Inelastic Scattering Research Articles

Extraction of the valence transversity distributions from SIDIS data

The transversity distribution for $u$ and $d$ quarks is usually extracted from data on spin asymmetries in Semi Inclusive Deep Inelastic Scattering (SIDIS): however, due to its chiral odd nature, it has to be coupled to another chiral odd function, typically the Collins or the di-hadron fragmentation function. A recent suggestion of considering SIDIS data involving ratios of spin asymmetries and avoiding a knowledge of the Collins function, is briefly discussed. New measurements, involving ratios of cross sections, are suggested. They would allow a direct extraction of the transversity ratio, $h_1^{d_V}/h_1^{u_V}$. Numerical estimates are given.

Elastic and inelastic scattering of cosmic rays on sub-GeV dark matter

We revisit the signatures from collisions of cosmic-rays on sub-GeV dark matter (DM) in the Milky Way. In addition to the upscattered DM component that can be probed by existing DM and neutrino experiments widely discussed, we examine the associated signals in $\gamma$-rays and neutrinos that span a wide energy range due to the inelastic scatterings. Assuming a simple vector portal DM model for illustration, we compute both the upscattered DM flux by cosmic-ray protons, and the resulting emission of secondary $\gamma$-rays and high-energy neutrinos from proton excitation, hadronization, and the subsequent meson decay. We derive limits on coupling constants in the vector portal model using data from the $\gamma$-ray and high-energy neutrino telescopes including Fermi, H.E.S.S. and IceCube. These limits are compared to those obtained by considering the upscattered DM signals at the low-energy DM/neutrino detectors XENON1T/MiniBooNE and the IceCube. For this particular model, the limits are set predominantly by non-detection of the upscattered DM events in XENON1T, for most of the DM mass range due to the large scattering cross section at low energies. Nevertheless, our study demonstrates that the $\gamma$-ray and neutrino signals, traditionally considered as indirect probes for DM annihilation and decay, can also be directly used to constrain the DM--nucleon interaction in complementary to the direct search experiments.

Possible light neutral boson and particle mass quantization * *Supported by the National Natural Science Foundation of China (10175091, 11305007)

Qualities of nucleons, such as the fundamental parameter mass, might be modified in extreme conditions relative to those of isolated nucleons. We show the ratio of the EMC-effect tagged nucleon mass to that of the free one ( ); these values are derived from the nuclear structure function ratio between heavy nuclei and deuterium measured in the electron Deep Inelastic Scattering (DIS) reaction in 0.3 0.7. The increase in with is phenomenologically interpreted via the release of a color-singlet cluster formed by sea quarks and gluons in bound nucleons holding high momentum in the nucleus, from which the mass and fraction of non-nucleonic components in nuclei can be deduced. The mass of color-singlet clusters released per short range correlated (SRC) proton in the high momentum region ( 2 fm ) is extracted to be 16.890 0.016 MeV/c , which evidences the possibility of a light neutral boson and quantized mass of matter.

Investigations of Hydrocarbon Species on Solid Catalysts by Inelastic Neutron Scattering

The status of surface species on solid catalysts during heterogeneous catalysis is often mysterious. Investigations of these surface species are crucial to deconvolute the reaction network and design more efficient catalysts. Vibrational spectroscopy is a powerful technique to study the interactions between surface species and the catalysts and infrared (IR) and Raman spectroscopies have been widely applied to study reaction mechanisms in heterogeneous catalysis. However, IR/Raman spectra are difficult to model computationally and important vibrational modes may be IR-, Raman- (or both) inactive due to restrictions by optical selection rules. Inelastic neutron scattering (INS) is another form of vibrational spectroscopy and relies on the scattering of neutrons by the atomic nucleus. A consequence of this is that INS is not subject to any optical selection rules and all vibrations are measurable in principle. INS spectroscopy has been used to investigate surface species on catalysts in a wide range of heterogeneous catalytic reactions. In this mini-review, we focus on applications of INS in two important fields: petrochemical reactions and C1 chemistry. We introduce the basic principles of the INS technique, followed by a discussion of its application in investigating two key catalytic systems: (i) the behaviour of hydrocarbons on metal-oxide and zeolite catalysts and (ii) the formation of hydrocarbonaceous species on methane reforming and Fischer–Tropsch catalysts. The power of INS in studying these important catalytic systems is demonstrated.

Application of Nuclear Inelastic Scattering Spectroscopy to the Frequency Scale Calibration of Ab Initio Calculated Phonon Density of States of Quasi-One-Dimensional Ternary Iron Chalcogenide RbFeSe2

This study aims to examine the applicability of nuclear inelastic scattering (NIS) and conventional Mössbauer spectroscopy for calibration of the frequency scale of ab initio calculated phonon density of states (PDOS) of iron ternary chalcogenides. NIS measurements are carried out on the quasi-one-dimensional ternary chalcogenide RbFeSe2 to obtain the partial PDOS of the iron atoms in the compound. We compare the experimental PDOS with our previous results on vibrational properties of RbFeSe2 obtained with density functional theory (DFT) ab initio calculations, conventional Mössbauer, and infra-red spectroscopies. The experimental PDOS measured by NIS is collated with the ab initio calculated one. The frequency correction factor for the ab initio results is determined as 1.077, in good agreement with value of 1.08 obtained previously from the temperature dependence of the Lamb–Mössbauer factor of the iron atoms in RbFeSe2. We conclude that nuclear inelastic scattering and temperature dependence of the Lamb–Mössbauer factor in conventional Mössbauer spectroscopy can be equally applied for evaluation of the frequency correction factor for ab initio calculated phonon density of iron of ternary chalcogenides.

Detection module of the C-BORD Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS)

This article reports a detailed description of the integration tests of the first Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) carried out at the European Commission’s Joint Research Centre in Ispra (Italy). This technology allows the detection and identification of suspicious or illicit materials (such as narcotics, explosives, contraband goods, etc.) inside a cargo container using active neutron interrogation, with the so-called associated particle technique. The method is based on the measurement of the gamma photons emitted by the de-excitation of nuclei that undergo, mainly, inelastic scatterings with incident fast neutrons (En∼ 14 MeV). A set of scintillation detectors (NaI:Tl and LaBr3:Ce) is employed to perform gamma spectroscopy. The data acquisition system is based on fast signal digitizers and customized data acquisition software. A general technical description of the detection module and an outline of the data acquisition system (DAQ) are given. Also, we present the results of the integration tests, in particular, some examples of the performance of the system in the laboratory are shown, specifically, when using no target (background measurement) and when using mono-elemental and an explosive simulant target. Obtained results suggest that all technical requirements are achieved, and the next step will be the field trials.

Inelastic Scattering form Factors for Carbon and Oxygen Halo Isotopes

Inelastic Scattering form Factors for Carbon and Oxygen Halo Isotopes

Analysis of the EMCCD point-source response using x-rays

Electron Multiplying Charge Coupled Devices, EMCCD are used as x-ray detectors. The NSLS-II Soft Inelastic x-ray Scattering (SIX) beam line has two EMCCDs for x-ray detection in the spectrometer arm. The spectrometer with high resolving power disperses x-rays vertically. The x-ray vertical position on the sensor plane is related to its energy. This allows for very accurate x-ray energy measurements through x-ray coordinates. X-rays interact with silicon and create a number of electron–hole pairs proportional to the x-ray energy. Electrons drift and diffuse toward pixel gates and are collected there. The diffused electrons form a charge cloud distributed over several neighboring pixels. This charge sharing enables coordinate measurements with accuracy better than the pixel pitch. The charge distribution shape has to be taken into account to achieve ultimate accuracy in coordinate measurements. In this paper, we present a method of the charge distribution shape analysis and demonstrate its applications.The drift and diffusion of electrons from the point of generation to pixel gates results in the bell-shaped electron cloud usually approximated by Gaussian shape. The number of electrons collected under a pixel is proportional to the shape function integral. These electron packets get transferred to the sense node of the output amplifier. The transfer process could introduce distortions to the original charge distribution. For example, during transfers, electrons in the packet could be exposed to traps if they are present in the sensor. The trapping and later the release processes distort the apparent shape of the charge distribution. Therefore, deviations of the charge distribution shape from the originally symmetrical form can indicate the presence of trap centers in the sensor and can be used for sensor diagnostics.

Jet Production in Polarized Deep Inelastic Scattering at Next-to-Next-to-Leading Order.

We present the next-to-next-to-leading order (NNLO) calculation for single-inclusive jet production in polarized deep inelastic lepton-nucleon scattering e[over →]p[over →]→jet+X. We perform the computation based on the projection-to-Born method by combining our recent next-to-leading order result for di-jet production in polarized deep inelastic lepton-nucleon scattering along with the NNLO coefficients for the inclusive cross section. In this way, we achieve NNLO accuracy in a fully exclusive way for single-jet observables, the first time for a polarized cross section. We study the perturbative stability and phenomenological consequences of the QCD corrections for Electron-Ion Collider kinematics.

Elastic and Inelastic Electron-Nucleus Scattering Form Factors for Be9 Nucleus

The computations of the elastic and inelastic Coulomb form factors for the electron-nucleus scattering of Beryllium nucleus Be9 have performed with Core Polarization (CP) effects including the realistic Michigan sum of Three Range Yukawa (M3Y) Interaction, and the other residual interaction which is Modified Surface Delta Interaction (MSDI). In addition to mean square root charge density and charge radii for the ground state. The perturbation theory was adopted to compute the Core Polarization by using the Harmonic Oscillators (HO) potential to calculate single-particle radial wave functions.
 In the comparison between the theoretical calculations of Coulomb form factors by (MSDI) interaction, realistic (M3Y) interaction, and the experimental results that measured before, it noticed that the Coulomb form factors for the (M3Y) interaction gave a reasonable depiction of the measured data.

Observation of Double Excitations in the Resonant Inelastic X-ray Scattering of Nitric Oxide.

The nitrogen K-edge resonant inelastic X-ray scattering (RIXS) map of nitric oxide (NO) has been measured and simulated to provide a detailed analysis of the observed features. High-resolution experimental RIXS maps were collected using an in situ gas flow cell and a high-transmission soft X-ray spectrometer. Accurate descriptions of the ground, excited, and core-excited states are based upon restricted active space self-consistent-field calculations using second order multiconfigurational perturbation theory. The nitrogen K-edge RIXS map of NO shows a range of features that can be assigned to intermediate states arising from 1s → π* and 1s → Rydberg excitations; additional bands are attributed to doubly excited intermediate states comprising 1s → π* and π → π* excitations. These results provide a detailed picture of RIXS for an open-shell molecule and an extensive description of the core-excited electronic structure of NO, an important molecule in many chemical and biological processes.

Imaging Nanoscale Optical Fields with Inelastic Electron-light Scattering

Imaging Nanoscale Optical Fields with Inelastic Electron-light Scattering

Theory for High‐Angular‐Resolution Photoelectron Holograms Considering the Inelastic Mean Free Path and the Formation Mechanism of Quasi‐Kikuchi Band

In recent years, highly accurate measurements of photoelectron holograms have become possible through the development of electron energy analyzers with an energy range of 300–1000 eV. Effects of the inelastic mean free path (IMFP) and thermal vibration became apparent in the hologram pattern. For example, the quasi‐Kikuchi band is clearly observed, which cannot be explained by conventional multiple scattering theories. Herein, the theory of photoelectron holograms is summarized, considering the inelastic scattering (IES) and thermal vibration effects. Furthermore, the simulated hologram is compared with a diamond hologram measured at a kinetic energy of 563.4 eV. It is also shown that the formation mechanism of the quasi‐Kikuchi band differs from that of the normal Kikuchi band.

Multiple coupled charge layers in electron beam induced charging phenomenon

We report a discovery of the multiple coupled charge layer phenomenon in an insulating solid, SiO2, when irradiated by an electron beam with the aid of a Monte Carlo method. In tracing the transporting electrons, their encountered elastic, inelastic, and phonon scatterings, in conjunction with the influence of the electric field, are incorporated to model their transport more accurately. In handling charging, we consider the trapping of holes and energy-exhausted electrons on their drift paths, with the use of the electric-field-dependent drift velocity and trapping cross section. The emission of secondary electrons is modified by considering their trapping on the emission paths. Besides, the trapped charges may become detrapped under the electric field, which is also taken into account. Totally, six (three coupled) alternating charge layers are formed, with each layer having a thickness of about 0.1 μm, being parallel to the sample surface and existing merely along the beam incidence axis. The first layer is positive and is formed by secondary electron emission, while the sixth layer is negative and is formed by the extensive trapping of primary electrons. The middle four layers are formed by charge drift, in which electrons and holes move to opposite directions. However, the layer number remains unchanged with the increasing primary energy, since the charging involved in the simulation is negative, in which the primary electrons of different energies would be decelerated to a similar landing energy of 2–3 keV.

Inelastic Scattering of CN Radicals at the Gas–Liquid Interface Probed by Frequency-Modulated Absorption Spectroscopy

We describe the results of the first application of frequency-modulated (FM) absorption spectroscopy to molecular scattering dynamics at a gas–liquid interface. A pulsed direct-current (dc) electri...

Towards the nucleon hadronic tensor from lattice QCD

We present the first calculation of the hadronic tensor on the lattice for the nucleon. The hadronic tensor can be used to extract the structure functions in deep inelastic scatterings and also provide information for the neutrino-nucleon scattering which is crucial to the neutrino-nucleus scattering experiments at low energies. The most challenging part in the calculation is to solve an inverse problem. We have implemented and tested three algorithms using mock data, showing that the Bayesian Reconstruction method has the best resolution in extracting peak structures while the Backus-Gilbert and Maximum Entropy methods are somewhat more stable for the flat spectral function. Numerical results are presented for both the elastic case (clover fermions on domain wall configuration with $m_\pi\sim$ 370 MeV and $a\sim$ 0.06 fm) and a case (anisotropic clover lattice with $m_\pi\sim$ 380 MeV and $a_t\sim$ 0.035 fm) with large momentum transfer. For the former case, the reconstructed Minkowski hadronic tensor gives precisely the vector charge which proves the feasibility of the approach. While for the latter case, the nucleon resonances and possibly shallow inelastic scattering contributions around $\nu=1$ GeV are clearly observed but no information is obtained for higher excited states with $\nu>2$ GeV. A check of the effective masses of $\rho$ meson with different lattice setups indicates that, in order to reach higher energy transfers, using lattices with smaller lattice spacings is essential.

Positron Scattering from Atoms and Molecules

A review on the positron scattering from atoms and molecules is presented in this article. The focus on positron scattering studies is on the rise due to their presence in various fields and application of cross section data in such environments. Positron scattering is usually investigated using theoretical approaches that are similar to those for electron scattering, being its anti-particle. However, most experimental or theoretical studies are limited to the investigation of electron and positron scattering from inert gases, single electron systems and simple or symmetric molecules. Optical potential and polarized orbital approaches are the widely used methods for investigating positron scattering from atoms. Close coupling approach has also been used for scattering from atoms, but for lighter targets with low energy projectiles. The theoretical approaches have been quite successful in predicting cross sections and agree reasonably well with experimental measurements. The comparison is generally good for electrons for both elastic and inelastic scatterings cross sections, while spin polarization has been critical due to its sensitive perturbing interaction. Positron scattering cross sections show relatively less features than that of electron scattering. The features of positron impact elastic scattering have been consistent with experiment, while total cross section requires significant improvement. For scattering from molecules, utilization of both spherical complex optical potential and R-matrix methods have proved to be efficient in predicting cross sections in their respective energy ranges. The results obtained shows reasonable comparison with most of the existing data, wherever available. In the present article we illustrate these findings with a list of comprehensive references to data sources, albeit not exhaustive.

Resonant Inelastic X-Ray Scattering Reveals Hidden Local Transitions of the Aqueous OH Radical.

Resonant inelastic x-ray scattering (RIXS) provides remarkable opportunities to interrogate ultrafast dynamics in liquids. Here we use RIXS to study the fundamentally and practically important hydroxyl radical in liquid water, OH(aq). Impulsive ionization of pure liquid water produced a short-lived population of OH(aq), which was probed using femtosecond x-rays from an x-ray free-electron laser. We find that RIXS reveals localized electronic transitions that are masked in the ultraviolet absorption spectrum by strong charge-transfer transitions-thus providing a means to investigate the evolving electronic structure and reactivity of the hydroxyl radical in aqueous and heterogeneous environments. First-principles calculations provide interpretation of the main spectral features.

Three-terminal interface as a thermoelectric generator beyond the Seebeck effect

We investigate thermoelectric transport through interfaces with inelastic scatterings by developing a quantum theory, which has been extensively validated by existing theories. We find that under temperature bias, while a two-terminal conductor-insulator interface behaves only as a thermal resistor, a three-terminal conductor-insulator-conductor interface can function as an electricity generator caused by phonon-mediated electron scatterings with heat-charge current separation. Unlike conventional thermoelectrics which is a property of a bulk caused by the Seebeck effect, this thermoelectric behavior is a property of an interface driven by electron-phonon scatterings.

Peculiarities of inelastic scattering of light by nanoclusters

Nanocrystals of were produced during the process of combustion of the glycine-nitrate with precursors together with an excess amount of the oxidizing agent. X-ray diffraction patterns and Raman spectra were measured for investigation of the structure of the synthesized material. Hidden periodicities were extracted in the Raman spectra, using the example of two compounds with x = 0 and x = 0.2, correspondingly. In comparison with theory, the analysis showed that the distribution of the inverse periods revealed from the experiment results in the appearance of two narrow peaks common for both samples with maximums 0.014 and 0.01 cm (70 and 100 cm−1). The discovered effect is analyzed with the model of a combination of Raman- active oscillations from the nanoscale inelastic light scatterers with different shapes.