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The high brilliance of ultrashort X-ray pulses recently generated in free electron lasers will soon open the way to the investigation of non-linear processes that still remain inaccessible due to the smallness of the corresponding cross sections. One of them is stimulated Compton scattering from molecules. In this work, we investigate stimulated Compton scattering from fixed-in-space H2 molecules in the few-hundred eV photon energy range, where both dipole and non-dipole transitions are important. We show that the interference between dipole and non-dipole transitions leads to pronounced asymmetries in the electron angular distributions. These asymmetries strongly depend on molecular orientation, to the point that they can lead to electron emission in either the forward or the backward directions with respect to the propagation axis, or in both directions, or even in the orthogonal direction. This is in contrast with Compton scattering from free electrons or atomic targets. X-ray free electron lasers provide high brightness sources that permit the study of low-cross section phenomena, such as Compton scattering from atoms and molecules. Here, the angular distribution of electrons after stimulated Compton scattering from molecular hydrogen are simulated, revealing the influence of dipole and non-dipole transitions. [ABSTRACT FROM AUTHOR]

Repeated Compton scattering of photons with thermal electrons is one of the fundamental processes at work in many astrophysical plasma. Solving the exact evolution equations is hard and one common simplification is based on Fokker–Planck (FP) approximations of the Compton collision term. Here we carry out a detailed numerical comparison of several FP approaches with the exact scattering kernel solution for a range of test problems assuming isotropic media and thermal electrons at various temperatures. The Kompaneets equation, being one of the most widely used FP approximations, fails to account for Klein–Nishina corrections and enhanced Doppler boosts and recoil at high energies. These can be accounted for with an alternative FP approach based on the exact first and second moments of the scattering kernel. As demonstrated here, the latter approach works very well in dilute media, but inherently fails to reproduce the correct equilibrium solution in the limit of many scattering. Conditions for the applicability of the FP approximations are clarified, overall showing that the Kompaneets equation provides the most robust approximation to the full problem, even if inaccurate in many cases. We close our numerical analysis by briefly illustrating the solutions for the spectral distortions of the cosmic microwave background (CMB) after photon injection at redshift z  ≲ 105, when double Compton and Bremsstrahlung emission can be omitted. We demonstrate that the exact treatment using the scattering kernel computed with cspack is often needed. This work should provide an important step towards accurate computations of the CMB spectral distortions from high-energy particle cascades. [ABSTRACT FROM AUTHOR]

We perform calculations of nonequilibrium reaction rates for all triple interactions in relativistic plasma including: relativistic bremsstrahlung, double Compton scattering, radiative pair production, triple pair production/annihilation and their inverse processes. Reaction rates are computed out of first principles, numerically integrating exact QED matrix elements over the phase space of particles. Example is given for photon emission by hot thermal electron–positron pairs. [ABSTRACT FROM AUTHOR]

This article retraces different methods that have been explored to account for the atomic thermal motion in the reconstruction of one‐electron reduced density matrices from experimental X‐ray structure factors (XSF) and directional Compton profiles (DCP). Attention has been paid to propose the simplest possible model, which obeys the necessary N‐representability conditions, while accurately reproducing all available experimental data. The deconvolution of thermal effects makes it possible to obtain an experimental static density matrix, which can directly be compared with theoretical 1‐RDM (reduced density matrix). It is found that above a 1% statistical noise level, the role played by Compton scattering data becomes negligible and no accurate 1‐RDM is reachable. Since no thermal 1‐RDM is available as a reference, the quality of an experimentally derived temperature‐dependent matrix is difficult to assess. However, the accuracy of the obtained static 1‐RDM, through the performance of the refined observables, is strong evidence that the Semi‐Definite Programming method is robust and well adapted to the reconstruction of an experimental dynamical 1‐RDM. [ABSTRACT FROM AUTHOR]

We present the long-term X-ray spectral and temporal analysis of a 'bare-type AGN' Ark 120. We consider the observations from XMM–Newton, Suzaku, Swift , and NuSTAR from 2003 to 2018. The spectral properties of this source are studied using various phenomenological and physical models present in the literature. We report (a) the variations of several physical parameters, such as the temperature and the optical depth of the electron cloud, the size of the Compton cloud, and the accretion properties for the last 15 yr. The spectral variations are explained from the changes in the accretion dynamics; (b) the X-ray time delay between 0.2–2 and 3–10 keV light-curves exhibited zero-delay in 2003, positive delay of 4.71 ± 2.1 ks in 2013, and negative delay of 2.90 ± 1.26 ks in 2014. The delays are explained considering Comptonization, reflection, and light-crossing time; (c) the long-term intrinsic luminosities, obtained using nthcomp , of the soft-excess and the primary continuum show a correlation with a Pearson correlation coefficient of 0.90. This indicates that the soft-excess and the primary continuum originate from the same physical process. From a physical model fitting, we infer that the soft excess for Ark 120 could be due to a small number of scatterings in the Compton cloud. Using Monte Carlo simulations, we show that indeed the spectra corresponding to fewer scatterings could provide a steeper soft-excess power law in the 0.2–3 keV range. Simulated luminosities are found to be in agreement with the observed values. [ABSTRACT FROM AUTHOR]

Inter-crystal scattering (ICS) is a type of Compton scattering of photons from one crystal to adjacent crystals and causes inaccurate assignment of the annihilation photon interaction position in positron emission tomography (PET). Because ICS frequently occurs in highly light-shared PET detectors, its recovery is crucial for the spatial resolution improvement. In this study, we propose two different convolutional neural networks (CNNs) for ICS recovery, exploiting the good pattern recognition ability of CNN techniques. Using the signal distribution of a photosensor array as input, one network estimates the energy deposition in each crystal (ICS-eNet) and another network chooses the first-interacted crystal (ICS-cNet). We performed GATE Monte Carlo simulations with optical photon tracking to test PET detectors comprising different crystal arrays (8 × 8 to 21 × 21) with lengths of 20 mm and the same photosensor array (3 mm 8 × 8 array) covering an area of 25.8 × 25.8 mm2. For each detector design, we trained ICS-eNet and ICS-cNet and evaluated their respective performance. ICS-eNet accurately identified whether the events were ICS (accuracy > 90%) and selected interacted crystals (accuracy > 60%) with appropriate energy estimation performance (R2 > 0.7) in the 8 × 8, 12 × 12, and 16 × 16 arrays. ICS-cNet also exhibited satisfactory performance, which was less dependent on the crystal-to-sensor ratio, with an accuracy enhancement that exceeds 10% in selecting the first-interacted crystal and a reduction in error distances compared when no recovery was applied. Both ICS-eNet and ICS-cNet exhibited consistent performances under various optical property settings of the crystals. For spatial resolution measurements in PET rings, both networks achieved significant enhancements particularly for highly pixelated arrays. We also discuss approaches for training the networks in an actual experimental setup. This proof-of-concept study demonstrated the feasibility of CNNs for ICS recovery in various light-sharing designs to efficiently improve the spatial resolution of PET in various applications. [ABSTRACT FROM AUTHOR]

A feasible implementation of a novel X‐ray detector for highly energetic X‐ray photons with a large solid angle coverage, optimal for the detection of Compton X‐ray scattered photons, is described. The device consists of a 20 cm‐thick sensitive volume filled with xenon at atmospheric pressure. When the Compton‐scattered photons interact with the xenon, the released photoelectrons create clouds of secondary ionization, which are imaged using the electroluminescence produced in a custom‐made multi‐hole acrylic structure. Photon‐by‐photon counting can be achieved by processing the resulting image, taken in a continuous readout mode. Based on Geant4 simulations, by considering a realistic detector design and response, it is shown that photon rates up to at least 1011 photons s−1 on‐sample (5 µm water‐equivalent cell) can be processed, limited by the spatial diffusion of the photoelectrons in the gas. Illustratively, if making use of the Rose criterion and assuming the dose partitioning theorem, it is shown how such a detector would allow obtaining 3D images of 5 µm‐size unstained cells in their native environment in about 24 h, with a resolution of 36 nm. [ABSTRACT FROM AUTHOR]

Positron initiated deeply virtual Compton scattering (DVCS) off 4 He and 3 He nuclei is described. The way the so-called d - term could be obtained from the real part of the relevant Compton form factor is summarized, and the importance and novelty of this measurement is discussed. The measurements addressed for 3 He targets could be very useful even in a standard unpolarized target setup, measuring beam spin and beam charge asymmetries only. The unpolarized beam charge asymmetries for DVCS off 3 He and 4 He are also estimated, at JLab kinematics and, for 4 He, also at a configuration typical at the future Electron–Ion Collider. Incoherent DVCS processes, in particular the ones with tagging the internal target by measuring slow recoiling nuclei, and the unique possibility offered by positron beams for the investigation of Compton form factors of higher twist, are also briefly addressed. [ABSTRACT FROM AUTHOR]

An isotropic electromagnetic field in a plasma of thermalized electrons undergoes changes in energy as a result of Compton scattering and an Einstein–Hopf drag force on the electrons, eventually approaching a Bose–Einstein photon distribution at the electron temperature. The rate of change of field energy due to the combined effects of Compton scattering and the drag force is shown to be described by the Kompaneets equation for photon diffusion in frequency space. A similarity is noted between this approach and Einstein's derivation of the Planck spectrum based on the recoil of atoms as they absorb and emit radiation. [ABSTRACT FROM AUTHOR]

The impact of potential future measurements of beam charge asymmetries on the current knowledge of Compton form factors is evaluated. Elaborating on the results of a global neural network fit to deeply virtual Compton scattering data, a Bayesian reweighting analysis quantifies the improved determination of the real part of the Compton form factor H . Such an improvement is particularly relevant for the experimental determination of the proton mechanical properties or for universality studies of generalized parton distributions through analyses of virtual Compton scattering in both spacelike and timelike regions. [ABSTRACT FROM AUTHOR]

Double Deeply Virtual Compton Scattering (DDVCS) is the only experimental channel for the determination of the dependence of the Generalized Parton Distributions (GPDs) on both the average and the transferred momentum independently. The physics observables of the electron induced di-muon production reaction e → ± p → e ± p μ + μ - off unpolarized hydrogen are discussed. Their measurement with the high luminosity and large acceptance SoLID spectrometer at the Thomas Jefferson National Accelerator Facility, using polarized and unpolarized positron and electron beams at 11 GeV is investigated. This experimental configuration is shown to provide unprecedented access to the GPDs with the determination of the real and imaginary parts of the Compton Form Factor H in an unexplored phase space, and to enable an exploratory investigation of higher twist effects. [ABSTRACT FROM AUTHOR]

Measuring DVCS on a neutron target is a necessary step to deepen our understanding of the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). The combination of DVCS observables on neutron and proton targets allows to perform a flavor decomposition of the Compton Form Factors (CFFs), which are related to integrals of GPDs. Moreover, neutron-DVCS plays a complementary role to DVCS on a transversely polarized proton target in the determination of the CFF of the GPD E, the least known and constrained GPD that enters Ji's angular momentum sum rule. A measurement of the beam-charge asymmetry (BCA) in the e ± d → e ± n γ (p) reaction can significantly impact the experimental determination of the real CFFs of the E and, to a lesser extent, H ~ CFFs. [ABSTRACT FROM AUTHOR]

A compact broadband Compton spectrometer is designed to measure the continuous spectrum of gamma-ray sources driven by an intense laser. The incident gamma rays are converted into electrons in low-Z materials by Compton scattering. Produced by a pair of stepped magnets, a weaker-front–stronger-rear nonuniform magnetic field in the electron magnetic spectrometer is used to spectrally resolve the scattered electrons, leading to a broadband gamma-ray spectral coverage of 2–20 MeV in a compact volume. Flat imaging-plate detectors are placed near the focused imaging points of the magnetic spectrometer to record the dispersed electrons, thereby achieving an optimal spectral resolution of 6%–13% in the energy range of 3–20 MeV. The spectrometer is used successfully to measure the gamma-ray spectrum generated by the high-energy electron beams produced by a femtosecond-laser-driven wakefield. [ABSTRACT FROM AUTHOR]

We present a numerical model for calculation of spectra of synchrotron-self-Compton radiation sources, e.g., gamma-ray bursts and TeV blazars. The model implements sequential allowance of the Compton scattering and two-photon production of electron-positron pairs using precise quantum-electrodynamic expressions for the corresponding differential equations. The previously unknown phenomena revealed by using the model are discussed, and an example of modeling the actual spectrum observed in the afterglow of the GRB 190114C gamma-ray burst is presented. [ABSTRACT FROM AUTHOR]

Researchers have been searching for different methods to determine the effective atomic number of materials for many years. Therefore, there are many methods in the literature to determine the effective atomic number theoretically or experimentally. While theoretical methods neglect some parameters, such as the momentum transfer parameter, photon energy, or scattering angle, experimental methods have incommodious processes. The main goal of this study is to provide a practical simulation method that is both as realistic as experimental results and as easy as theoretical methods. The method considers all these parameters compared to other theoretical methods and transfers them to the virtual environment. In this study, Rayleigh and Compton scattering peaks of 60 pure elements (in the range 20< Z <80) were determined. Rayleigh and Compton peak ratios were correlated with their atomic numbers. The proposed method is available for any energy or scattering angle. Six different compounds (WC, W 65 Cu 35 , SnAg, Fe 54 Co 17 Ni 29 , Pd 94 Cr 6 , Cu 60 Zn 40) were selected from different atomic number regions (such as low, medium, and high regions). It is important to note that any material (compound or mixture) could be selected. Validation of the method has been performed via different methods commonly used in the literature. It is observed that the results of this method are in good agreement with other methods in the literature. We are expecting that the proposed method will provide great convenience and guidance to researchers in this area. • A Monte Carlo simulation method of the R/C scattering ratio were proposed to determine the effective atomic number. • The scattering spectra were measured for about sixty different pure elements with atomic numbers between 20 and 80. • The ratios of the R/C scattering peaks were correlated with their atomic numbers. • The proposed method was tested on six different compounds. • The validation of the proposed method was confirmed with the theoretical results. [ABSTRACT FROM AUTHOR]

X/γ-rays have many potential applications in laboratory astrophysics and particle physics. Although several methods have been proposed for generating electron, positron, and X/γ-photon beams with angular momentum (AM), the generation of ultra-intense brilliant γ-rays is still challenging. Here, we present an all-optical scheme to generate a high-energy γ-photon beam with large beam angular momentum (BAM), small divergence, and high brilliance. In the first stage, a circularly polarized laser pulse with intensity of 1022 W/cm2 irradiates a micro-channel target, drags out electrons from the channel wall, and accelerates them to high energies via the longitudinal electric fields. During the process, the laser transfers its spin angular momentum (SAM) to the electrons' orbital angular momentum (OAM). In the second stage, the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed. In the third stage, the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the γ-photons via nonlinear Compton scattering. Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ-ray beam is $\sim 1{0}^{22}$ photons·s–1·mm–2·mrad–2 per 0.1% bandwidth at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of $1{0}^6\hslash$ /photon. The AM conversion efficiency from laser to the γ-photons is unprecedentedly 0.67%. [ABSTRACT FROM AUTHOR]

Radiation is used in many applications such as medicine, therapy, industry but it also has some disadvantages or hazards. Therefore, the knowledge of how radiation interacts with matter becomes very important at different photon energies. In the present study, Compton mass attenuation coefficients of different types of materials were investigated via Klein-Nishina formula in the energy range 0.284–15 MeV. Different methods were used to determine Compton mass attenuation coefficients of the materials. The results were compared with each other in terms of the methods. According to the results, Klein-Nishina electronic cross-sections and Compton mass attenuation coefficients of the studied materials were decreased with increasing γ-ray energy like the elements. In addition, the results were compared with possible results from literature as the mean result of the study. A good agreement was observed for Zn, Sn, Te, Ba, W and Bi elements (Diff. ≤ 6.25%) at 1.173 MeV photon energy. Best agreement was also observed for ZnS and CaCO 3 compounds (0.14% ≤ Diff. ≤ 22.18%) at 4 and 1.332 MeV photon energies respectively. The reported data should be useful when the gamma rays into these materials especially in Compton scattering energy region. • CMACs of important materials were determined using Klein-Nishina theory. • Different methods were used to calculate CMACs. • The methods were especially performed at Compton scattering energy region. [ABSTRACT FROM AUTHOR]

• First-ever magnetic Compton profiles (MCPs) of non-stoichiometric Ni 0.9-x Pr x Fe 2.1 O 4 inverse spinel ferrites. • Decomposed experimental MCPs into constituent profiles of Ni, Fe, Pr-4f and diffuse electrons. • Validated MCP based total and site-specific spin moments using FP-LAPW calculations. • Explored role of orbital magnetic moments using MCP data and magnetization data. • Revealed effect of Pr-4f states in amending the spin moments and electronic properties. Magnetic Compton profiles of 5 % and 15 % Pr-doped non-stoichiometric NiFe 2 O 4 have been measured using synchrotron radiations of energy 182.65 keV at SPring-8, Japan. An analysis of MCPs measured at 6 and 300 K show that the total spin moment decreases with increasing temperature and Pr concentration in Ni 0.9-x Pr x Fe 2.1 O 4 which is consistent with the magnetic moment (spin + orbital) as observed from magnetization measurements data. Spin moments at different sites are deduced using decomposition of MCPs in the elemental profiles of Ni, Pr-4f, Fe and diffused electrons. Spin moments at Ni-site have been found to play crucial role in emergence of absolute spin moments. Spin moments at Pr-site is aligned antiparallel to that of Ni and Fe sites. The orbital magnetic moment is also deduced from the subtraction of MCP based spin moments from the magnetization data. Theoretical FP-LAPW based total and atom specific spin moments are found in consonance with the MCP based data. Total and spin projected density of states are also computed using the FP-LAPW method to validate role of Pr-4f and Fe-3d (O h) states in amending the total magnetic moment with Pr concentration. The M−H based saturation magnetization derived at 6 and 300 K temperature show that the saturation magnetic moments reduce from 2.21 → 2.05 μ B /f.u. at 6 K and 2.10 → 1.98 μ B /f.u. at 300 K with increase in Pr concentration from 5 % → 15 %. On the basis of hysteresis curve and coercive force, both the doped compounds show soft magnetism. [ABSTRACT FROM AUTHOR]

In high-energy-density physics, when the temperatures are high (keV-range) and/or the densities are low, Compton scattering becomes the main energy transfer mechanism between the radiation field and the material. The interaction between the radiation field and the material is non-linear in the radiation field – due to induced processes caused by photons being bosons – and in the material temperature. Many existing codes use a Compton-Fokker-Planck (CFP) approximation – which is inaccurate for high photon energies or material temperatures – or use linear approximations within a time-step. We have implemented a new Compton-heating method called OS-FBC (Operator-Split Full-Boltzmann Compton) that solves the full, nonlinear Compton-heating system with few approximations. • A method for computing radiation-material energy transfer with Compton scattering. • The method does not use the common Fokker-Planck approximation. • The method is operator-split and converges all non-linearities. • It is computationally efficient and performs similarly to other Compton methods. [ABSTRACT FROM AUTHOR]

• Coherent Compton scattering is due to interference of the incident and Bragg beams. • It probes non-diagonal terms in the momentum density matrix for solid-state electrons. • The conditions for a directly interpretable coherent Compton EELS signal are derived. • Experimental results are presented for silicon under 004 and 2 ¯ 20 diffraction conditions. Experimental techniques that probe the electronic structure of crystalline solids are vital for exploring novel condensed matter phenomena. In coherent Compton scattering the Compton signal due to interference of an incident and Bragg diffracted beam is measured. This gives the projected, non-diagonal electron momentum density of the solid, a quantity that is sensitive to both the amplitude and phase of the electron wavefunction. Here coherent electron Compton scattering is demonstrated using electron energy loss spectroscopy in the transmission electron microscope. The technique has several advantages over coherent X-ray Compton scattering, such as a superior spatial resolution and the use of smaller specimens to generate Bragg beams of sufficient intensity. The conditions for a directly interpretable coherent electron Compton signal are established. Results are presented for the projected, non-diagonal electron momentum density for silicon under 004 and 2 ¯ 20 Bragg beam set ups. [ABSTRACT FROM AUTHOR]

Positron emission particle tracking (PEPT) is used to study a wide range of scientific, industrial, and biomedical systems, typically those inaccessible through conventional optical particle tracking techniques. However, in dense or thick-walled systems a fraction of the coincident gamma-rays emitted from a PEPT tracer, called Lines-of-Response (LoRs), are attenuated via Compton scattering. Additionally, at high source activity, random LoRs may be formed by two unrelated events. The incorporation of scattered or random LoRs decreases PEPT spatial accuracy and can distort the trajectory. In this work, we use validation experiments and simulations to investigate the spatial accuracy of the Birmingham Method (BM) PEPT algorithm when two key free parameters are changed: the total number of LoRs in the sample and the fraction of LoRs in the sample used to locate the tracer. Our results show that the default algorithm parameters are not suitable for all cases, however, Monte Carlo simulations of PEPT experiments can be used to estimate the optimal parameter values. Ultimately a variant of the BM, called Dynamic-BM, is demonstrated in a virtual PEPT experiment. Dynamic-BM uses the optimal parameters on a sample-by-sample basis improving PEPT accuracy in this case by 4.03% over the best constant parameters and 76.5% over the default parameters. These improvements make PEPT a more accurate and thus more useful tool. • Two key free parameters a PEPT algorithm are optimised for spatial accuracy. • Optimal parameter values are discovered through experiments and simulations of PEPT. • The Birmingham Method is extended to dynamically change parameter values. • Using optimal values, spatial errors decrease by 76.5% compared to default values. [ABSTRACT FROM AUTHOR]

Aimed at progress in mega-electron volt (MeV) gamma-ray astronomy, which has not yet been well-explored, Compton telescope missions with a variety of detector concepts have been proposed so far. One of the key techniques for these future missions is an event reconstruction algorithm that is able to determine the scattering orders of multiple Compton scattering events and to identify events in which gamma rays escape from the detectors before they deposit all of their energies. We revisit previous event reconstruction methods and propose a modified algorithm based on a probabilistic method. First, we present a general formalism of the probabilistic model of Compton scattering describing physical interactions inside the detector and measurement processes. Then, we also introduce several approximations in the calculation of the probability functions for efficient computation. For validation, the developed algorithm has been applied to simulation data of a Compton telescope using a liquid argon time projection chamber, which is a new type of Compton telescope proposed for the GRAMS project. We have confirmed that it works successfully for up to 8-hit events, including correction of incoming gamma-ray energies for escape events. The proposed algorithm can be used for next-generation MeV gamma-ray missions featured by large-volume detectors, e.g., GRAMS. [ABSTRACT FROM AUTHOR]

• Measured spin momentum densities for Ni/Co doped LCMO using synchrotron radiations. • Elaborated peculiarities of magnetism using experimental MCPs and DFT computations. • Revealed mixed valence states of Mn and its ferromagnetic interaction with Ni and Co. • Explored Z-in and Z-out JT distortion in LCMO and after Ni and Co doping. • Disseminated guidelines for interpretation of MCP data using ab-initio computations. Magnetic Compton profiles (MCPs) of La 0.7 Ca 0.3 Mn 0.95 (Ni/Co) 0.05 O 3 between 8 and 250 K have been measured using high energy inelastic scattering at SPring-8, Japan. For a quantitative analysis on amendment of magnetic properties, temperature-dependent experimental MCPs are decomposed into constituent profiles related to Mn, Ni/Co and itinerant (diffuse) electrons. Decomposed profiles unambiguously show that Mn-3d electrons are ferromagnetically coupled with Ni/Co ions while itinerant electrons are linked anti-ferromagnetically with Mn-3d and Ni/Co-3d electrons. An annotation of MCP and VSM data depicts that the orbital magnetic moments are anti-ferromagnetically coupled to total spin moments. Variation in magnetic response in undoped and Ni/Co doped perovskites is devoted to formation of mixed valence states of Mn atom. The spin contribution at different sites are found to be in tune with present density functional theory (DFT) based calculations which are thoroughly analyzed on the basis of changes in the e g and t 2g states of Mn, Ni/Co caused by Jahn-Teller distortion. Present MCP data and DFT calculations set guidelines to probe the reliable origin to examine magnetic response and half-metallic properties of such manganites. [ABSTRACT FROM AUTHOR]

The PREX-2 and CREX experiments in Hall A at Jefferson Lab are precision measurements of parity violating elastic electron scattering from complex nuclei. One requirement was that the incident electron beam polarization, typically ≈ 90 % , be known with 1% precision. We commissioned and operated a Møller polarimeter on the beam line that exceeds this requirement, achieving a precision of 0.89% for PREX-2, and 0.85% for CREX. The uncertainty is purely systematic, accumulated from several different sources, but dominated by our knowledge of the target polarization. Our analysis also demonstrates the need for accurate atomic wave functions in order to correct for the Levchuk Effect. We describe the details of the polarimeter operation and analysis, as well as (for CREX) a comparison to results from a different polarimeter based on Compton scattering. [ABSTRACT FROM AUTHOR]

In this work, effective atomic numbers of some Fe–Ni alloys were obtained experimentally by coherent and Compton scattering intensity ratios at scattering angle of 168° by using Americium-241 gamma rays (59.54 keV) and High Purity Germanium Detector (HPGe) detector. The experimental setup consisting of Am-241 and HPGe detector was simulated using the MCNP (Version 6.2) code. The intensity ratios of coherent and Compton scattering peaks of Cr, Mn, Fe, Co, Ni, Cu and Zn elements used for calibration were plotted as a function of their atomic numbers. The effective atomic numbers of the investigated alloys were determined by the interpolation method based on the coherent to Compton scattering ratio. Coherent to Compton intensity ratios of the alloys ranged from 1098.02 to 1165.47. The effective atomic number values obtained by MCNP simulation of the alloys were between 26.423 and 27.211, the experimentally effective atomic number values were between 26.524 and 27.382, and the theoretical effective atomic number values obtained with ZXCom were between 26.710 and 27.594. It is observed that the results obtained by the simulation method are in agreement with the experimental results and the theoretical results obtained with ZXCOM. • Effective atomic numbers of some Fe– Ni alloys were obtained by experimental method. • The results were verified via MCNP (Version 6.2) simulation codes and ZXCOM program. • Zeff values and R/C ratios decrease with increasing iron concentration. [ABSTRACT FROM AUTHOR]

The two-tensor-pomeron model proposed previously to describe low x DIS data is applied to real and virtual Compton scattering on a proton. The model includes two tensor pomerons, a soft and a hard one, and tensor reggeons. We include contributions of both transverse and longitudinal virtual photons. We show that this model gives a very good description of experimental data at small Bjorken x on deeply virtual Compton scattering (DVCS) from HERA. The reggeon exchange term is particularly relevant for describing the real-photon-proton scattering measured at lower γp energies at FNAL. We present two fits which differ somewhat in the strength of the hard pomeron contribution. In both fits we find that the interference between soft- and hard-pomeron exchange plays an important role. We find that in DVCS the soft-pomeron contribution is considerable up to Q 2 ∼ 20 GeV2. Our model allows to study the transition from the small- Q 2 regime, including the photoproduction (Q 2 = 0) limit, to the large- Q 2 regime, the DIS limit. We also discuss the ratio of cross sections for longitudinally and transversely polarized virtual photons in γ ⁎ p → γ p as a function of | t | and Q 2. The ratio R ˜ (Q 2 , W 2 , t) = (d σ L / d t) / (d σ T / d t) strongly increases with t. Our findings may be checked in future lepton-nucleon scattering experiments in the low- x regime, for instance, at a future Electron-Ion Collider at the BNL (EIC), and, if LHeC is realized, at the LHC. [ABSTRACT FROM AUTHOR]

In this study, seven alloys with a nominal composition of (CuO 2) 0.5 M 0.5 (M = Fe, Co, Ni, Cu, Zn, Y, and Nb wt%) were produced via the powder mixed method. Alloys and pure metals were excited with 59.54 keV photon energy emitted from Am-241 radioactive source at 25°, 35°, 45°, 55°, 65°, 75′ and 85° scattering angles. The spectra of the coherent/Compton peaks were obtained by Si(Li) detector. First of all, chemical shift, (ΔE) peak energies, (E) asymmetry index (A s) and full width half maximum (FWHM) values were found in the Compton/Coherent scattering spectra obtained depending on the scattering angle and the chemical environment of the transition metals. Then the ratios of the Coherent/Compton scattering differential cross-section (dσ coherent /dσ Compton) were obtained experimentally. The experimental dσ coherent /dσ Compton ratios of the selected 3d-4d transition metals were found to be compatible with the data in the literature. Asymmetry and chemical shifts were observed in almost all samples, especially in Compton peaks, with increasing scattering angles. The chemical shifts of Compton and Coherent peaks of the alloys were found in the range of 1–932 eV. The experimental dσ koherent /dσ Compton ratios for the alloys obtained by adding Fe, Co, Ni, Cu, Zn, Y, and Nb to Cu 2 O were found as 0.697, 0.689 0.678, 0.698, 0.736, 0.755, 0.798, 0.835 at 45° scattering angle, respectively. It has been determined that the experimental dσ coherent /dσ Compton ratio for each alloy increases with increasing atomic number, while it decreases with increasing scattering angle. • (CuO 2) 0.5 M 0.5 (M = Fe, Co, Ni, Cu, Zn, Y, and Nb wt%) alloys were prepared via the powder mixed method. • Compton/Coherent scattering spectra were investigated depending on the scattering angle and chemical environment. • As, FWHM, E and ΔE parameters of the Compton/Coherent peak changed depending on the scattering angle. • As the atomic number of the metal added to the alloys increased, the dσ coherent /dσ Compton ratio enhanced. • The dσ coherent /dσ Compton ratio decreased with increasing scattering angle. [ABSTRACT FROM AUTHOR]

• GH shift is controlled and modified under the effects of Kerr nonlinearity, Doppler broadening and Compton scattering. • Maximum GH-shift in the reflection/transmission is investigated to ±3 λ. • Above, the ϕ c = π / 6 GH-shift is saturated at λ in the reflection. • GH-shift is the function of control fields, Kerr nonlinearity, Doppler broadening. • Gh-Shift changes with incident and Compton scattered angles. • The results have applications in nano-optics, trapping of optical data, micro-optics. Reflection, transmission as well as absorption coefficients and the corresponding Goos Hänchen shift in reflection and transmission is controlled and modified under the effects of Kerr nonlinearity, Doppler broadening as well as Compton scattering. The summation of the absolute values of these coefficients gives a unit value in the presence of all these effects. Modification of the coefficients follows the normalization condition. Maximum GH-shift in the reflection/transmission is investigated to ± 3 λ. Above ϕ c = π / 6 , the GH-shift is saturated at the value λ in both reflection/transmission. The positive as well as negative GH-shift is measured in the absence and presence of Compton scattered reflected/transmitted beam. The GH-shift is the function of control fields, Kerr nonlinearity, incoherent effect of Doppler broadening and incident as well as the Compton scattered angles. The results show potential applications in nano-optics, trapping of optical data, micro-optics, acoustics, sensor technology and plasma physics. [ABSTRACT FROM AUTHOR]

The radiation shielding, physical and optical properties were studied with the glass formula in the composition of xGd 2 O 3 : 40Na 2 O: 5SiO 2 : (55-x)B 2 O 3 , where x = 0, 2.5, 5, 7.5, 10, 12.5, 15 mol%, respectively. The gadolinium sodium borosilicate glasses were melted entirely by melt quenching technique at 1200oc. Gamma-ray shielding property was studied with Compton scattering technique from 0.224 MeV to 0.662 MeV gamma-ray energy range. The density and molar volume of the glass samples were increased with higher Gd 2 O 3 concentration. The glass samples show high transparency which can be observed from transmission spectra. The radiation shielding properties are better with increased Gd 2 O 3 concentrations. The results of total mass attenuation coefficient, the effective atomic number and the effective electron density showed the theoretical and experimental values are in good agreement and showed similar trends. The best shielding radiation properties were obtained at 15% of Gd 2 O 3 concentration. At 15% of Gd 2 O 3 concentration shows the same attenuation behavior with 0.64 mm of lead. The half value layer (0.662 MeV) at 15% of Gd 2 O 3 concentration is better than the commercial window, serpentine and ordinary concrete. • Gd 2 O 3 show highly effective for the radiation shielding material. • Radiation shielding properties investigated by using 137Cs. • WinXcom was used to compare the experimental values of shielding properties. • The HVL was inquired at 0.662 MeV gamma-ray energy. • The lead equivalent thickness obtained by 15 mol% of Gd 2 O 3 concentration. [ABSTRACT FROM AUTHOR]

Mammary neoplasms are the most common in female dogs, with high malignancy rates. Despite sharing many similarities with human breast tissues, the prevalence of this type of cancer in dogs are nearly three times higher. Taking that into account, this study aims to present preliminary results about chemical and structural changes occurring in samples of canine breast tumors. For this, we analyzed seven samples including normal, benign and malignant tissues, using micro X-ray fluorescence (μ -XRF) and Compton scattering technique. Our goal was to respectively map the spatial distribution of Fe, Cu and Zn and to determine the electron densities in selected regions of the samples. Results showed that Cu and Zn distributions were spatially correlated in normal tissues, with lower intensities in adipose regions and higher in the fibrous ones. Regarding benign neoplasms, both samples exhibited an increase in Cu intensity over the tumor area, however in different proportions. For the malignant ones, the presence of Fe was observed mostly in the tumor-adjacent regions. The electron density values obtained allowed to differentiate tissue structures, with generally higher density in tumorous regions and lower in adipose tissues. • Health and tumoral canine breast samples were analyzed using synchrotron radiation. • Micro-XRF and Compton scattering techniques were combined. • Micro-XRF provided the spatial distribution of Fe, Cu and Zn in the samples. • Compton scattering was sensitive to variations of electron densities in the samples. [ABSTRACT FROM AUTHOR]

The electron momentum densities of PbTi 1-x Zr x O 3 (x = 0, 0.4 and 1) measured using high energy 137Cs Compton spectrometer are reported. To validate the measurements, theoretical Compton profiles (CPs) and electronic structure of PbTi 1-x Zr x O 3 (x = 0, 0.4 and 1) are computed using the linear combination of atomic orbitals (LCAO) method. Differences between experimental and theoretical CPs unveil that the hybrid scheme (WC1LYP) is more applicable to account exchange and correlation energies in such materials than the other frequently used generalized gradient approximation (GGA) potentials. Experimental CPs based on scaling of equal-valence-electron-density show a more covalent character of PbTiO 3 than that of PbTi 0.6 Zr 0.4 O 3 and PbZrO 3 , which is in consonance with the present LCAO based Mulliken's population charge reorganization data. The density of states, dielectric constants, frequency-dependent absorption spectra and refractive indices are computed using the modified Becke-Johnson potential as incarnated in the full-potential augmented plane wave method. The present optical response suggests the possibility of using PbTi 1-x Zr x O 3 in the device for ultra-violet detection. • Compton profiles (CPs) of PbTi 1-x Zr x O 3 measured using 137Cs Compton spectrometer. • Uniquely compared measured CPs with LCAO data to suggest quantum models. • Explored nature of bonding in PbTi 1-x Zr x O 3 using CPs and LCAO-MP data. • Reported optical response and found use of materials in detection of UV-rays. [ABSTRACT FROM AUTHOR]

Electronic structure to judge trapping centres and activation energies in Mg-doped (2–8%) and Mg,Ti co-doped (2–3% each) LiF phosphors are presented using full-potential linearized APW method. Compton measurement for LiF is performed for appropriate choice of exchange-correlation potentials used in electronic properties. It is seen that 2–6% of Mg activator leads to formation of electronic traps with activation energy between 0.79 and 0.49 eV. At high concentration (>6%) of Mg, the formation of trap centres vanishes. Co-doping of 2% Mg,Ti permits the formation of trap centres, which is in contrast to higher concentrations. Mg-3s states play key role in the building of electronic trap centres. Higher concentration of Ti and Mg activators in LiF leads to the widening of 3d and 3s states, respectively. Analysis of optical response (frequency-dependent dielectric constants, trapping centres, and absorption coefficients) of 2% Mg-doped and 2% Mg,Ti co-doped LiF suggest their dosimetric applications and in ultra-violet detection. • Performed ab-initio calculations to explore the electronic and optical response of doped LiF. • Discussed electronic response in terms of electronic trap centres and the activation energies. • Explored formation of electronic traps in terms of widening of 3s and 3d states of Mg and Ti, respectively. • Optical properties of pure and doped LiF show applicability in ultra-violet detectors and dosimetry. • Reported experimental and DFT based momentum densities of pure LiF to validate potentials used. [ABSTRACT FROM AUTHOR]

We use a generalization of the Rosenbluth separation method for a model independent simultaneous extraction of the Compton Form Factors H and E , from virtual Compton scattering data on an unpolarized target. A precise evaluation of H and E , enabled by the proposed method, is the first step towards pinning down the distribution of angular momentum inside the proton. [ABSTRACT FROM AUTHOR]

We report here a theoretical proof of the limiting value of the velocity of target/particle responsible for various photon–electron interactions in the Compton scattering experiment which may be carried out in various applications such as gamma-ray spectroscopy. Compton scattering deals with the collision of photons with a target particle where both energy and momentum are transferred to the particle while the photon moves with reduced energy and a change of momentum. Here, the changed energy of a photon depends on the angle between the incident axis and scattered photon (θ), the rest mass of the electron, and the frequency of the photon before the collision. However, when some initial velocity is provided to an electron that is at rest initially, then in such cases, the particle obeys limiting value on velocity for a particular energetic photon to follow Compton scattering. In such cases, the changed frequency of photons also depends on the initial and final velocity of nonstationary electrons during a collision, including the angle (φ ′) between the recoil electron and incident axis. Here, we have presented the derivations to calculate the recoil velocity of the nonstationary electron. These terms are the accurate solution of the Compton shift. We have tried to calculate the upper limit or limiting values of the initial velocity of the target particle in Compton scattering. Further, we have computationally demonstrated that there is a dependence of scattered photon frequency on initial velocity of target particle (u) and mass of the target particle (m) at a higher scattering angle. Finally, numerical simulations were carried out with particles such as an electron, pion (+/-, 0) to verify the greater degree of accuracy of the particles in spectroscopic detectors such as gamma-ray spectroscopy and other high energy spectroscopic techniques. [ABSTRACT FROM AUTHOR]

We present a novel method to perform gamma-ray spectroscopy suitable for extreme pileup situations, wherein traditional pulse-height spectroscopy is infeasible or impractical. One example of such application is spectral characterization of intense laser-based radiation sources that employ laser wakefield acceleration, in which a large number of photons can be produced in a well-collimated beam on a picosecond or shorter timescale. The method relies on the angularly-resolved calorimetric measurement of Compton scattering. The probability for a photon to undergo Compton scattering into a given solid angle is a function of its energy and is described by the Klein–Nishina formula. By first Compton scattering the incident beam and then measuring the total energies deposited in multiple detectors placed at various scattering angles, the incident beam energy spectrum can be reconstructed without resolving the individual events in detectors. We compare the performance of an maximum likelihood expectation maximization algorithm with that of an artificial neural network to measure the energy spectrum of a beam of monoenergetic gamma rays from 137Cs decay. We demonstrate that the method can be used to reconstruct the characteristic inverse Compton scattering spectra. [ABSTRACT FROM AUTHOR]

The uncertainty of the energy measurement of the electron beam on circular electron positron collider (CEPC) must be smaller than 10 MeV to make sure the accurate measurement of the mass of the Higgs boson. In order to simplify the energy measurement system, a new method is proposed by fitting the Compton edge of the energy distribution of the gamma ray from a microwave–electron Compton scattering. With our method, the uncertainty of the energy measurement is 6 MeV for the electron energy of 120 GeV in the Higgs mode. In this system, the energy resolution of the gamma detection needs to reach 1 0 − 4 . Therefore, only the high-purity germanium (HPGe) detector can meet the critical requirement. In a head-on collision mode, the initial photons should be microwave photons with the wavelength of 3.04 centimeters. A cylindrical resonant cavity with selected T M 010 mode is used to transmit microwaves. After the microwave–electron Compton backscattering, the scattered photons and the synchrotron-radiation background transmit a shielding structure and then are detected by a HPGe detector at the end of the beam line of the synchrotron-radiation applications. The hole radius in the side wall of the cavity is about 1. 5 mm to allow the electron beam passing through. The results of the computer simulation technology (CST) software shows that the influence of the hole radius on the cavity field is negligible. The change of the resonance frequency can be easily corrected by fine-tuning the cavity size. [ABSTRACT FROM AUTHOR]

We present the momentum distributions of the nucleus and of the electrons from double ionization of the helium atom by Compton scattering of photons with hν=40 keV. We find that the doubly charged ion momentum distribution is very close to the Compton profile of the nucleus in the ground state of the helium atom, and the momentum distribution of the singly charged ion to give a precise image of the electron Compton profile. To reproduce these results, nonrelativistic calculations require the use of highly correlated initial- and final-state wave functions. [ABSTRACT FROM AUTHOR]

• A new method of dynamical spectroscopy. • Compton ionization of atoms. • Formulating conditions for new experiments. Recent experiments on single and double ionization of atoms by Compton scattering potentially open the door to establishing new methods of dynamical spectroscopy complementing the well-known methods like (e,2e) and (e,3e) spectroscopy. In this paper we explore the possibility to use double ionization of the helium atom by Compton scattering as a tool for direct spectroscopy of electron-electron correlations. For rather high photon energies of a few dozens of keV, a non-relativistic theoretical description of the process and the Kramers-Heisenberg-Waller approximation can be consistently used with a high computational efficiency. [ABSTRACT FROM AUTHOR]

Compact laser plasma accelerators generate high-energy electron beams with increasing quality. When used in inverse Compton backscattering, however, the relatively large electron energy spread jeopardizes potential applications requiring small bandwidths. We present here a novel interaction scheme that allows us to compensate for the negative effects of the electron energy spread on the spectrum, by introducing a transverse spatial frequency modulation in the laser pulse. Such a laser chirp, together with a properly dispersed electron beam, can substantially reduce the broadening of the Compton bandwidth due to the electron energy spread. We show theoretical analysis and numerical simulations for hard X-ray Thomson sources based on laser plasma accelerators. [ABSTRACT FROM AUTHOR]

A setup of a unique x-ray source is put forward employing a relativistic electron beam interacting with two counterpropagating laser pulses in the nonlinear few-photon regime. In contrast to Compton scattering sources, the envisaged x-ray source exhibits an extremely narrow relative bandwidth of the order of 10-4, comparable with an x-ray free-electron laser. The brilliance of the x rays can be an order of magnitude higher than that of a state-of-the-art Compton source. By tuning the laser intensities and the electron energy, one can realize either a single peak or a comblike x-ray source of around keV energy. The laser intensity and the electron energy in the suggested setup are rather moderate, rendering this scheme compact and tabletop size, as opposed to x-ray free-electron laser and synchrotron infrastructures. [ABSTRACT FROM AUTHOR]

We present the first measurement of the timelike Compton scattering process, γp→p′γ*(γ*→e+e-), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25

The relaxation of a photon bath to thermal equilibrium via Compton scattering with electrons is described in the Kompaneets equation (1957). The equation is mostly known from studies of astrophysical plasmas, for its convergence to the Planck distribution and for possible corrections to that Planck law in the cosmic microwave background, most notably from the Sunyaev–Zeldovich effect. We revisit its derivation emphasizing its structure as a Kramers–Moyal diffusion approximation to the quantum Boltzmann equation or Master equation with stimulated emission. We do not assume that the Planck law is stationary in performing the continuum approximation but we emphasize the necessity of the flux or Møller factor to arrive at a continuity equation. On the other hand, the structure allows more general assumptions than originally envisioned by Kompaneets. [ABSTRACT FROM AUTHOR]

We propose PET scanners using low atomic number media that undergo a persistent local change of state along the paths of the Compton recoil electrons. Measurement of the individual scattering locations and angles, deposited energies, and recoil electron directions allows using the kinematical constraints of the 2-body Compton scattering process to perform a statistical time-ordering of the scatterings, with a high probability of precisely identifying where the gamma first interacted in the detector. In these cases the Line-of-Response is measured with high resolution, determined by the underlying physics processes and not the detector segmentation. There are multiple such media that act through different mechanisms. As an example in which the change of state is quantum-mechanical through a change in molecular configuration, rather than thermodynamic, as in a bubble chamber, we present simulations of a two-state photoswitchable organic dye, a 'Switchillator', that is activated to a fluorescent-capable state by the ionization of the recoil electrons. The activated state is persistent, and can be optically excited multiple times to image individual activated molecules. Energy resolution is provided by counting the activated molecules. Location along the LOR is implemented by large-area time-of-flight MCP-PMT photodetectors with single photon time resolution in the tens of ps and sub-mm spatial resolution. Simulations indicate a large reduction of dose. [ABSTRACT FROM AUTHOR]

In this study, the photon interaction and the electron nonproportional response of Cs 2 LiYCl 6 :Ce (CLYC) scintillation were studied. The radioactive source of 137Cs that irradiated gamma rays with an energy of 662 keV were used in this experiment. For photon interaction, the mass attenuation coefficient (μ / ρ), the effective atomic number (Z e f f ) and the electron density (N e l ) were measured with eight different gamma ray energies using Compton scattering technique. For nonproportional response, the coincidence electron energy spectra were recorded at seven scattering angles of 30°–120° using Compton coincidence technique. The values of μ / ρ , Z e f f and N e l show decrease with the increasing of gamma ray energies. The nonproportional show that the CLYC demonstrated good proportional property all in the electron energy range of 99.24–450.59 keV. • CCT of CLYC crystal was studied for electron respond. • Zeff of CLYC has higher than of GAGG and CMO crystals. • Result show good proportionality from 200 keV up to 450.59 keV. [ABSTRACT FROM AUTHOR]

The spectrum of laser–plasma generated X-rays is very important, it characterizes electron dynamics in plasma and is basic for applications. However, the accuracies and efficiencies of existing methods to diagnose the spectrum of laser–plasma based X-ray pulse are not very high, especially in the range of several hundred keV. In this study, a new method based on electron tracks detection to measure the spectrum of laser–plasma produced X-ray pulses is proposed and demonstrated. Laser–plasma generated X-rays are scattered in a multi-pixel silicon tracker. Energies and scattering directions of Compton electrons can be extracted from the response of the detector, and then the spectrum of X-rays can be reconstructed. Simulations indicate that the energy resolution of this method is approximately 20% for X-rays from 200 to 550 keV for a silicon-on-insulator pixel detector with 12 μ m pixel pitch and 500 μ m depletion region thickness. The results of a proof-of-principle experiment based on a Timepix3 detector are also shown. [ABSTRACT FROM AUTHOR]

A new electromagnetic calorimeter consisting of 140 lead tungstate (PbWO 4) scintillating crystals was constructed for the PrimEx- η experiment at Jefferson lab. The calorimeter was integrated into the data acquisition and trigger systems of the GlueX detector and used in the experiment to reconstruct Compton scattering events. The experiment started collecting data in the spring of 2019 and acquired about 30% of the required statistics. The calorimeter is a prototype for two PbWO 4 -based detectors: the Neutral Particle Spectrometer (NPS) and the lead tungstate insert of the Forward CALorimeter (FCAL) of the GlueX detector. The article presents the design and performance of the Compton calorimeter and gives a brief overview of the FCAL and NPS projects. [ABSTRACT FROM AUTHOR]

Shanghai laser electron gamma source (SLEGS) is an energy-variable gamma-ray source developed based on the inverse Compton scattering of 10640 nm photons from a 100 W CO 2 laser on 3.5 GeV electrons from the Shanghai Light Source. It produces gamma-rays in the energy range of 0.4–21.7 MeV with a flux of 10 5 –10 7 photons/s. A collimator system was designed to produce quasimonochromatic gamma-ray beams with a best possible bandwidth of 1.1%–4.4% and filter out the substandard gamma-rays. The collimator system composed of coarse and fine collimators, constitutes a critical component of the SLEGS. By Geant4 simulations, we show that the collimator system is effective in tuning beam bandwidths and regular dodecagonal beam spots at the target position. [ABSTRACT FROM AUTHOR]

Experimental protocols aiming at the characterisation of glass transition often suffer from ambiguity. The ambition of the present study is to describe the glass transition in a complex, micro heterogeneous system, the dry rice pasta, in a most unambiguous manner, minimising the influence of technique-specific bias. To this end, we apply an unprecedented combination of experimental techniques. Apart from the usually used NMR and DSC, we employ, in a concurrent manner, neutron transmission, diffraction, and Compton scattering. This enables us to investigate the glass transition over a range of spatio-temporal scales that stretches over seven orders of magnitude. The results obtained by neutron diffraction and DSC reveal that dry rice pasta is almost entirely amorphous. Moreover, the glass transition is evidenced by neutron transmission and diffraction data and manifested as a significant decrease of the average sample number density in the temperature range between 40 and 60 °C. At the microscopic level, our NMR, neutron transmission and Compton scattering results provide evidence of changes in the secondary structure of the starch within the dry rice pasta accompanying the glass transition, whereby the long-range order provided by the polymer structure within the starch present in the dry rice pasta is partially lost. [ABSTRACT FROM AUTHOR]