Compton Scattering Research Articles

Improving HAWC dark matter constraints with inverse-Compton emission

Improving HAWC dark matter constraints with inverse-Compton emission

Holmium ions influence in structural and optical properties of Aluminium Strontium-phosphate glasses for radiation shielding applications

This study details the synthesis of a novel series of Holmium-doped Aluminium Strontium-phosphate glass (HoAlSr- phosphate glass) composed of 55 P2O5 + 5 Al2O3 + 4 MgO + 5 NaF + 10 LiCO3 + 5 CaO + 10 SrCO3 + 5 ZnO + 1 Ho2O3 prepared by melt-quench method and its structural, optical, and physical properties are analysed. Powder −XRD verified its amorphous nature, FTIR shows the existence of large phosphate functional groups, Optical properties such as band gap energy was calculated by acquiring absorption spectra covering the UV, Vis, and NIR ranges. Obtained 3.02 eV optical band gap energy. The refractive index changing with increasing energy. Three peaks in the PL spectra corresponded to Ho3+ transitions: 5I8→ 5G6, 5I8→ 3K8, and 5I8→ 5F3. The glass conducted theoretical studies for radiation shielding properties based on several key parameters. Gamma radiation shielding parameters, including Mean Free path (MFP), Effective atomic number (Zeff), linear attenuation coefficient (LAC), and mass attenuation coefficient (MAC), were obtained with the use of the Phy-X program. MAC data show that when Compton scattering (CS) fluctuates in the intermediate photon energy zone (E > 3 MeV), the area of prominence of CS diminishes. They can cause pair production at higher energies, Compton scattering at intermediate energies, and the photoelectric effect at lower energies. The MFP values of glasses doped with HoAlSr- phosphate glass were shorter, indicating a higher level of shielding efficacy. In this study we are focusing on optical properties changes with presence of Holmium ions and its shielding property using Phy-x software. In this research discovered that the synthetic material has high shielding qualities and can be a valuable shield in environments where X-rays are present. So it will be beneficial at X-ray prompted environment

Quantum Entanglement Filtering: A PET feasibility study in imaging dual-positron and prompt gamma emission via Monte Carlo simulation.

In this article, we investigate quantum entanglement (QE) filtering to address the challenges in multi-isotope positron emission tomography (PET) or in PET studies utilizing radiotracers with dual- positron and prompt gamma emissions. Via GATE simulation, we demonstrate the efficacy of QE filtering using a one-of-a-kind cadmium zinc telluride (CZT) PET system - establishing its viability as a multimodal scanner and ability to perform QE filtering. We show the high Compton scattering probability in this CZT-based scanner with 44.2% of gammas undergoing a single scatter prior to absorption. Additionally, the overall system sensitivity as a standard PET scanner (11.29%), QE-PET scanner (6.81%), and Compton Camera (11.29%) is quantified. Further, we find a 23% decrease in the double Compton scatter (DCSc) frequency needed for QE filtering for each mm decrease in crystal resolution and an increase in mean absolute error (MAE) of their Δϕs from 6.8° for 1 mm resolution to 9.5° , 12.2° , and 15.3° for 2, 4, and 8 mm resolution, respectively. These results reinforce the potential of CZT detectors to lead next generation PET systems taking full advantage of the QE information of positron annihilation photons.

Role of the Coulomb Potential in Compton Scattering.

We report a fully differential study of ionization of the Ne L shell by Compton scattering of 20keV photons. We find two physical mechanisms that modify the Compton-electron emission. Firstly, we observe scattering of the Compton electrons at their parent nucleus. Secondly, we find a distinct maximum in the electron momentum distribution close-to-zero momentum that we attribute to a focusing of the electrons by the Coulomb potential.

Revisit the γ-ray flare associated with blazar Mrk 421

Abstract A Very High-energy (VHE) flare was observed by Major Atmospheric Gamma
 Imaging Cherenkov Telescopes (MAGIC) on MJD 57788. This VHE flare was characterized
 by increased VHE flux and short timescales. In this study, we used one-zone synchrotron
 self-Compton (SSC), two-zone, and Spine/Layer models to explore this VHE flare’s origin.
 The results indicate that this γ-ray flare can be explained by Inverse Compton Scattering
 (ICS) radiation from the layer contributed gamma radiation and results in the γ-ray flare in a
 different way than the two-zone model. The difference between the two models lies in the
 performance of spectral energy distribution (SED) after γ-ray flare as well as a possible
 difference in the time scale of the flare.

Unveiling Doppler effects and charge phenomena in the elastic scattering of keV electrons on polystyrene

Recoil energy is a phenomenon that is observed in various spectroscopy experiments. Elastic Peak Electron Spectroscopy (also known as Electron Compton Scattering) studies the shape of the elastic peak resulting from electron scattering from solid targets. As the atoms move around their equilibrium position, they scatter the distribution of recoil energies, resulting in a broadening of the elastic peak known as Doppler broadening. Since the hydrogen peak has the largest recoil energy shifts due to the low mass of hydrogen, Elastic Peak Electron Spectroscopy is ideal for the detection of hydrogen. The most important aspects of this method for the detection of hydrogen include electron-induced hydrogen desorption and, in dielectric materials, charge phenomena. This work focuses on the elastic peak spectra of keV electrons impinging on polystyrene, with particular interest in the changes in line shape due to the Doppler effect and surface charge during electron irradiation.

Monte Carlo simulation code for polarized inverse Compton scattering sources

Polarized x rays or gamma rays generated from inverse Compton scattering (ICS) sources are high-brightness, quasimonochromatic, and polarization-tunable and are widely applied in medical imaging, material science, and nuclear physics research. In this paper, to simulate ICS between electron beams and polarized laser beams, a Monte Carlo simulation code has been developed and implemented based on the 4 toolkit. This code considers the polarization as well as the bandwidth of incident laser beams. The code is benchmarked by comparing its simulation results with those from the well-known Monte Carlo tool called and experimental results. The comparisons show that this code accurately reproduces the scattered photons, demonstrating its potential for various ICS-based applications. Published by the American Physical Society 2024

Full inverse Compton Scattering: Total transfer of energy and momentum from electrons to photons

In this article we discuss a peculiar regime of Compton Scattering that assures the maximum transfer of energy and momentum from free electrons propagating in vacuum to the scattered photons. We name this regime Full Inverse Compton Scattering (FICS) because it is characterized by the maximum and full energy loss of the electrons in collision with photons: up to 100% of the electron kinetic energy is indeed transferred to the photon. In the case of relativistic electrons, characterized by a large Lorentz factor (γ≫1), FICS regime corresponds to an incident photon energy equal to mec22, i.e. approximately 255.5 keV. We interpret such an astonishing result as FICS being the time reversal of direct Compton Scattering of very energetic photons (of energy much greater than mec2) onto atomic electrons. Although the cross section of Compton scattering is decreasing with the energy of the incident photon, making the process less probable with respect to other reactions (pair production, nuclear reactions, etc.) when high energetic photons are bombarding a target, the kinematics straightforwardly implies that the back-scattered photons would have an energy reaching asymptotically mec22. FICS is instead the unique suitable working point in Compton scattering for achieving the total transfer of (kinetic) energy exactly from the electron to the photon. Experiencing transitions from the initial momentum to zero in the laboratory system, in FICS the electron is also subject to very large negative acceleration; this fact can lead to possible experiments of sensing the Unruh temperature and related photon bath. On the other side of the energy dynamic range, low relativistic electrons can be completely stopped by moderate energy photons (tens of keV), leading to full exchange of temperature between electron clouds and photon baths. Cosmic gamma ray sources can be affected in their evolution by this peculiar FICS regime of Compton scattering.

Nonlinear scintillation effects in the intrinsic luminescence from Sc1.318Y0.655Si1.013O4.987 crystal excited by electrons and γ-quanta

The spectral and kinetic properties of intrinsic luminescence from (Y2Sc1)0.(3)(Sc)[Si]O5 crystal are studied. The emission is excited by electrons and γ-quanta. The composition (Y2Sc1)0.(3)(Sc)[Si]O5 is the congruent one for Sc2SiO5-Y2SiO5 solid solutions. It is found, that the crystal emits fairly bright intrinsic cathodololuminescence (CL) and radioluminescence (RL) at room temperature. In particular, the light yield of scintillation excited by γ-quanta with the energies of 661.7 keV is of 12000 photons/MeV. An increase in the beam flux by ∼20 times leads to the shift in the maximal CL energy spectral density from 315 to 340 nm and to the decrease in the CL decay time at 415 nm from 1377 ± 3 ns to 1165 ± 1 ns. Simultaneously, the decay time of RL excited by a photoelectron with the energy of 644.7 keV is of 1310 ± 10 ns while a Compton electron with the energy of 477 keV excites RL with the decay time of 1050 ± 10 ns. Also, we observed differences in the CL yield dependencies on the volume-averaged density of electronic excitations (EEs) at different wavelengths. An explanation of the results is given considering the nonlinear scintillation phenomena induced by an interaction between EEs. It is based on a conception that an increase in EE volume density leads to an increase in EEs nonradiative quenching due to these interactions.

Multiwavelength Investigation of γ-Ray Source MGRO J1908+06 Emission Using Fermi-LAT, VERITAS and HAWC

This paper investigates the origin of the γ-ray emission from MGRO J1908+06 in the GeV–TeV energy band. By analyzing the data collected by the Fermi Large Area Telescope, the Very Energetic Radiation Imaging Telescope Array System, and High Altitude Water Cherenkov, with the addition of spectral data previously reported by LHAASO, a multiwavelength study of the morphological and spectral features of MGRO J1908+06 provides insight into the origin of the γ-ray emission. The mechanism behind the bright TeV emission is studied by constraining the magnetic field strength, the source age, and the distance through detailed broadband modeling. Both spectral shape and energy-dependent morphology support the scenario that inverse Compton emission of an evolved pulsar wind nebula associated with PSR J1907+0602 is responsible for the MGRO J1908+06 γ-ray emission with a best-fit true age of T = 22 ± 9 kyr and a magnetic field of B = 5.4 ± 0.8 μG, assuming the distance to the pulsar d PSR = 3.2 kpc.

Development of a Monte Carlo simulation platform for the systematic evaluation of photon-counting detector-based micro-CT

PurposeThis study aimed to develop a photon-counting detector (PCD) based micro-CT simulation platform for assessing the performance of three different PCD sensor materials: cadmium telluride (CdTe), gallium arsenide (GaAs), and silicon (Si). The evaluation encompasses the components of primary and scatter signals, performance of imaging contrast agents, and detector efficiency. MethodsSimulations were performed using the Geant4 Monte Carlo toolkit, and a micro-PCD-CT system was meticulously modeled based on realistic geometric parameters. Results.The simulation can obtain HU values consistent with measured results for iodine and calcium hydroxyapatite contrast agents. The two major components of scatter signals for CdTe and GaAs based PCD are fluorescent X-ray photons and photoelectrons, whereas for Si, the components are photoelectrons and Compton electrons. Scattering counts of CdTe and GaAs sensors can be effectively reduced by using energy thresholds, whereas those of Si sensor are insensitive to the applied threshold. The optimal threshold values for CdTe and GaAs are 30 and 15 keV, respectively. For contrast agent imaging, GaAs exhibits enhanced sensitivity to low photon energies compared to CdTe, while it’s contrast-to-noise ratio (CNR) values are slightly lower than those of CdTe at the same contrast agent concentration. Among the three sensor materials, Si has the lowest CNR and detector efficiency; CdTe exhibits the highest efficiency, except in low-energy ranges (< 45 keV), where GaAs has superior efficiency. ConclusionsThe proposed methods are expected to benefit PCD optimization and applications, including energy threshold selection, scattering correction, and may reduce the need for large-scale experiments.

Theoretical Modeling of the Exceptional GRB 221009A Afterglow

The extraordinary gamma-ray burst GRB 221009A provides a great opportunity to investigate the enigmatic origin and evolution of gamma-ray bursts (GRBs). However, the complexity of the observations associated with this GRB provides significant challenges to developing a theoretical modeling in a coherent framework. In this paper, we present a theoretical interpretation of the GRB 221009A afterglow within the relativistic fireball scenario, aiming to describe the broadband data set with a consistent model evolution. We find that the adiabatic fireball evolution in the slow-cooling regime provides a viable scenario in good agreement with observations. Crucial to our analysis is the set of simultaneous GeV and TeV gamma-ray data obtained by AGILE and LHAASO during the early afterglow phases. Having successfully modeled as inverse Compton emission the high-energy spectral and lightcurve properties of the afterglow up to 104 s, we extend our model to later times when also optical and X-ray data are available. This approach results in a coherent physical framework that successfully describes all observed properties of the afterglow up to very late times, approximately 106 s. Our model requires time-variable microphysical parameters, with a moderately increasing efficiency ε e of a few percent for transferring the shock energy to radiating particles and a decreasing efficiency for magnetic field generation ε B in the range 10−5–10−7. Fitting the detailed multifrequency spectral data across the afterglow provides a unique test of our model.

Re-assessing special aspects of Dirac fermions in presence of Lorentz-symmetry violation

This paper focuses on additional inspections concerning the fermionic sector of the Standard Model Extension (SME). In this context, our main effort in this contribution is to investigate effects of Lorentz-symmetry violation (LSV) on the Klein Paradox, the Zitterbewegung and its phenomenology in connection to Condensed Matter Physics, Atomic Physics, and Astrophysics. Finally, we discuss a particular realization of LSV in the Dirac equation, considering an asymmetry between space and time due to a scale factor present in the linear momentum of the fermion, but which does not touch its time derivative. We go further and extend the implications of this asymmetry in the situation the scale factor becomes space–time dependent to compute its influence on the kinematics of the Compton effect with the extended dispersion relation for the fermion that scatters the photon.

A Compton scattering background subtraction method of gamma energy spectrum based on Gaussian function convolution

Due to the influence of the Compton effect and the relatively close gamma energy emitted during certain nuclide decays, gamma-ray spectrum analysis often faces challenges, such as a high count of Compton scattering continuum and overlapping peaks, which leading to some errors in energy spectrum analysis and low nuclide identification rates. This study proposes a spectrum analysis technique that uses Gaussian convolution to effectively eliminate background counts induced by Compton scattering. To minimize calculation errors in variance, the variance error is decreased from 2.98% to 0.84% through the utilization of a binary method for adjusting the transformation scale. Simulation results show that the average relative error of peak area calculations is less than 10.78%, and in the range of signal to noise ratio (SNR) greater than 22.5 dB, the differences between the standard peak center position and the peak center position measured by the Gaussian convolution method are less than 0.049%. The measured spectrum experiments were also carried out to confirm that the average relative error of peak area calculation is around 7.63%, and the relative error between the Gaussian convolution method and Gamma Vision peak-seeking result is around 0.18%. These results demonstrate that this method can effectively eliminate the Compton scattering background counts in the gamma spectrum, obtain the peak position and peak area of the full energy peak, and facilitate the accurate identification of the weak peak in the gamma spectrum.

Simulation Study on Attosecond Inverse Compton Scattering Source from Laser Wakefield Acceleration with Near-Threshold Ionization Injection

We present the generation of attosecond gamma rays via inverse Compton scattering within the framework of laser wakefield acceleration through 2D Particle-In-Cell simulations. Utilizing the near-threshold ionization injection mechanism, an attosecond micro-bunched electron beam characterized by a comb-like current density profile can be achieved with a linearly polarized laser at an intensity of a0 = 1.5. The micro-bunched beam provides a beam energy of approximately 300 MeV and achieves a minimum relative energy spread of about 1.64% after undergoing 2 mm of acceleration. In the inverse Compton scattering scheme, these attosecond electron micro-bunches interact with the reflected driving laser pulse, resulting in the attosecond gamma-ray radiation exhibiting similar structures. Individual spatial-separated gamma-ray pulses exhibit a length of approximately 260–300 as, with a critical energy of 2.0 ± 0.2 MeV. The separated attosecond gamma-ray source owns a peak brilliance of ~1022 photons s−1 mm−2 mrad−2 0.1% BW. This brilliance is competitive in a laboratory for multi-MeV γ-ray sources with a laser intensity of I = 5 × 1018 W/cm2. Such attosecond gamma-ray radiation offers promising applications requiring ultrashort X-ray/gamma ray sources.

Coherent Inverse Compton Scattering in Fast Radio Bursts Revisited

Growing observations of temporal, spectral, and polarization properties of fast radio bursts (FRBs) indicate that the radio emission of the majority of bursts is likely produced inside the magnetosphere of its central engine, likely a magnetar. We revisit the idea that FRBs are generated via coherent inverse Compton scattering (ICS) off low-frequency X-mode electromagnetic waves (fast magnetosonic waves) by bunches at a distance of a few hundred times the magnetar radius. The following findings are revealed: (1) Crustal oscillations during a flaring event would excite kHz Alfvén waves. Fast magnetosonic waves with essentially the same frequency can be generated directly or be converted from Alfvén waves at a large radius, with an amplitude large enough to power FRBs via the ICS process. (2) The cross section increases rapidly with radius and significant ICS can occur at r ≳ 100R ⋆ with emission power much greater than the curvature radiation power but still in the linear scattering regime. (3) The low-frequency fast magnetosonic waves naturally redistribute a fluctuating relativistic plasma in the charge-depleted region to form bunches with the right size to power FRBs. (4) The required bunch net charge density can be sub-Goldreich–Julian, which allows a strong parallel electric field to accelerate the charges, maintain the bunches, and continuously power FRB emission. (5) This model can account for a wide range of observed properties of repeating FRB bursts, including high degrees of linear and circular polarization and narrow spectra as observed in many bursts from repeating FRB sources.

Likely Detection of GeV γ-Ray Emission from Pulsar Wind Nebula G32.64+0.53 with Fermi-LAT

Abstract In this study, we report the likely GeV γ-ray emissions originating from the pulsar PSR J1849-0001's pulsar wind nebula (PWN) G32.64+0.53. Our analysis covers approximately 14.7 yr of data from the Fermi Large Area Telescope Pass 8. The position of the source and its spectrum matches those in X-ray and TeV energy bands, so we propose that the GeV γ-ray source is indicative of PWN G32.64+0.53. We interpret the broadband spectral energy distribution (SED) using a time-dependent one-zone model, which assumes that the multiband nonthermal emission of the target source can be generated by synchrotron radiation and inverse Compton scattering (ICS) of the electrons/positrons. Our findings demonstrate that the model substantially elucidates the observed SED. These results lend support to the hypothesis that the γ-ray source originates from the PWN G32.64+0.53 powered by PSR J1849-0001. Furthermore, the γ-rays in TeV bands are likely generated by electrons/positrons within the nebula through ICS.

Deep learning based Compton backscatter imaging with scattered X-ray spectrum data: A Monte Carlo study

Compton backscatter imaging (CBI) is a non-destructive testing (NDT) technique with the Compton effect. In CBI, the radiation source and detector are positioned on the same side of the object, which means that the imaging is almost not limited by the size of the object. The characteristic of single-sided imaging gives CBI substantial potential for applications in specific scenarios. In field archaeology, CBI can rapidly acquire subsurface images with the millimeter-level resolution, effectively enhancing archaeological excavation efficiency while better protecting artifacts. Therefore, CBI offers substantial potential in archaeological excavation. To address the problem of severe noise in CBI, we employed a scintillation detector to receive backscattered X-rays. Transformers directly reconstruct multi-channel projections to swiftly and accurately obtain precise reconstruction images. Monte Carlo simulation experiments confirm this method’s suitability for detecting a variety of common archaeological materials. Experimental results indicate that compared with count mode, multi-channel projections can effectively improve the reconstruction quality of CBI. Moreover, CBI can clearly image various materials of buried artifacts, proving the method’s versatility and practical value in NDT field.

Structural evolution of zirconium diboride under gamma irradiation and thermal annealing

Understanding the thermal properties and enhancing the performance of zirconium diboride (ZrB2) under extreme conditions is crucial, especially given its role as a burnable absorber in nuclear fuel pellets and its potential applications in accident-tolerant fuels. This study explores the structural alterations of ZrB2 crystals induced by gamma irradiation and subsequent thermal annealing. ZrB2 crystals were exposed to absorption doses of 300 kGy, 1000 kGy, 1500 kGy, and 3000 kGy using a 60Co gamma source, followed by thermal treatment at 1173 K under vacuum conditions. Also, Monte Carlo simulations were utilized to analyze the energy deposition and distribution of gamma quanta within the material during irradiation, highlighting Compton effects up to 0.23 MeV. X-ray diffraction analysis elucidated the impact of gamma radiation on ZrB2 crystal lattice parameters, space group, and volume expansion coefficient. Post-irradiation analysis revealed a maximum degree of amorphization and investigated mechanisms governing lattice parameter expansion. Thermal annealing at 1173 K significantly enhanced crystallinity, reducing amorphization to 0.2 % at an absorption dose of 3000 kGy and facilitating the restoration of the crystal's columnar structure. This comprehensive investigation provides insights into the intricate interplay between gamma irradiation, thermal processing, and resulting structural changes in ZrB2 nanocrystals, essential for applications in radiation-exposed environments.

Mitochondria-targeting nanozyme for catalytical therapy and radiotherapy with activation of cGAS-STING

BackgroundOvercoming radio-resistance and enhance radio-sensitivity to obtain desired therapeutic outcome plays an important role in treating cancer. MethodsHere we constructed a versatile enzyme-like nano-radiosensitizer MDP. MDP is composed of MnCO decorated and Ru-based nanozyme with triphenylphosphine (TPP) group coordinated on the surface. ResultsDue to the mitochondria-targeting ability of TPP and enhanced permeability and retention effect (EPR) effect of MDP, MDP accumulated in the mitochondria of tumor cells. Therefore, quantities of reactive oxygen species were produced via multiple enzyme-like properties including peroxidase (POD) and catalase (CAT) in a tumor microenvironment mimicking status. In additional, more energy of radiation ionizing was deposed in tumor site via Compton effect and secondary electron scattering by Ru element. Impressively, it was disclosed that the nanozyme can act as a cGAS-STING agonist to provoke immune response of the system, which hereby further elevated this combined therapy. ConclusionsCollectively, we fabricated a novel nanozyme with POD and CAT mimicking properties for the combination therapy of catalytical therapy, radiotherapy as well as immune therapy to eliminate cancer.