on Al-backing using high/ultra-high vacuum deposition technique for low-energy nuclear reaction experiments

Aiming to study the interplay of different nuclear reactions at low incident energies, thin targets of enriched stable isotopes, 208Pb and 193Ir, have been fabricated at the target development laboratory of the Inter-University Accelerator Centre (IUAC), New Delhi. As a means of preparing a large number of thin isotopically pure targets, physical vapour deposition techniques, (a) resistive heating, for fabrication of 208Pb targets of mass thickness 160-340μg/cm2, and (b) electron-gun evaporation technique, for fabrication of 193Ir targets of mass thickness 17-60μg/cm2, have been employed. The fabricated targets were characterized using Rutherford Backscattering Spectrometry (RBS) and Field Emission Scanning Electron Microscopy (FE–SEM). The thickness of targets was estimated based on the evaporation rate and measured by RBS. The RBS was employed to analyse the samples for trace- and heavy impurities, provided the measurements and analysis suggest that the targets prepared in the present work do not contain any impurities. FE-SEM was employed to examine the surface morphology and microstructure in high resolution. This technique enables the detection of any morphological changes induced by the irradiation process, offering insights into the effects of irradiation on the target films. The targets have been successfully deployed to measure complete and incomplete fusion excitation functions, mass distribution of fission fragments, and forward ranges of target-like recoils in 12C + 208Pb, 193Ir reactions from sub- to above barrier energies. Preliminary data analysis suggests the achievement of high-quality 208Pb and 193Ir target foils.

TOPAS simulation of photoneutrons in radiotherapy: accuracy and speed with variance reduction

Objective. We provide optimal particle split numbers for speeding up TOPAS Monte Carlo simulations of linear accelerator (linac) treatment heads while maintaining accuracy. In addition, we provide a new TOPAS physics module for simulating photoneutron production and transport. Approach. TOPAS simulation of a Siemens Oncor linac was used to determine the optimal number of splits for directional bremsstrahlung splitting as a function of the field size for 6 MV and 18 MV x-ray beams. The linac simulation was validated against published data of lateral dose profiles and percentage depth-dose curves (PDD) for the largest square field (40 cm side). In separate simulations, neutron particle split and the custom TOPAS physics module was used to generate and transport photoneutrons, called ‘TsPhotoNeutron’. Verification of accuracy was performed by comparing simulations with published measurements of: (1) neutron yields as a function of beam energy for thick targets of Al, Cu, Ta, W, Pb and concrete; and (2) photoneutron energy spectrum at 40 cm laterally from the isocenter of the Oncor linac from an 18 MV beam with closed jaws and MLC. Main results. The optimal number of splits obtained for directional bremsstrahlung splitting enhanced the computational efficiency by two orders of magnitude. The efficiency decreased with increasing beam energy and field size. Calculated lateral profiles in the central region agreed within 1 mm/2% from measured data, PDD curves within 1 mm/1%. For the TOPAS physics module, at a split number of 146, the efficiency of computing photoneutron yields was enhanced by a factor of 27.6, whereas it improved the accuracy over existing Geant4 physics modules. Significance. This work provides simulation parameters and a new TOPAS physics module to improve the efficiency and accuracy of TOPAS simulations that involve photonuclear processes occurring in high-Z materials found in linac components, patient devices, and treatment rooms, as well as to explore new therapeutic modalities such as very-high energy electron therapy.

Incoherent J/ψ production at large |t| identifies the onset of saturation at the LHC

We predict that the onset of gluon saturation can be uniquely identified using incoherent J/ψ production in Pb–Pb collisions at currently accessible energies of the LHC. The diffractive incoherent photo-production of a J/ψ vector meson off a hadron provides information on the partonic structure of the hadron. Within the Good-Walker approach it specifically measures the variance over possible target configurations of the hadronic colour field. For this process then, gluon saturation sets in when the cross section reaches a maximum, as a function of the centre-of-mass energy of the photon-hadron system (W), and then decreases. We benchmark the energy-dependent hot-spot model against data from HERA and the LHC and demonstrate a good description of the available data. We show that the study of the energy dependence of the incoherent production of J/ψ allows us to pinpoint the onset of saturation effects by selecting the region of Mandelstam-t around 1 GeV2 where the contribution of hot spots is dominant. We predict the onset of saturation in a Pb target to occur for W around a few hundred GeV. This can be measured with current data in ultra-peripheral Pb–Pb collisions at the LHC.

Nonperturbative theory for the QED corrections to elastic electron-nucleus scattering

A potential for the vertex and self-energy correction is derived from the first-order Born theory. The inclusion of this potential in the Dirac equation, together with the Uehling potential for vacuum polarization, allows for a nonperturbative treatment of these quantum electrodynamical effects within the phase-shift analysis. Investigating the 12C and 208Pb targets, a considerable deviation of the respective cross section change from the Born results is found for the heavier target. It is shown that at low impact energies the dispersion effects play no role. Estimates for the correction to the beam-normal spin asymmetry and its accuracy at 5 MeV (for 208Pb and 197Au) are also provided.

Construction of density-dependent α-nucleon interaction to describe α-nucleus scattering

We provide a global density-dependent α-nucleon (DD-αN) interaction to construct the α-nucleus optical potential in a wide range of incident energies. The α-nucleus potential based on the folding model with the present DD-αN interaction reproduces the experimental data up to backward angles using the point-nucleon density obtained by the mean-field model. The present DD-αN interaction is based on the phenomenological optical potential to reproduce the p + 4He elastic scattering at the incident energies at 12.04–1000 MeV. Namely, the α-nucleon system is considered an elementary process. The density dependence (medium effect) of the DD-αN interaction is phenomenologically added to reproduce the α elastic scatterings by the 16O, 40Ca, 58Ni, 90Zr and 208Pb targets at E/A = 10–342.5 MeV. The total reaction cross sections are also compared with the experimental data.

Effect on incomplete fusion of breakup fragments of the weakly bound projectile 8B in reactions with targets 27Al, 28Si, 208Pb and 209Bi

Calculations of total, complete and incomplete fusion cross sections are presented as function of the incident energy of the weakly bound projectile 8B in reactions with light 27Al, 28Si and heavy 208Pb and 209Bi mass targets. In particular, the relative effect of the breakup fragments; proton and 7Be of 8B on incomplete fusion is determined. Also, the effect of an additional proton to the nuclear potential of the targets 28Si, 209Bi respect to 27Al and 208Pb is determined as a function of the incident energy. It is found that the proton absorption becomes more important than for 7Be for light targets for energies around and above the barrier, however, the inverse occurs for heavy targets. The calculations are performed with two different methods. The CDCC to determine the relative projectile-target radial wave functions which subsequently are used in the angular momentum-dependent model of fusion probabilities to calculate complete, incomplete and total fusion.

Experimental study of 6He Coulomb breakup as an indirect measurement of 4He(2n,γ)6He reaction rate for the astrophysical r-process

In this work, we report the measurement of elastic and Coulomb break-up channels in 6He+208Pb collisions at Elab = 19.3 MeV, close to the Coulomb barrier of this system ∼ 19 MeV. In the context of the astrophysical r-process, the reaction 4He(2n,γ)6He has been proposed to be a key reaction in the path of synthesizing seed nuclei for the r-process, as 12C, in an environment composed mainly of alpha particles and neutrons. Based on a theoretical approach for treating three body reactions by means of which its reaction rate can be inferred, our experimental approach aims to obtain an indirect measurement of the reaction rate of 4He(2n,γ)6He by measuring the Coulomb breakup of 6He under the intense electric field produced by a 208Pb target nucleus. The experiment was carried out at the TriSol facility operated in the Nuclear Science Laboratory of the University of Notre Dame, USA, which delivered a 6He beam together with other contaminants. Particular care must be taken for the alpha particles produced in the production reaction.

Elastic scattering of 13C and 14C isotopes on a 208Pb target at energies of approximately five times the Coulomb barriers* *Supported by the National Natural Science Foundation of China (12122511, 12105330), the Youth Innovation Promotion Association CAS (2020411), and funding from the State Key Laboratory of Nuclear Physics and Technology, Peking University (NPT2023KFY04). V. G. would like to thank CNPq

The elastic scattering angular distributions of C at 340 MeV and C at 294 MeV and 342 MeV on a Pb target, which correspond to approximately five times the Coulomb barriers, were measured at the Radioactive Ion Beam Line in Lanzhou. The data were analyzed within the optical model and continuum-discretized coupled-channels (CDCC) framework, and the results of both calculations could effectively account for the experimental data. The differential cross sections of elastic scattering revealed no particular suppression at the Coulomb nuclear interference peak angles, suggesting that the breakup coupling effects on the elastic scattering angular distributions were negligibly small in this incident energy region. The contributions from the couplings with inelastic states to the elastic cross sections were of minor importance within the angular range covered by these experiments.

Global density-dependent α–nucleon interaction for α–nucleus elastic scattering

Abstract We provide a global density-dependent 4He–nucleon (DD-αN) interaction to construct the α–nucleus optical model potential (OMP) across a wide range of incident energies. The global parametrization for the DD-αN interaction is obtained based on the proton–4He OMP, which reproduces the elastic scattering cross-section data very well in the incident energies of 12.04–500 MeV per nucleon. Using the present DD-αN interaction, we derive the α–nucleus potential by a folding procedure with the point-nucleon density obtained by a microscopic mean-field model. The density dependence of the DD-αN interaction is fixed phenomenologically to reproduce the α–nucleus elastic scattering cross-section data obtained from 16O, 40Ca, 58Ni, 90Zr, and 208Pb targets at E/A = 10–342.5 MeV. We also show the total reaction cross sections, which are helpful in fixing one free parameter, the renormalization factor for the imaginary part of the α–nucleus potential. Lastly, we show some examples, which clearly demonstrate the validity and power of the present DD-αN approach.

Identification of lead-binding proteins as carriers and potential molecular targets associated with systolic blood pressure

Lead (Pb) exposure is well recognized as a significant environmental factor associated with the high incidence of cardiovascular diseases. However, the carriers and molecular targets of Pb in human blood remain to be understood, especially for a real Pb exposure scenario. In this study, a total of 350 blood samples were collected from the smelting workers and systematically analyzed using metallomics and metalloproteomics approaches. The results showed that the majority of Pb (∼99.4%) could be presented in the blood cells. Pb in the cytoplasm of blood cells accounted for approximately 83.1% of the total blood Pb, with nearly half of Pb being bound to proteins. Pb-binding proteins in the blood of workers were identified as hemoglobin, catalase, haptoglobin, δ-aminolevulinic acid dehydratase, and peroxiredoxin-2. Multiple linear regression analysis demonstrated that higher levels of Pb bound to proteins (Mix-bound Pb and Protein-bound Pb) were positively associated with higher systolic blood pressure (p < 0.05). However, the association between blood lead level, Pb levels in the blood cells and systolic blood pressure was not observed (p > 0.05). This study suggested that Pb bound to proteins could be a suitable biomarker for indicating the potential risk of occupational hypertension.

Neutrino-Induced Coherent π^{+} Production in C, CH, Fe, and Pb at ⟨E_{ν}⟩∼6 GeV.

MINERvA has measured the ν_{μ}-induced coherent π^{+} cross section simultaneously in hydrocarbon (CH), graphite (C), iron (Fe), and lead (Pb) targets using neutrinos from 2 to 20GeV. The measurements exceed the predictions of the Rein-Sehgal and Berger-Sehgal PCAC based models at multi-GeV ν_{μ} energies and at produced π^{+} energies and angles, E_{π}>1 GeV and θ_{π}<10°. Measurements of the cross-section ratios of Fe and Pb relative to CH reveal the effective A scaling to increase from an approximate A^{1/3} scaling at few GeV to an A^{2/3} scaling for E_{ν}>10 GeV.

Skin values and matter radii of 208Pb and 58,60,64Ni based on reaction cross section of 3,4He scattering

Background:The PREX group reported a new skin value, rskin208(PREX2)=0.283±0.071=0.212∼0.354fm. Using the chiral (Kyushu) g-matrix folding model with the proton and neutron densities determined with D1S+GHFB+AMP, we determined neutron skin thickness rskin208(exp)=0.278±0.035 fm from reaction cross sections σR(exp) of p+208Pb scattering, where D1S-GHFB+AMP denotes Gogny-D1S HFB with angular momentum projection (AMP). The method also yielded rskin208(exp)=0.416±0.146 from σR(exp) of 4He+208Pb scattering. In our previous work, we accumulated the 206 EoSs and determined a sloop parameter L=76∼165MeV from the 206 EoSs. The value of L yields rskin208=0.102∼0.354fm. As for 58Ni, a novel method for measuring nuclear reactions in inverse kinematics with stored ion beams was successfully used to extract matter radii rm of 58Ni at the GSI facility. Purpose:As the first aim, we first determine rskin208(exp) from σR(exp) of 3He scattering on 208Pb target and take the weighted mean and its error for rskin208(PREX2), three skin values of p+208Pb, 3,4He+208Pb scattering and rskin208=0.102∼0.354fm based on the 206 EoSs. As the second aim, we determine matter radii rm(exp) of 58,60,64Ni from σR(exp) of 3,4He scattering on 58,60,64Ni targets. Results:Our result is rskin208(exp)=0.512±0.268fm for 3He+208Pb scattering. Our results based on 4He+58,60,64Ni scattering are rm58(exp)=3.734±0.091 fm, rm60(exp)=3.815±0.094 fm, rm64(exp)=4.001±0.093 fm. Our results based on 3He+58,60,64Ni scattering are rm58(exp)=3.709±0.098 fm, rm60(exp)=3.753±0.112 fm, rm64(exp)=3.822±0.142 fm. Conclusion:Our conclusion is rskin208=0.285±0.030fm. It is determined from the 5 skin values mentioned above.

Suppression of Coulomb-nuclear interference in the near-barrier elastic scattering of 17Ne from 208Pb

The proton drip-line nucleus 17Ne is considered a good candidate for a Borromean two-proton halo with a 15O + p + p structure. Angular distributions of the elastic scattering and inclusive 15O production for a 136 MeV 17Ne beam incident on a 208Pb target were measured for the first time at the SPIRAL1 facility, GANIL. Use of the GLORIA detector array allowed high-resolution data over a wide angular range from 20∘ up to 95∘ in the laboratory frame to be obtained. The elastic scattering angular distribution shows similarities with those for both 6He and 20Ne at equivalent collision energies with respect to the corresponding Coulomb barriers, exhibiting the suppression of the Coulomb rainbow peak characteristic of strong coupling. Optical model and coupled channel fits suggest that this is due to a combination of coupling to low-lying quadrupole resonances and Coulomb dipole coupling to the low-lying continuum, although their relative importance depends on the relevant B(E2) values which remain to be firmly determined.

Theoretical Study on 10C Elastic Scattering Cross Sections Using Different Cluster Density Distributions and Different Potentials

Elastic scattering cross sections are a fundamental aspect of nuclear physics research, and studying the cross sections of various nuclei can provide important insights into the behavior of nuclei. In this study, the elastic scattering cross sections of 10C projectile by 27Al, 58Ni, and 208Pb target nuclei are analyzed. The aim of this study is to investigate the cluster structure of 10C and the sensitivity of the elastic scattering cross sections to different potentials. To achieve this objective, the double folding optical model and a simple cluster approach are used to analyze the cross sections. The real part of the optical potential is obtained by folding two different effective interactions, Michigan-3-Yukawa (M3Y) and JeukenneLejeune-Mahaux (JLM), with four different cluster density distributions of the 10C nucleus: 6Be + \alpha, 9B + p, 8Be + p + p, and \alpha + \alpha + p + p. The imaginary part is taken to be a Woods-Saxon phenomenological form. The sensitivity of the elastic scattering cross sections to different potentials is assessed by comparing the results obtained using different potentials. The cluster structure of 10C is validated by comparing the theoretical results with experimental data. The results show that the cross sections are sensitive to the choice of potential used and that the cluster structure of 10C is validated. The theoretical results show reasonable agreement with the experimental data.

Antiparasitic Activity of Plumbago auriculata Extracts and Its Naphthoquinone Plumbagin against Trypanosoma cruzi.

Chagas disease (CD) caused by the protozoan Trypanosoma cruzi affects more than six million people worldwide. Treatment is restricted to benznidazole (Bz) and nifurtimox (Nf) that display low activity in the later chronic stage besides triggering toxic events that result in treatment abandonment. Therefore, new therapeutic options are necessary. In this scenario, natural products emerge as promising alternatives to treat CD. In the family Plumbaginaceae, Plumbago sp. exhibits a broad spectrum of biological and pharmacological activities. Thus, our main objective was to evaluate, in vitro and in silico, the biological effect of crude extracts of root and of aerial parts of P. auriculata, as well as its naphthoquinone Plumbagin (Pb) against T. cruzi. The phenotypic assays revealed potent activity of the root extract against different forms (trypomastigote and intracellular forms) and strains (Y and Tulahuen), with a compound concentration that reduced 50% of the number of the parasite (EC50) values ranging from 1.9 to 3.9 µg/mL. In silico analysis showed that Pb is predicted to have good oral absorption and permeability in Caco2 cells, besides excellent probability of absorption by human intestinal cells, without toxic or mutagenic potential effects, not being predicted as a substrate or inhibitor of P-glycoprotein. Pb was as potent as Bz against intracellular forms and displayed a superior trypanosomicidal effect (about 10-fold) in bloodstream forms (EC50 = 0.8 µM) as compared to the reference drug (8.5 µM). The cellular targets of Pb on T. cruzi were evaluated using electron microscopy assays and the findings on bloodstream trypomastigotes showed several cellular insults related to the autophagic process. Regarding toxicity in mammalian cells, the root extracts and the naphthoquinone present a moderate toxic profile on fibroblasts and cardiac cell lines. Then, aiming to reduce host toxicity, the root extract and Pb were tested in combination with Bz, and the data showed additive profiles with the sum of the fractional inhibitory concentration indexes (ΣFICIs) being 1.45 and 0.87, respectively. Thus, our work reveals the promising antiparasitic activity of Plumbago auriculata crude extracts and its purified naphthoquinone Plumbagin against different forms and strains of Trypanosoma cruzi in vitro.

Challenges to the Good-Walker paradigm in coherent and incoherent photoproduction

High-energy vector meson photoproduction is an important tool for studying the partonic structure of matter at low Bjorken$-x$. In the Good-Walker (GW) paradigm, the cross-section $d\sigma/dt$ for coherent production of vector mesons or other final states, depends the average transverse distribution of gluons, while the incoherent cross-section depends on fluctuations in the nuclear structure, due to variations in nucleon positions, and/or gluonic hot spots. However, predictions of the the GW paradigm seemingly conflict with data from multiple experiments which observe coherent production of vector mesons accompanied by nuclear excitation, or in peripheral relativistic heavy-ion collisions. These data are consistent with a simpler, semi-classical approach. We will discuss this contradiction and explore how and why GW fails. We will also contrast the significant differences in incoherent photoproduction on $^{197}$Au and $^{208}$Pb targets in the GW approach with the much smaller expected differences in their low$-x$ gluon content.