Quasi Elastic Research Articles

Precise determination of quadrupole and hexadecapole deformation parameters of the sd-shell nucleus, 28Si

Quasi-elastic (QEL) scattering measurements have been performed using a 28Si projectile off a 90Zr target at energies around the Coulomb barrier. A Bayesian analysis within the framework of coupled channels (CC) calculations is performed in a large parameter space of quadrupole and hexadecapole deformations (β2 and β4) of 28Si. Our results unambiguously show that 28Si is an oblate shaped nucleus with β2=-0.38±0.01 which is in excellent agreement with results from electromagnetic probes. The sign and magnitude of quadrupole deformation along with a precise value of hexadecapole deformation (β4=+0.03±0.01) of 28Si have been determined for the first time using QEL scattering. A remarkable agreement is obtained between the experimental and calculated β4 values of 28Si based on Skyrme-Hartree-Fock method. The present results demonstrate the strong sensitivity of the quasi-elastic scattering to the sign and magnitude to the ground state deformation parameters, thus affirming its suitability to be used for rare exotic nuclei using low intensity RIBs.

Electron beams near surfaces: the concept of partial intensities for surface analysis and perspective on the low energy regime

Electron beam techniques are indispensable tools for the analysis of surfaces in fundamental as well as applied fields of science and technology. Significant improvements have been made in the past decades in the quantitative understanding of electron spectra, particularly with respect to the near-surface transport of signal electrons. The concept of partial intensities is a simple approach providing physical insight into transport of electrons in solids, a numerically convenient means for spectrum modelling and an essential ingredient for spectrum interpretation. The energy-dissipation process of energetic electrons in solids is discussed from the perspective of the partial intensities, offering a unified model for any type of electron beam technique, be it in the quasi-elastic (QE) or the continuous slowing down (CSD) regime. Examples are given for modelling and analysis of electron spectra such as X-ray photoelectron spectra (XPS), Elastic peak electron spectra (EPES) and electron energy-loss spectra (EELS). The physical model as well as the quantities for electron beam interaction with solids are reviewed, and methods for spectrum modelling and analysis are presented. The examples considered demonstrate the high level of accuracy nowadays attainable for characterisation of surfaces and nanostructures employing techniques using medium energy electrons (>100 eV). This is in contrast to the low energy regime, where a number of problems prevent a similar level of understanding. The topic of low energy electrons (LEEs) is rapidly gaining importance since in this energy range the involved electrons not only act as signal carriers, but also actively participate in electrochemical processes of importance in fields ranging from nanotechnology to life sciences. Issues of future importance in the field of LEEs are discussed and recent developments such as the 2-dimensional electron cascade in the scanning field electron microscope are highlighted.

Machine learning application for dark matter - background classification in JUNO experiment

Jiangmen underground neutrino observatory (JUNO) has a potential to indirectly detect dark matter (DM), observing neutrino events from annihilations of DM trapped by the gravitational force in the solar core. Weakly interacting massive particle (WIMP) DM candidate with mass > 4 GeV has significant solar capture rate. In this work, we simulate JUNO neutrino events from the most dominated WIMP annihilation channel, . Given the high-energy neutrinos from massive WIMPs, we extend the neutrino-nucleon interactions in the detector to include quasi-elastic (QE) and deep inelastic scatterings (DIS). The most challenging background events in the energy range above 100 MeV is the atmospheric neutrinos (atmo). The pulse shape discrimination (PSD) method is usually applied to distinguish between DM and atmo. In this work, we apply machine learning (ML) techniques to distinguish between the background (BG) atmo and DM neutrino events. We found that the random forest algorithm gives the best results. Using ML, the accuracy of DM-atmo events classification is 93.8% while similar f1-score could be achieved. On the other hand, only 78.1 % accuracy is obtained using conventional PSD with linear regression (LR). The upper limit for spin-dependent DM-proton cross-section with the applied ML is 5.84 × 10−40 cm2 for a 10 GeV WIMP DM which is an improvement over the sensitivity of the LR method of by a factor of ∼ 2.8x.

Quasi Elastic Neutron Scattering model library

This paper reports on the development of a collection of dynamical models of one-dimensional peak profile functions used to fit dynamic structure factors S (Q, ħω) of Quasi Elastic Neutron Scattering (QENS) data. The objective of this development is to create a maintainable and interoperable Python library with models reusable in other projects related to the analysis of data from Quasi Elastic Neutron Scattering experiments. The ambition is that the library also will serve as a platform where scientists can make their models available for others. We illustrate how the library can be used by newcomers to the field as well as by experts via different examples. These examples, provided as Jupyter notebooks, show how the QENS models can be integrated in the whole QENS data processing pipeline.

Extraction of the Coulomb sum rule, transverse enhancement, and longitudinal quenching from an analysis of all available e−C12 and e−O16 cross section data

We report on a phenomenological analysis of all available electron scattering data on $^{12}\mathrm{C}$ (about 6600 differential cross section measurements) and on $^{16}\mathrm{O}$ (about 250 measurements) within the framework of the quasielastic (QE) superscaling model (including Pauli blocking). All QE and inelastic cross section measurements are included down to the lowest momentum transfer $\mathbf{q}$ (including photoproduction data). We find that there is enhancement of the transverse QE response function (${R}_{T}^{QE}$) and quenching of the QE longitudinal response function (${R}_{L}^{QE}$) at low $\mathbf{q}$ (in addition to Pauli blocking). We extract parametrizations of a multiplicative low $\mathbf{q}$ ``longitudinal quenching factor'' and an additive ``transverse enhancement'' contribution. Additionally, we find that the excitation of nuclear states contribute significantly (up to 30%) to the Coulomb sum rule $SL(\mathbf{q})$. We extract the most accurate determination of $SL(\mathbf{q})$ to date and find it to be in disagreement with random phase approximation (RPA) based calculations but in reasonable agreement with recent theoretical calculations, such as ``first principle Green's function Monte Carlo.''

Light-front holography model of the EMC effect

A new two-component model of the EMC effect based on Light-Front Holographic QCD (LFHQCD) is presented. The model suggests the EMC effect is the result of the nuclear potential breaking SU(6) symmetry. The model separates the $F_2^A$ nuclear structure function into two parts: a free contribution, involving the addition of proton and neutron structure functions weighted by the number of protons and neutrons respectively, and a nuclear/medium modified contribution that involves a universal function for all nuceli. Further, the model displays a connection with the correlation between the size of the EMC effect and the SRC pair density, $a_2$ - extracted from kinematic plateaus at around $x$ > 1 in inclusive quasi-elastic (QE) scattering.

Pion Production in νμ Charged Current Interactions on 40Ar in Deep Underground Neutrino Experiment

Understanding the pion generation and the consequences of final-state interactions (FSI) are critical for the data processing in all neutrino experiments. The energy utilized in modern neutrino researches of the resonance (RES) generation processes contributes significantly to the pion production. If a pion is absorbed in the nuclear matter after its production, the event may become unrecognizable from a quasielastic (QE) scattering process and act as a background. For oscillation experiments, estimating this background is critical, and it necessitates solid theoretical models for both pion generation at the primary vertex and after FSI. The number of pions created after FSI differs greatly from the number produced at the primary vertex due to FSI. Because neutrino detectors can only detect final-state particles, FSI obscures the proper information about particles created at the primary vertex. A detailed study of FSI is required to overcome this problem, which theoretical models incorporated in Monte Carlo (MC) neutrino event generators can provide. They should give theoretical results concerning the neutrino interactions for various researches, acting as a connection among both theoretical models and experimental data. In this paper, we provide simulated events for the pion creation in νμ charge current (CC) interactions on a 40Ar target in the Deep Underground Neutrino Experiment (DUNE) setup for two distinct MC generators: GENIE and NuWro. In comparison to GENIE (v-3.00.06), NuWro (v-19.02.2) is more opaque (less responsive) to the charge exchange and absorption processes; pions are more likely to be absorbed than produced during the intranuclear transport.

Fusion and back-angle quasielastic measurements in Si30+Gd156 near the Coulomb barrier

Background: Advancement in accelerator facilities has opened the door to dig deep to understand the interplay between nuclear reactions and structures. Although the influence of inelastic excitations on nuclear scattering and sub-barrier fusion is somewhat established, a clear understanding of nucleon transfer with a positive-$Q$ value is yet to achieve.Purpose: The objective of this paper is to examine the role of the $2n$-transfer channel with a positive $Q$ value on sub-barrier fusion and back-angle quasielastic (QE) scattering in the $^{30}\mathrm{Si}+^{156}\mathrm{Gd}$ reaction. Furthermore, extraction of barrier distributions (BDs) from fusion and QE scattering to infer their shapes is also a prime goal.Method: The excitation functions (EFs) of fusion and back-angle QE scattering have been measured over a wide range of incident beam energy around the Coulomb barrier using a recoil mass spectrometer. Furthermore, BDs have been extracted using the measured fusion and back-scattered QE data. The underlying findings have been analyzed within the framework of coupled-channel (CC) formalism using ccfull and ecc programs.Results: Fusion enhancement has been observed compared to those predicted from the one-dimensional barrier penetration model at sub-barrier energies. Fusion enhancement and QE EFs are explained by CC predictions considering the collective excitations among the colliding nuclei. The inclusion of $2n$ transfer and collective excitations in ccfull improves the fit to the experimental fusion data in a short span of energy window around the Coulomb barrier, whereas no significant effect has been observed at the sub-barrier region. However, no such effect of $2n$-pickup transfer has been observed from ecc model calculations. Thus, no firm conclusion can be made on the role of $2n$-pickup transfer with a positive $Q$ value in present measurements.Conclusion: Fusion EFs have been successfully explained by the CC calculations using ccfull and ecc model codes. No significant effect of the $2n$-pickup channel with a positive $Q$ value was observed on sub-barrier fusion enhancement. However, QE EFs are reproduced by considering the collective excitations and $2n$-transfer channel couplings. Fusion and QE BDs are similar in shape within the experimental uncertainty. One-dimensional barrier parameters extracted from the measured data agree with the different theoretical models. Also, the present system obeys the systematic based on deformation values after transfer at the exit.

Search for a bound di-neutron by comparing 3He(e,e'p)d and 3H(e,e'p)X measurements

We report on a search for a bound di-neutron by comparing electron-induced proton-knockout (e,e′p) measurements from Helium-3 (3He) and Tritium (3H). The measurements were performed at Jefferson Lab Hall A with a 4.326 GeV electron beam, and kinematics of large momentum transfer (〈Q2〉≈1.9 (GeV/c)2) and xB>1, to minimize contributions from non quasi-elastic (QE) reaction mechanisms. Analyzing the measured 3He missing mass (Mmiss) and missing energy (Emiss) distributions, we can distinguish the two-body break-up reaction, in which the residual proton-neutron system remains bound as a deuteron. In the 3H mirror case, under the exact same kinematic conditions, we do not identify a signature for a bound di-neutron with similar binding energy to that of the deuteron. We calculate exclusion limits as a function of the di-neutron binding energy and find that, for binding equivalent to the deuteron, the two-body break-up cross section on 3H is less than 0.9% of that on 3He in the measured kinematics at the 95% confidence level. This limit implies that the di-neutron content of the tritium spectral function is less than 1.5%. With a dedicated measurement using similar high resolution spectrometers, but lower beam energy and vacuum coupling, significantly better energy missing energy resolution could be achieved, extending the sensitivity of the method to search for a di-neutron with far smaller binding energy.

Effects of nucleon-nucleon short-range correlations on inclusive electron scattering

The nucleon-nucleon short-range correlation (NN-SRC) is one of the key issues of nuclear physics, which typically manifest themselves in high-momentum components of the nuclear momentum distributions. In this paper, the nuclear spectral functions based on the axially deformed relativistic mean-field model are developed to involve the NN-SRC. With the spectral functions, the inclusive electron scattering $(e,{e}^{\ensuremath{'}})$ cross sections are calculated within the plane-wave impulse approximation (PWIA) framework, including the quasielastic (QE) part and $\mathrm{\ensuremath{\Delta}}$ production part. Especially in the $\mathrm{\ensuremath{\Delta}}$ production region, we reconsider the electromagnetic structures of the nucleon resonance $\mathrm{\ensuremath{\Delta}}$(1232) and the scattering mechanisms, and thereby the theoretical calculations are improved effectively and the cross sections are well consistent with the experimental data. The theoretical $(e,{e}^{\ensuremath{'}})$ cross sections are further divided into NN-SRC and mean-field contributions. It is found that, at the kinematics $0.5\phantom{\rule{0.16em}{0ex}}{\mathrm{GeV}}^{2}<{Q}^{2}<1\phantom{\rule{0.16em}{0ex}}{\mathrm{GeV}}^{2}$, the QE peak and $\mathrm{\ensuremath{\Delta}}$ production peak not only reflect the mean-field structure but also are sensitive to the NN-SRC information. Finally, we provide another method to extract the strengths of NN-SRC from experimental cross sections for selected nuclei at the suitable kinematics.

Hadronization and Color Transparency

In this paper, the earlier studies by us on the production of hadrons in a nuclear environment are reviewed. A string-breaking model for the initial production of hadrons and a quantum-kinetic Giessen-Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model are used to describe the final state interactions of the newly formed (pre)hadrons. The latter are determined both by the formation times and by the time-development of the hadron–hadron cross section. First, it is shown that only a linear time dependence is able to describe the available hadronizatin data. Then, the results are compared with detailed data from HERMES and Jefferson Laboratory (JLAB) experiments; a rather good agreement is reached for all reactions, studied without any tuning of parameters. Predictions of spectra for pions and kaons for JLAB experiments at 12 GeV are also repeated. Finally, the absence of color transparency (CT) effects in the recent experiment on proton transparencies in quasi-elastic (QE) scattering events on nuclei is discussed. We propose to look instead for CT effects on protons in semi-inclusive deep inelastic scattering (SIDIS) events.

Simulation of the column bending test using an anisotropic viscoelastic shell model

Finite element simulation of the column bending test (CBT) is carried out using shell elements with anisotropic viscoelastic section properties. The CBT is an experimental method for evaluating the bending behavior of thin-ply high strain composites (TP-HSC), to support development of deployable composite booms for space structures. A linear viscoelastic shell formulation is derived and implemented using two solution techniques: quasi-elastic (QE) and direct integration (DI). The model inputs, namely Prony series of the ABD matrix, are obtained using Mechanics of Structure Genome. The model is implemented in Abaqus as a UGENS user-subroutine. Recent CBT experiments are briefly reviewed, and a shell element model is developed including the geometrically nonlinear features of the test. Comparisons of the test and analysis results show that the model is capable of predicting most of the measured trends. Nonuniform deformation is captured and emphasized in data reduction considerations. Although relaxation can be captured with QE implementation of the viscoelastic model, to capture the residual curvature DI implementation is necessary. Residual curvature measured in the tests, but not predicted by the present model, suggests that viscoplasticity should be considered. A demonstrative study also shows the potential of material model calibration using the virtual CBT developed in this work.

Quasi Elastic Neutron Scattering Study on Water Dynamics in Nafion Membrane

Quasi Elastic Neutron Scattering Study on Water Dynamics in Nafion Membrane

Inclusive electron scattering and the genie neutrino event generator

The extraction of neutrino mixing parameters from accelerator-based neutrino oscillation experiments relies on proper modeling of neutrino-nucleus scattering processes using neutrino-interaction event generators. Experimental tests of these generators are difficult due to the broad range of neutrino energies produced in accelerator-based beams and the low statistics of current experiments. Here we overcome these difficulties by exploiting the similarity of neutrino and electron interactions with nuclei to test neutrino event generators using high-precision inclusive electron scattering data. To this end, we revised the electron-scattering mode of the GENIE event generator ($e$-GENIE) to include electron-nucleus bremsstrahlung radiation effects and to use, when relevant, the exact same physics models and model parameters, as the standard neutrino-scattering version. We also implemented new models for quasielastic (QE) scattering and meson exchange currents (MEC) based on the theory-inspired SuSAv2 approach. Comparing the new $e$-GENIE predictions with inclusive electron scattering data, we find an overall adequate description of the data in the QE- and MEC-dominated lower energy transfer regime, especially when using the SuSAv2 models. Higher energy transfer-interactions, which are dominated by resonance production, are still not well modeled by $e$-GENIE.

Optimized dispatching of city-scale integrated energy system considering the flexibilities of city gas gate station and line packing

Integrated Energy System (IES) has been proved to be able to effectively improve energy utilization and economic benefits. In the day-ahead dispatch of city-scale IES, electricity-gas interconnection is widely used to realize energy complementarity among regions, where the pressure regulation and electricity-heat-gas coupling in the gas gate station powered by Combined Heating and Power (CHP) device are usually excluded. Therefore, with the gas gate station centered, CHP fired energy hub linearization model, the optimized dispatching model of city-scale IES considering the flexibilities of city gas gate station and line packing is established in this paper where an Integrated Electricity and Gas System (IEGS) is running among regional Combined Cooling, Heating and Power (CCHP) systems, applying power and natural gas coupled energy flow algorithm. Results of case studies verify the potential of pipeline storage compared with gas storage tanks up to an 8.391% reduction on overall operation cost, a 14.366% improvement on renewable energy utilization and charging/discharging cycles reaching only 0.197 times of those of tanks, especially in areas with rich renewable energy. Besides, regulated by CHP fired energy hub which is worth constructing for its economic benefits and alleviation of peak power supply pressure, the average pipeline pressure proportional to stored gas volume increases by 5.885%, enhancing the flexibility of line packing. Moreover, this paper demonstrates that heating economy of gas boilers and electric boilers in comparison to gas turbines rises in turn with the increase of Gas-Electricity Price Ratio (GEPR). Lastly, Quasi Elastic Coefficient (QEC) is defined to describe multi-energy consumption sensitivity to Time-Of-Use (TOU) energy tariff, which is helpful in energy pricing and equipment scheduling.

Quasielastic electromagnetic scattering cross sections and world data comparisons in the GENIE Monte Carlo event generator

The usage of Monte Carlo neutrino event generators (MC$\nu$EGs) is a norm within the high-energy $\nu$ scattering community. The relevance of quasielastic (QE) energy regimes to $\nu$ oscillation experiments implies that accurate calculations of $\nu A$ cross sections in this regime will be a key contributor to reducing the systematic uncertainties affecting the extraction of oscillation parameters. In spite of this, many MC$\nu$EGs utilize highly phenomenological, parameterized models of QE scattering cross sections. Moreover, a culture of validation of MC$\nu$EGs against prolific electron ($e$) scattering data has been historically lacking. In this work, we implement new $e A$ cross sections obtained from nuclear ab initio approaches in GENIE, the primary MC$\nu$EG utilized by the FNAL community. In particular, we utilize results from Quantum MC methods which solve the many-body nuclear problem in the Short-Time Approximation (STA), allowing consistent retention of two-nucleon dynamics which are crucial to explain available nuclear electromagnetic (electroweak) data over a wide range of energy and momentum transfers. This new implementation in GENIE is fully tested against the world QE electromagnetic data, finding agreement with available data below $\sim2\,$GeV of beam energy with the aid of a scaling function formalism. The STA is currently limited to study $A\leq12$ nuclei, however, its semi-inclusive multibody identity components are exportable to other many-body computational techniques such as Auxiliary Field Diffusion MC which can reach $A\leq40$ systems while continuing to realize the factorization contained within the STA's multinucleon dynamics. Together, these developments promise to make future experiments such as DUNE more accurate in their assessment of MC$\nu$EG systematics, $\nu$ properties, and potentially empower the discovery of physics beyond the Standard Model.

Application of new multicomponent nanosystems for overcoming doxorubicin resistance in breast cancer therapy

The multi-component nanosystems based on the branched copolymer dextran-graft-polyacrylamide in an anionic form (D-g-PAAan) with gold nanoparticles (AuNPs), photosensitizer Chlorine e6 (Ce6), and chemotherapeutic agent Doxorubicin (Dox) were developed for use in complex breast cancer therapy. The synthesized nanosystems were characterized by Quasi Elastic Light Scattering and Transmission Electron Microscopy and tested against the malignant cells MCF-7/Dox resistant to Dox. It is found that the addition of Dox as the fourth component to the three-component nanosystem D-g-PAAan/AuNPs/Ce6 leads to aggregation and, as a result, to decrease in efficiency of tumor treatment. The way to reduce unwanted aggregation in the four-component nanosystem D-g-PAAan/AuNPs/Ce6/Dox is proposed. The new nanosystems are shown to be effective in overcoming Dox resistance and killing cancer cells.

Bloch-Grüneisen temperature and universal scaling of normalized resistivity in doped graphene revisited

In this work, we resolved some controversial issues on the Bloch-Gr\"{u}neisen (BG) temperature in doped graphene via analytical and numerical calculations based on full inelastic electron-acoustic-phonon (EAP) scattering rate and various approximation schemes. Analytic results for BG temperature obtained by semi-inelastic (SI) approximation (which gives scattering rates in excellent agreement with the full inelastic scattering rates) are compared with those obtained by quasi-elastic (QE) approximation and the commonly adopted value of $\Theta^{LA}_{F} = 2\hbar v_{LA} k_F/k_B$. It is found that the commonly adopted BG temperature in graphene ($\Theta^{LA}_{F}$) is about 5 times larger than the value obtained by the QE approximation and about 2.5 times larger than that by the SI approximation, when using the crossing-point temperature where low-temperature and high-temperature limits of the resistivity meet. The corrected analytic relation based on SI approximation agrees extremely well with the transition temperatures determined by fitting the the low- and high-$T$ behavior of available experimental data of graphene's resistivity. We also introduce a way to determine the BG temperature including the full inelastic EAP scattering rate and the deviation of electron energy from the chemical potential ($\mu$) numerically by finding the maximum of $\partial \rho(\mu,T)/\partial T$. Using the analytic expression of $\Theta_{BG,1}$ we can prove that the normalized resistivity defined as $R_{1}=\rho(\mu,T)/\rho(\mu,\Theta_{BG,1})$ plotted as a function of $(T/\Theta_{BG,1})$ is independent of the carrier density. Applying our results to previous experimental data extracted shows a universal scaling behavior, which is different from previous studies.

Proton Dynamics in Palladium-Silver: An Inelastic Neutron Scattering Investigation.

Proton dynamics in Pd77Ag23 membranes is investigated by means of various neutron spectroscopic techniques, namely Quasi Elastic Neutron Scattering, Incoherent Inelastic Neutron Scattering, Neutron Transmission, and Deep Inelastic Neutron Scattering. Measurements carried out at the ISIS spallation neutron source using OSIRIS, MARI and VESUVIO spectrometers were performed at pressures of 1, 2, and 4 bar, and temperatures in the 330–673 K range. The energy interval spanned by the different instruments provides information on the proton dynamics in a time scale ranging from about 102 to 10−4 ps. The main finding is that the macroscopic diffusion process is determined by microscopic jump diffusion. In addition, the vibrational density of states of the H atoms in the metal lattice has been determined for a number of H concentrations and temperatures. These measurements follow a series of neutron diffraction experiments performed on the same sample and thus provide a complementary information for a thorough description of structural and dynamical properties of H-loaded Pd-Ag membranes.

Inclusive electron scattering off C12, Ca40 , and Ar40 : Effects of the meson exchange currents

The scattering of electrons on carbon, calcium, and argon targets are analyzed using an approach that incorporates the contributions to the electromagnetic response functions from the quasielastic (QE), inelastic processes, and two-particle and two-hole meson exchange current ($2p-2h$ MEC). This approach describes well the whole energy spectrum of data at very different kinematics. It is shown that the accuracy of the $(e,e')$ cross section calculations in the region between the QE and delta-resonance peaks, where the $2p-2h$ MEC contribution reaches its maximum value, depends on the momentum transfer $|\q|$ and at $|\q|>500$ MeV the calculated and measured cross sections are in agreement within the experimental uncertainties.