Derived Cross Sections Research Articles

Measurement of the radius dependence of charged-particle jet suppression in Pb–Pb collisions at [formula omitted

The ALICE Collaboration reports a differential measurement of inclusive jet suppression using pp and Pb–Pb collision data at a center-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV. Charged-particle jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, 0.5, and 0.6 in pp collisions and R=0.2, 0.4, 0.6 in central (0–10%), semi-central (30–50%), and peripheral (60–80%) Pb–Pb collisions. A novel approach based on machine learning is employed to mitigate the influence of jet background. This enables measurements of inclusive jet suppression in new regions of phase space, including down to the lowest jet pT≥40 GeV/c at R=0.6 in central Pb–Pb collisions. This is an important step for discriminating different models of jet quenching in the quark–gluon plasma. The transverse momentum spectra, nuclear modification factors, derived cross section, and nuclear modification factor ratios for different jet resolution parameters of charged-particle jets are presented and compared to model predictions. A mild dependence of the nuclear modification factor ratios on collision centrality and resolution parameter is observed. The results are compared to a variety of jet-quenching models with varying levels of agreement.

Activation cross sections of deuteron-induced reactions on natural rhenium up to 23 MeV

Activation cross sections of deuteron-induced reactions on natural rhenium were measured using the stacked-foil activation technique and γ-ray spectrometry. Production cross sections of 185,183m,183gOs and 188g,186g,184m,184g,183gRe were determined up to 23 MeV. The derived cross sections were compared with experimental literature data and the TENDL-2019 and TENDL-2021 values.

Comparison of the SCALE, SERPENT and MCNP Criticality Safety Calculation of the NPP Krško Spent Fuel Pool

Criticality safety reanalyzes of the NPP Krško spent fuel pool has been performed. Limiting criticality cases at optimal moderation conditions are calculated using different SCALE code versions (SCALE-4.4a, SCALE-5.1 and SCALE-6.1) with 44-group ENDF/B-V and 238-group ENDF/B-VII.0 derived cross section libraries. Relative small discrepancies are observed. Additional verification is provided with SERPENT and MCNP5 codes, which are capable to take into account neutron continuous energy cross section library based on ENDF/B-VII.0 files. Comparison has shown that the results of the pool design calculations are conservative, precluding racks criticality even at optimum moderation conditions.

New de-excitation rates of the open shell dicarbon monoxide C2O(X3Σ−) in collision with He(1S)

Abstract In order to derive accurate physical conditions of the interstellar clouds (like TMC-1) from the rotational transitions of C2O, collisional rates are needed. Based on a new two-dimensional potential energy surface (2D-PES), we report a new rate coefficients calculation of C2O(X3Σ−) induced by collision with He. This PES was obtained from the explicitly correlated restricted open-shell coupled cluster with single, double and perturbative triple excitation (rccsd(t)-f12) ab initio approach associated with aug-cc-pVTZ basis sets. The C2O–He PES presents one minimum below its dissociation limit with a well depth of 42.376 cm−1. The close-coupling quantum time independent formalism was used to derive cross sections for E ≤ 370 cm−1 and N ≤ 10. De-excitation rate coefficients are obtained for thermal temperature below 80 K.

Single and double K -shell vacancy production in slow Xe54+,53+ -Xe collisions

We present an experimental and theoretical study of symmetric $\textrm{Xe}^{54+}+\textrm{Xe}$ collisions at 50, 30, and 15 MeV/u, corresponding to strong perturbations with $v_K/v_\text{p}$ = 1.20, 1.55, and 2.20, respectively ($v_K$: classical $K$-shell orbital velocity, $v_\text{p}$: projectile velocity), as well as $\textrm{Xe}^{53+}+\textrm{Xe}$ collisions at 15 MeV/u. For each of these systems, x-ray spectra were measured under a forward angle of $35^\circ$ with respect to the projectile beam. Target satellite and hypersatellite radiation, $K\alpha_{2,1}^\mathrm{s}$ and $K\alpha_{2,1}^\mathrm{hs}$, respectively, were analyzed and used to derive cross section ratios for double-to-single target $K$-shell vacancy production. We compare our experimental results to relativistic time-dependent two-center calculations.

Multiple photodetachment of silicon anions via K -shell excitation and ionization

Experimental cross sections for $m$-fold photodetachment ($m=3-6$) of silicon anions via $K$-shell excitation and ionization were measured in the photon-energy range of 1830-1900 eV using the photon-ion merged-beams technique at a synchrotron light source. All cross sections exhibit a threshold behavior that is masked by pre-threshold resonances associated with the excitation of a $1s$ electron to higher, either partly occupied or unoccupied atomic subshells. Results from multi-configuration Dirac-Fock (MCDF) calculations agree with the experimentally derived cross sections for photo-absorption if small energy shifts are applied to the calculated resonance positions and detachment thresholds. Moreover, a systematic approach is applied for modeling the deexcitation cascades that set in after the initial creation of a $K$-shell hole. The resulting product charge-state distributions compare well with the measured ones for direct $K$-shell detachment but less well for resonant $K$-shell excitation. The present results are potentially useful for identifying silicon anions in cold plasmas such as interstellar gas clouds.

The $^{135}$Cs(n,$\gamma$) cross section at 30 and 500 keV

The neutron capture cross section of the unstable isotope $^{135}$Cs was measured relative to that of gold by means of the activation method. The sample was produced by ion implantation in a high resolution mass separator and irradiated with quasi-monoenergetic neutrons at 30 keV and 500 keV, using the $^{7}$Li(p,n)$^{7}$Be reaction. After the irradiations at the above energies, one more irradiation with thermal neutrons was used for defining the sample mass and for measuring the half-life of $^{136}$Cs. The neutron capture cross section was determined as 164 $\pm$ 10 mbarn and 34.8 $\pm$ 3.0 mbarn at 30 keV and 500 keV, respectively, and were used to normalize the theoretically derived cross section shape.

Windowed multipole representation of R -matrix cross sections

Nuclear cross sections are basic inputs to any nuclear computation. Campaigns of experiments are fitted with the parametric R-matrix model of quantum nuclear interactions, and the resulting cross sections are documented - both point-wise and as resonance parameters (with uncertainties) - in standard evaluated nuclear data libraries (ENDF, JEFF, BROND, JENDL, CENDL, TENDL): these constitute our common knowledge of fundamental nuclear physics. In the past decade, a collaborative effort has been deployed to establish a new nuclear cross section library format - the Windowed Multipole Library - with the goal of considerably reducing the cost of cross section calculations in nuclear transport simulations. This article lays the theoretical foundations underpinning these efforts. From general R-matrix scattering theory, we derive the windowed multipole representation of nuclear cross sections. Though physically and mathematically equivalent, the windowed multipole representation is particularly well suited for subsequent temperature treatment of angle-integrated cross sections: we show that accurate Doppler broadening can be performed analytically up to the first reaction threshold; and we derive cross sections temperature derivatives to any order. Furthermore, we here establish a way of converting the R-matrix resonance parameters uncertainty (covariance matrices) into windowed multipole parameters uncertainty. We show that generating stochastic nuclear cross sections by sampling from the resulting windowed multipole covariance matrix can reproduce the cross section uncertainty in the original nuclear data file. Through this foundational article, we hope to make the Windowed Multipole Representation accessible, reproducible, and usable for the nuclear physics community, as well as provide the theoretical basis for future research on expanding its capabilities.

Activation cross section measurement of alpha-particle induced reactions on natural neodymium

Excitation functions of alpha-particle induced reactions on natNd up to 50 MeV were measured at the RIKEN AVF cyclotron. To derive cross sections activation method, stacked target technique and gamma-ray spectrometry were adopted. Formations of 153,145Sm, 151,150,149,148m,148g,144,143Pm, and 149,147Nd were investigated. The results were compared with the previous experimental data and the TENDL-2019 data. Discrepancies among most of them were found.

Analysis of Associative Ionization Rates for Hypersonic Flows

Three of the key associative ionization reactions that lead to plasma formation around hypersonic vehicles are studied in detail. For production of , , and , cross sections derived from experimental measurements for the interactions of atoms in low-lying electronic states are compared to cross sections derived from the overall rates widely used to model these processes. The experimentally derived cross sections are then used to develop rate coefficients for each of the atomic interactions, including those in electronically excited states. Monte Carlo simulation is employed to determine the postreaction partitioning of energy across the products. The key finding of this study is that associative ionization for all three systems proceeds primarily through interactions involving at least one of the atoms lying in the first or second electronically excited state. Nonequilibrium between the translational and electronic modes of the atoms will therefore lead to a variation in the associative ionization rates. This conclusion indicates a need for a more comprehensive approach to modeling plasma generation in hypersonic flows that resolves the lowest lying electronic states of the atoms that participate in associative ionization.

Activation cross sections of deuteron-induced reactions on praseodymium up to 24 MeV

We measured activation cross sections of deuteron-induced reactions on 141Pr. The production cross sections of 141,140Nd, 142Pr, and 139Ce were determined up to 24 MeV using the stacked-foil activation technique and high-resolution γ-ray spectrometry. The derived cross sections were compared with experimental data studied earlier and theoretical model calculations. Our results are consistent with part of the previous data.

Modeling cluster formation driven variations in critical electric field of He and Xe near critical point based on electron scattering cross sections

The dielectric breakdown strength of supercritical He and supercritical Xe shows a steep decline near the critical point due to density fluctuation caused by cluster formation. Conventional gas discharge theories are limited in explaining the drastic dielectric strength variation of He and Xe near the critical point. In this study, a dielectric strength modeling approach that is based on the derived cross section data of clusters is utilized to estimate the dielectric strength decline of He and Xe near the critical point. The electron scattering cross section data of He and Xe clusters are derived from those of gaseous He and Xe. Based on the derived electron scattering cross section data, critical electric fields of various He and Xe clusters are modeled as a function of pressure by solving the Boltzmann equation. The proposed modeling approach shows close agreement with the experimentally measured breakdown electrical fields reported in the literature.

Quantitative Interpretation of Electron Spectroscopy Signals. Extracting the Differential Inverse Inelastic Mean Free Path and Differential Surface Excitation Probability in Solids

A method for extracting the differential inelastic scattering cross sections of electrons xin(Δ) from the energy spectra of electron spectroscopy is developed. The derived cross sections are verified by interpreting experimental data on electron-energy-loss spectra, X-ray photoelectron spectroscopy, and Auger spectroscopy. The paper highlights existing methods for determining the cross sections xin(Δ) using electron-energy-loss spectra. Inconsistency in analytical solution of the inverse problem (i.e., deconvolution) is shown for calculating the inelastic scattering cross section of electrons xin(Δ). In this paper, the solution of the mathematically ill-posed problem of cross-section retrieval is based on a fitting procedure consisting in multiple direct-problem calculations, i.e., calculations of the electron spectra taking into account both elastic and inelastic multiple scattering events. To implement an efficient fitting algorithm, a high-performance procedure for solving the direct problem of determining the energy spectra of electron spectroscopy is developed. The method for calculating the spectra is based on solution of the boundary problem for the transport equation by using the invariant imbedding method. The procedure developed in this work allows the energy-loss cross sections in the surface layer and in the sample homogeneous bulk layer remote from the surface to be reconstructed. The cross sections xin(Δ) retrieved from experimental data on the electron-energy-loss spectra satisfactorily reproduce the Auger spectroscopy and X-ray photoelectron spectroscopy signals and vice versa: the cross sections xin(Δ) retrieved from the X-ray photoelectron spectroscopy data satisfactorily reproduce the electron-energy loss and Auger spectroscopy spectra. It is shown that for the description of the X-ray photoelectron spectroscopy spectra of Be, Mg, Al, Nb, and W, it is not necessary to use additional mechanisms of energy losses, so-called “intrinsic excitations”.

Applying Modern Surveying Techniques and Simulation Models for The Rehabilitation of Main Canals in Egypt: Case Study – El-Bagoriya Canal تطبیق تقنیات المسح الحدیثة ونماذج المحاکاة الهیدرولیکیة لإعادة تأهیل الترع الرئیسیة فی مصر دراسة حالة - قناة الباجوریة

El-Bagoriya canal is a main canal in the Middle Delta and it is the main water source for West Kafr El-Sheikh irrigation directorate. As originally a natural canal, El-Bagoriya canal has specific characteristics that affected its hydraulic performance, and which resulted in a problem in conveying required water supply to downstream irrigation directorates. With the installation of two new municipal stations on the canal, there was a plan to dredge the canal inside El-Monofiya irrigation directorate to increase its hydraulic capacity. A research project was conducted to help the irrigation directorate implementing the dredging in the best way. The research activities included surveying the cross sections using modern surveying techniques, using ArcMap program to develop contour maps from the surveyed points and derive cross sections from these counter maps. The activities also included using the simulation model to check the original situation, the suggested dredging scenario, and the actual dredging. The results showed that the suggested dredging could improve the flow inside the investigated reach from 53.5 m3/sec to 64.5 m3/sec while maintaining minimum water slope inside the reach. Actual dredging could improve the flow inside this reach to 57.5 m3/sec while maintaining the same water slopes.

Exploitation of surrogate reaction method for deriving proton induced fission cross sections of short lived actinides

In this article we have explored the possibility of measuring the proton induced fission cross sections using surrogate reaction method. To establish the validity of the surrogate method, we have derived the cross sections for 240Pu(p, f), 234Th(p, f), 236U(p, f) and 233Th(p, f) reactions using the derived cross section data of 240Am(n, f), 234Pa(n, f), 236Np(n, f) and 233Pa(n, f) reactions, which were measured by the surrogate ratio method. To extract the data, we have used the independence hypothesis of compound nucleus formation and derived a relation between proton and neutron induced fission cross sections of the consecutive isobars. The validity of the Weisskopf–Ewing approximation has been studied in detail. This study successfully confirms that the surrogate ratio method can be used to derive (p, f) cross sections of the short lived actinides. It is also concluded that a common surrogate reaction can be used for the determination of (n, f) and (p, f) cross sections for the consecutive isobars.

Determining cross sections from transport coefficients using deep neural networks

We present a neural network for the solution of the inverse swarm problem of deriving cross sections from swarm transport data. To account for the uncertainty inherent to this somewhat ill-posed inverse problem, we train the neural network using cross sections from the LXCat project, paired with associated transport coefficients found by the numerical solution of Boltzmann’s equation. The use of experimentally measured and theoretically calculated cross sections for training encourages the network to avoid unphysical solutions, such as those containing spurious energy-dependent oscillations. We successfully apply this machine learning approach to simulated swarm data for electron transport in helium, separately determining its elastic momentum transfer and ionisation cross sections to within an accuracy of 4% over the range of energies considered. Our attempt to extend our method to argon was less successful, although the reason for that observation is well-understood. Finally, we explore the feasibility of simultaneously determining cross sections of helium using this approach. We have some success here, determining elastic, total n = 2 excitation and ionisation cross sections to 10%, 20% and 25% accuracy, respectively. We are unsuccessful in properly unfolding the separate n = 2 singlet and triplet excitation cross sections of helium, but this is as expected given their similar threshold energies.

Neutron capture and total cross-section measurements of 155Gd and 157Gd at ANNRI in J-PARC

Neutron capture and total cross sections of 155Gd and 157Gd were measured with the neutron time-of-flight method in Accurate Neutron-Nucleus Reaction measurement Instrument at Material and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex using the NaI (Tl) spectrometer and Li-glass detectors. Preliminary cross sections were obtained in the neutron energy region from 4 meV to 100 meV. The derived cross sections agree with evaluated values in JENDL 4.0 and the experimental results by Mastromarco but were not consistent with those by Leinweber.

Probing entanglement in Compton interactions

This theoretical research aims to examine areas of the Compton cross section of entangled annihilation photons for the purpose of testing for possible break down of theory, which could have consequences for predicted optimal capabilities of Compton PET systems. We provide maps of the cross section for entangled annihilation photons for experimental verification. We introduce a strategy to derive cross sections in a relatively straight forward manner for the Compton scattering of a hypothetical separable, mixed and entangled states. To understand the effect that entanglement has on the cross section for annihilation photons, we derive the cross section so that it is expressed in terms of the cross section of a hypothetical separable state and of a hypothetical forbidden maximally entangled state. We find lobe-like structures in the cross section which are regions where entanglement has the greatest effect. We also find that mixed states do not reproduce the cross section for annihilation photons, contrary to a recent investigation which reported otherwise. We review the motivation and method of the most precise Compton scattering experiment for annihilation photons, in order to resolve conflicting reports regarding the extent to which the cross section itself has been experimentally verified.

Electron scattering from a deeply bound nucleon on the light-front

We calculate the cross section of the electron scattering from a bound nucleon within light-front approximation. The advantage of this approximation is the possibility of systematic account for the off-shell effects which become essential in high energy electro-nuclear processes aimed at probing the nuclear structure at small distances. We derive a new dynamical parameter which allows to control the extent of the "off-shellness" of electron - bound-nucleon electromagnetic current for different regions of momentum transfer and initial light-cone momenta of the bound nucleon. The derived cross section is compared with the results of other approaches in treating the off-shell effects in electron-nucleon scattering.

Assessing glacial modification of bedrock valleys using a novel approach

Analysis of valley cross sections is an established technique for evaluating the effects of glacial erosion. Here, we present a semiautomated approach for assessing glacial modification of bedrock valleys by quantifying morphological variability in valley cross sections extracted in bulk from digital elevation models (DEMs). This method can be tailored to derive cross sections of user-specified width and spacing and can generate cross-sectional data sets of multiple orders of magnitude. We demonstrate the technique by extracting ~27,000 cross sections from the Sierra Nevada, California, and computing measures of valley morphology including a form ratio, a quadratic curve fit, and a power law curve fit for each cross section. In addition, we introduce a novel metric, the V-index, which is calculated by comparing valley cross-sectional area to that of an ideal V-shaped cross section and is, thus, an expression of the deviation from an ideal V-shaped form. Statistical comparisons of the different measures suggest that the V-index is a robust alternative to traditional morphological measures because it can accommodate irregular valley cross sections and discriminate between glacial and nonglacial forms. We document the distribution of valley forms throughout the Sierra Nevada using the V-index to identify range-scale patterns in cross-sectional morphology and to investigate the role of lithology on glacial modification of bedrock valleys.