521 results on '"Compton scattering"'
Search Results
2. Photon-Momentum-Enabled Electronic Raman Scattering in Silicon Glass
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Kharintsev, Sergey S, Battalova, Elina I, Noskov, Aleksey I, Merham, Jovany, Potma, Eric O, and Fishman, Dmitry A
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Physical Sciences ,Condensed Matter Physics ,semiconductor glass ,electronic Raman scattering ,Compton scattering ,Urbach bridge ,photon momentum ,structural opticalspectroscopy ,structural optical spectroscopy ,Nanoscience & Nanotechnology - Abstract
The nature of enhanced photoemission in disordered and amorphous solids is an intriguing question. A point in case is light emission in porous and nanostructured silicon, a phenomenon that is still not fully understood. In this work, we study structural photoemission in heterogeneous cross-linked silicon glass, a material that represents an intermediate state between the amorphous and crystalline phases, characterized by a narrow distribution of structure sizes. This model system shows a clear dependence of photoemission on size and disorder across a broad range of energies. While phonon-assisted indirect optical transitions are insufficient to describe observable emissions, our experiments suggest these can be understood through electronic Raman scattering instead. This phenomenon, which is not commonly observed in crystalline semiconductors, is driven by structural disorder. We attribute photoemission in this disordered system to the presence of an excess electron density of states within the forbidden gap (Urbach bridge) where electrons occupy trapped states. Transitions from gap states to the conduction band are facilitated through electron-photon momentum matching, which resembles Compton scattering but is observed for visible light and driven by the enhanced momentum of a photon confined within the nanostructured domains. We interpret the light emission in structured silicon glass as resulting from electronic Raman scattering. These findings emphasize the role of photon momentum in the optical response of solids that display disorder on the nanoscale.
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- 2024
3. Coherent manipulation of giant birefringent Goos–Hänchen shifts by compton scattering using chiral atomic medium.
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Haq, Zia Ul, Ahmad, Iftikhar, Bacha, Bakht Amin, Akgül, Ali, and Hassani, Murad Khan
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COMPTON scattering , *COMPTON effect , *OPTICAL susceptibility , *CLOAKING devices , *DENSITY matrices , *CHIRALITY of nuclear particles - Abstract
A four level chiral medium is considered to analyze and investigate theoretically the reflection/transmission coefficients of right circularly polarized (RCP) beam and left circularly polarized (LCP) beam as well as their corresponding GH-shifts under the effect of compton scattering. Density matrix formalism is used for calculation of electric and magnetic probe fields coherence. The polarization and magnetization are calculated from probes coherence terms in the chiral medium. The electric and magnetic susceptibilities as well as chiral coefficients are related with polarization and magnetization. The refractive indices of RCP and LCP beams under compton scattering effect is modified from the electric/magnetic susceptibilities, chiral coefficients, mass and charge of electron as well as compton scattering angle. The giant positive and negative birefringent Goos–Hänchen (GH) shifts in reflection and transmission beams are investigated in this manuscript under Compton scattering effect. The RCP and LCP beams obey the normalization condition | R (+ , -) | + | T (+ , -) | = 1 at the interface of a lossy chiral medium of | A (+ , -) | ≃ 0 and a thin sheet of balsa wood under the effect of compton scattering angle, incident angle, probe field detuning, control field Rabi frequency, phases of electric and magnetic fields and phase of superposition states. Significant positive/negative giant GH-shifts in reflection and transmission beams are investigated. The results show potential applications in modification of cloaking devices, image coding, polarizing filters and LCD displays. [ABSTRACT FROM AUTHOR]
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- 2024
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4. The thermalization of γ-rays in radioactive expanding ejecta: a simple model and its application for Kilonovae and Ia SNe.
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Guttman, Or, Shenhar, Ben, Sarkar, Arnab, and Waxman, Eli
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TYPE I supernovae , *NUCLEAR physics , *STELLAR mergers , *COMPTON scattering , *NEUTRON stars - Abstract
A semi-analytic approximation is derived for the time-dependent fraction |$f_\gamma (t)$| of the energy deposited by radioactive decay |$\gamma$| -rays in a homologously expanding plasma of general structure. An analytic approximation is given for spherically symmetric plasma distributions. Applied to Kilonovae (KNe) associated with neutron stars mergers and Type Ia supernovae, our semi-analytic and analytic approximations reproduce, with a few per cent and 10 per cent accuracy, respectively, the energy deposition rates, |$\dot{Q}_{\rm dep}$| , obtained in numeric Monte Carlo calculations. The time |$t_\gamma$| beyond which |$\gamma$| -ray deposition is inefficient is determined by an effective frequency-independent |$\gamma$| -ray opacity |$\kappa _{\gamma ,\text{eff}}$| , |$t_\gamma = \sqrt{\kappa _{\gamma ,\text{eff}}\langle \Sigma \rangle t^2}$| , where |$\langle \Sigma \rangle \propto t^{-2}$| is the average plasma column density. For |$\beta$| -decay dominated energy release, |$\kappa _{\gamma ,\text{eff}}$| is typically close to the effective Compton scattering opacity, |$\kappa _{\gamma ,\text{eff}} \approx 0.025$| cm |$^{2}$| g |$^{-1}$| with a weak dependence on composition. For KNe, |$\kappa _{\gamma ,\text{eff}}$| depends mainly on the initial electron fraction |$Y_e$| , |$\kappa _{\gamma ,\text{eff}} \approx 0.03(0.05)$| cm |$^{2}$| g |$^{-1}$| for |$Y_e \gtrsim (\lesssim) 0.25$| (in contrast with earlier work that found |$\kappa _{\gamma ,\text{eff}}$| larger by 1–2 orders of magnitude for low |$Y_e$|), and is insensitive to the (large) nuclear physics uncertainties. Determining |$t_\gamma$| from observations will therefore measure the ejecta |$\langle \Sigma \rangle t^2$| , providing a stringent test of models. For |$\langle \Sigma \rangle t^2=2\times 10^{11}~{\rm g\, {cm}^{-2}\, s^2}$| , a typical value expected for KNe, |$t_\gamma \approx 1$| d. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Approaches, advantages, and challenges to photon counting detector and multi-energy CT.
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Toia, Giuseppe V., Mileto, Achille, Borhani, Amir A., Chen, Guang-Hong, Ren, Liqiang, Uyeda, Jennifer W., and Marin, Daniele
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PHOTON counting , *PHOTON detectors , *COMPTON scattering , *COMPUTED tomography , *SPATIAL resolution - Abstract
Photon counting detector CT (PCD-CT) is the newest major development in CT technology and has been commercially available since 2021. It offers major technological advantages over current standard-of-care energy integrating detector CT (EID-CT) including improved spatial resolution, improved iodine contrast to noise ratio, multi-energy imaging, and reduced noise. This article serves as a foundational basis to the technical approaches and concepts of PCD-CT technology with primary emphasis on detector technology in direct comparison to EID-CT. The article also addresses current technological challenges to PCD-CT with particular attention to cross talk and its causes (e.g., Compton scattering, fluorescence, charge sharing, K-escape) as well as pile-up. [ABSTRACT FROM AUTHOR]
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- 2024
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6. A compact and portable gamma-ray spectrometer (GRASP) for inertial confinement fusion and basic science experiments.
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Dannhoff, S. G., Wink, C. W., Mackie, S., Berg, G. P. A., and Frenje, J. A.
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MAGNETIC spectrometer , *MONTE Carlo method , *COMPTON scattering , *PERMANENT magnets , *SCIENTIFIC experimentation , *INERTIAL confinement fusion - Abstract
A compact and portable gamma-ray spectrometer has been designed to diagnose different components of the inertial confinement fusion-relevant γ-ray spectrum with energies between ∼3.7–17.9 MeV. The system is designed to be as compact as possible for convenient transportation and fielding in diagnostic ports on the OMEGA laser, the National Ignition Facility, and other photon-source facilities. The system consists of a conversion foil for Compton scattering in front of four magnetic spectrometer "arms," each covering a different energy range and constructed out of cylindrical permanent magnet Halbach arrays. Monte Carlo simulations have been used to optimize and assess the performance of the conversion foil, and COSY INFINITY ion-optical simulations have been used to optimize the spectrometer magnets. The performance of the design is assessed for a simulated direct-drive γ-ray spectrum. Spanning its total γ-ray energy bandwidth and using a 1.7 mm thick boron conversion foil, the system's total energy resolution and efficiency are ∼ 15.8 % –4.5% and 5.4 × 10−7–3.7 × 10−7e−/γ, respectively, with room for improvement. Spectral γ-ray measurements will provide guidance to the inertial confinement fusion program toward achieving high-energy gain relevant to inertial fusion energy and enable new measurement capabilities for basic discovery science. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Compact Compton γ-ray source from a spatiotemporal-modulated pulse scattering a high-energy electron beam.
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Yu, Q., Gu, Y. J., Zhang, Y., Kong, Q., and Kawata, S.
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COMPTON scattering , *PHOTON beams , *ELECTRON scattering , *MIRRORS , *RADIATION - Abstract
A novel plasma mirror is proposed for realizing all-optical Compton scattering, and its performance is compared with that of planar and concave plasma mirrors. Compared to a planar mirror, a concave mirror augments the radiation energy, but it decreases the collimation of the emitted photon beam. With the aid of the increased pulse length of the reflected laser, our proposed plasma mirror boosts the radiation energy and simultaneously improving the collimation of the emitted radiation. The pulse length and radius of the reflected laser can be controlled by adjusting the parameters of the proposed plasma mirror. The dependences of the pulse length and radius on the mirror parameters have been demonstrated. The impact of non-ideal conditions encountered in real experiments on the proposed mechanism has been discussed, which precisely demonstrates the robustness of the proposed mechanism. Additionally, the required gas density for a wakefield accelerator is derived to achieve optimal scattering under the given plasma mirror configurations. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Proton electromagnetic generalized polarizabilities.
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Sparveris, N. and Tomasi, Egle
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COMPTON scattering ,PROTONS ,HUMAN geography ,PARTICLES (Nuclear physics) - Abstract
Electromagnetic polarizabilities are fundamental properties of the proton that characterize its response to an external electromagnetic (EM) field. The generalization of the EM polarizabilities to non-zero four-momentum transfer opens up a powerful path to study the internal structure of the proton. They map out the spatial distribution of the polarization densities in the proton, provide access to key dynamical mechanisms that contribute to the electric and magnetic polarizability effects, and allow for the determination of fundamental characteristics of the system, such as the electric and magnetic polarizability radii. This article reviews our knowledge about proton EM generalized polarizabilities (GPs). An introduction is given to the basic concepts and the theoretical framework, which is then followed by a discussion that emphasizes the recent developments and findings of the virtual Compton scattering (VCS) experiments and future perspectives on the topic. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Fitting Compton peaks from first principles in x‐ray fluorescence spectra.
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Tee, B. P. E., Ganly, B., Mcllquham, J. D., Giang, P., and Van Haarlem, Y.
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X-ray spectra , *FLUORESCENCE spectroscopy , *COMPTON scattering , *X-ray fluorescence , *SPECTROMETRY - Abstract
A method to fit Compton profiles in x‐ray fluorescence (XRF) spectroscopy using a line shape calculated from first principles is proposed. The fitting procedure incorporates the Compton profile calculations and the double Compton scattering line shape algorithm. The results demonstrate the effectiveness of the fitting approach in accurately describing the measured scattering spectra, with good agreement observed between the fit and experimental data. The findings of this study can be used for more accurate characterization of the scattering peaks in XRF spectroscopy. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Mapping of lithium ion concentrations in 3D structures through development of in situ correlative imaging of X‐ray Compton scattering‐computed tomography.
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Leung, Chu Lun Alex, Wilson, Matthew D., Connolley, Thomas, and Huang, Chun
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X-ray imaging , *LITHIUM ions , *PHYSICAL & theoretical chemistry , *MATERIALS science , *COMPTON scattering , *MOMENTUM transfer , *IONIC conductivity - Abstract
Understanding the correlation between chemical and microstructural properties is critical for unraveling the fundamental relationship between materials chemistry and physical structures that can benefit materials science and engineering. Here, we demonstrate novel in situ correlative imaging of the X‐ray Compton scattering computed tomography (XCS‐CT) technique for studying this fundamental relationship. XCS‐CT can image light elements that do not usually exhibit strong signals using other X‐ray characterization techniques. This paper describes the XCS‐CT setup and data analysis method for calculating the valence electron momentum density and lithium‐ion concentration, and provides two examples of spatially and temporally resolved chemical properties inside batteries in 3D. XCS‐CT was applied to study two types of rechargeable lithium batteries in standard coin cell casings: (1) a lithium‐ion battery containing a cathode of bespoke microstructure and liquid electrolyte, and (2) a solid‐state battery containing a solid‐polymer electrolyte. The XCS‐CT technique is beneficial to a wide variety of materials and systems to map chemical composition changes in 3D structures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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11. Impact of scatter radiation on spectral quantification performance of first‐ and second‐generation dual‐layer spectral computed tomography.
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Salazar, Edgar, Liu, Leening P., Perkins, Amy E., Halliburton, Sandra S., Shapira, Nadav, Litt, Harold I., and Noël, Peter B.
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DUAL energy CT (Tomography) ,RADIATION exposure ,RADIATION ,COMPTON scattering - Abstract
Objective: To assess the impact of scatter radiation on quantitative performance of first and second‐generation dual‐layer spectral computed tomography (DLCT) systems. Method: A phantom with two iodine inserts (1 and 2 mg/mL) configured to intentionally introduce high scattering conditions was scanned with a first‐ and second‐generation DLCT. Collimation widths (maximum of 4 cm for first generation and 8 cm for second generation) and radiation dose levels were varied. To evaluate the performance of both systems, the mean CT numbers of virtual monoenergetic images (MonoEs) at different energies were calculated and compared to expected values. MonoEs at 50 versus 150 keV were plotted to assess material characterization of both DLCTs. Additionally, iodine concentrations were determined, plotted, and compared against expected values. For each experimental scenario, absolute errors were reported. Results: An experimental setup, including a phantom design, was successfully implemented to simulate high scatter radiation imaging conditions. Both CT scanners illustrated high spectral accuracy for small collimation widths (1 and 2 cm). With increased collimation (4 cm), the second‐generation DLCT outperformed the earlier DLCT system. Further, the spectral performance of the second‐generation DLCT at an 8 cm collimation width was comparable to a 4 cm collimation on the first‐generation DLCT. A comparison of the absolute errors between both systems at lower energy MonoEs illustrates that, for the same acquisition parameters, the second‐generation DLCT generated results with decreased errors. Similarly, the maximum error in iodine quantification was less with second‐generation DLCT (0.45 and 0.33 mg/mL for the first and second‐generation DLCT, respectively). Conclusion: The implementation of a two‐dimensional anti‐scatter grid in the second‐generation DLCT improves the spectral quantification performance. In the clinical routine, this improvement may enable additional clinical benefits, for example, in lung imaging. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Compton Imaging Systems Based on CdZnTe/CdTe Detectors
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Niknami, Mostafa, Hosseini, Seyed Abolfazl, Valipour, Mahdi, and Iniewski, Kris, editor
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- 2024
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13. A Novel Algorithm to Create Quantitative X-Ray Images Based on Precise Analysis of Polychromatic X-Ray Attenuation
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Kimoto, Natsumi, Hayashi, Hiroaki, Nishigami, Rina, Kobayashi, Daiki, Maeda, Tatsuya, Katsumata, Akitoshi, Iniewski, Kris, editor, and Gadey, Harish, editor
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- 2024
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14. Radiation Interactions with Matter
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Ranjbar, Lily, Iniewski, Kris, editor, and Gadey, Harish, editor
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- 2024
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15. Interaction of Ionizing Radiation with Matter
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Palani Selvam, T., Shrivastava, Vandana, Chinnaesakki, S., and Aswal, Dinesh Kumar, editor
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- 2024
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16. Time Projection Chambers for Gamma-Ray Astronomy
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Bernard, Denis, Hunter, Stanley D., Tanimori, Toru, Bambi, Cosimo, editor, and Santangelo, Andrea, editor
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- 2024
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17. Compton Telescopes for Gamma-Ray Astrophysics
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Kierans, Carolyn, Takahashi, Tadayuki, Kanbach, Gottfried, Bambi, Cosimo, editor, and Santangelo, Andrea, editor
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- 2024
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18. Compton Polarimetry
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Del Monte, Ettore, Fabiani, Sergio, Pearce, Mark, Bambi, Cosimo, editor, and Santangelo, Andrea, editor
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- 2024
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19. Soft Gamma-Ray Polarimetry with COSI Using Maximum Likelihood Analysis
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Tomsick, John A., Lowell, Alexander, Lazar, Hadar, Sleator, Clio, Zoglauer, Andreas, Bambi, Cosimo, editor, and Santangelo, Andrea, editor
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- 2024
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20. Scattered Ray Correction for High-Energy X-Ray Nondestructive Testing System for Nuclear Fuel Assemblies Based on MC Method
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Zhi ZHONG, Gaokui HE, and Xiangyang ZHANG
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nuclear fuel assembly ,high energy x-ray nondestructive testing ,compton scattering ,monte carlo method ,geant4 ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
High energy X-ray non-destructive testing technology can obtain the internal structure information of the inspected object without destroying it. The multi-rod-beam nature of nuclear fuel assemblies can lead to severe scattering ray effects,which can degrade image quality. In order to correct the interference of scattering ray,this study analyzed the limitations of various methods to solve the interference of scattered rays in the non-destructive testing of nuclear fuel assemblies. Geant4 is used to simulate the nondestructive testing process of nuclear fuel components,and ComptonFlag class is constructed to mark the scattered rays of Compton scattering and remove their interference. The simulation results show that the CNR of defective and intact components in the projection image is increased by 69.02% after the scattering ray interference is removed,which can effectively improve the image quality of non-destructive testing of nuclear fuel assemblies.
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- 2024
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21. Dynamics, quantum states and Compton scattering in nonlinear gravitational waves.
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Audagnotto, G. and Di Piazza, A.
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COMPTON scattering , *QUANTUM states , *NONLINEAR waves , *PARTICLE dynamics , *PLANE wavefronts - Abstract
The classical dynamics and the construction of quantum states in a plane wave curved spacetime are examined, paying particular attention to the similarities with the case of an electromagnetic plane wave in flat spacetime. A natural map connecting the dynamics of a particle in the Rosen metric and the motion of a charged particle in an electromagnetic plane wave is unveiled. We then discuss how this map can be translated into the quantum description by exploiting the large number of underlying symmetries. We examine the complete analogy between Volkov solutions and fermion states in the Rosen chart and properly extend this to massive vector bosons. We finally report the squared S-matrix element of Compton scattering in a sandwich plane wave spacetime in the form of a two-dimensional integral. [ABSTRACT FROM AUTHOR]
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- 2024
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22. Determining effects of doping lithium nickel oxide with tungsten using Compton scattering.
- Author
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Kothalawala, Veenavee Nipunika, Suzuki, Kosuke, Li, Xin, Barbiellini, Bernardo, Nokelainen, Johannes, Makkonen, Ilja, Ferragut, Rafael, Tynjälä, Pekka, Laine, Petteri, Välikangas, Juho, Hu, Tao, Lassi, Ulla, Takano, Kodai, Tsuji, Naruki, Amada, Yosuke, Sasikala Devi, Assa Aravindh, Alatalo, Matti, Sakurai, Yoshiharu, Sakurai, Hiroshi, and Babar, Mohammad
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NICKEL oxides ,TUNGSTEN ,COMPTON scattering ,LITHIUM-ion batteries ,ELECTRIC conductivity - Abstract
X-ray Compton scattering experiments along with parallel first-principles computations were carried out on LiNiO
2 to understand the effects of W doping on this cathode material for Li-ion batteries. By employing high-energy x rays exceeding 100 keV, an insight is gained into the fate of the W valence electrons, which are adduced to undergo transfer to empty O 2p energy bands within the active oxide matrix of the cathode. The substitution of W for Ni is shown to increase the electronic conductivity and to enhance the total magnetization per Ni atom. Our study demonstrates that an analysis of line shapes of Compton scattered x rays in combination with theoretical modeling can provide a precise method for an atomic level understanding of the nature of the doping process. [ABSTRACT FROM AUTHOR]- Published
- 2024
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23. Extracting the electronic structure of light elements in bulk materials through a Compton scattering method in the readily accessible hard x-ray regime.
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Kothalawala, Veenavee Nipunika, Guruswamy, Tejas, Quaranta, Orlando, Patel, Umeshkumar Manibhai, Gades, Lisa, Taddei, Keith, Yakovenko, Andrey, Zheng, Meiying, Morgan, Kelsey, Weber, Joel, Yan, Daikang, Swetz, Daniel, Makkonen, Ilja, Yeddu, Hemantha Kumar, Bansil, Arun, Ruett, Uta, Miceli, Antonino, Nokelainen, Johannes, and Barbiellini, Bernardo
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HARD X-rays , *COMPTON scattering , *ELECTRONIC structure , *LIGHT elements , *ELECTRON gas , *X-ray absorption near edge structure , *FREE electron lasers - Abstract
Our Compton profile measurements of Ti and TiH2 using readily available hard X-ray radiation at 27.5 keV, detected by both a Hitachi Vortex silicon-drift detector and a high-resolution superconducting transition-edge sensor array, are found to be in excellent accord with state-of-the-art density functional theory based calculations. The spherically averaged difference between the Compton profiles of TiH2 and Ti is well described by an inverted parabola, supporting an itinerant behavior of the electron gas screening the protons in the Ti matrix. Our experimental approach, validated by two different detectors, extends the applicability of Compton scattering technique to the readily accessible hard x-ray regime (below 30 keV). Our study suggests possibilities for experiments at low-flux bending magnet synchrotron beamlines and paves the way for the development of tabletop Compton experiments with x-ray tubes. [ABSTRACT FROM AUTHOR]
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- 2024
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24. Non-thermal emission in M31 and M33.
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Persic, Massimo, Rephaeli, Yoel, and Rando, Riccardo
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SPECTRAL energy distribution , *SPIRAL galaxies , *THERMAL electrons , *COMPTON scattering , *PULSARS , *MAGELLANIC clouds , *SEYFERT galaxies , *HADRONIC atoms - Abstract
Context. Spiral galaxies M31 and M33 are among the γ-ray sources detected by the Fermi Large Area Telescope (LAT). Aims. We aim to model the broadband non-thermal emission of the central region of M31 (a LAT point source) and of the disk of M33 (a LAT extended source), as part of our continued survey of non-thermal properties of local galaxies that includes the Magellanic Clouds. Methods. We analysed the observed emission from the central region of M31 (R < 5.5 kpc) and the disk-sized emission from M33 (R ∼ 9 kpc). For each galaxy, we self-consistently modelled the broadband spectral energy distribution of the diffuse non-thermal emission based on published radio and γ-ray data. All relevant radiative processes involving relativistic and thermal electrons (synchrotron, Compton scattering, bremsstrahlung, and free–free emission and absorption), along with relativistic protons (π0 decay following interaction with thermal protons), were considered, using exact emissivity formulae. We also used the Fermi-LAT-validated γ-ray emissivities for pulsars. Results. Joint spectral analyses of the emission from the central region of M31 and the extended disk of M33 indicate that the radio emission is composed of both primary and secondary electron synchrotron and thermal bremsstrahlung, whereas the γ-ray emission may be explained as a combination of diffuse pionic, pulsar, and nuclear-BH-related emissions in M31 and plain diffuse pionic emission (with an average proton energy density of 0.5 eV cm−3) in M33. Conclusions. The observed γ-ray emission from M33 appears to be mainly hadronic. This situation is similar to other local galaxies, namely, the Magellanic Clouds. In contrast, we have found suggestions of a more complex situation in the central region of M31, whose emission could be an admixture of pulsar emission and hadronic emission, with the latter possibly originating from both the disk and the vicinity of the nuclear black hole. The alternative modelling of the spectra of M31 and M33 is motivated by the different hydrogen distribution in the two galaxies: The hydrogen deficiency in the central region of M31 partially unveils emissions from the nuclear BH and the pulsar population in the bulge and inner disk. If this were to be the case in M33 as well, these emissions would be outshined by diffuse pionic emission originating within the flat central-peak gas distribution in M33. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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25. N‐representable one‐electron reduced density matrix reconstruction with frozen core electrons.
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Yu, Sizhuo and Gillet, Jean-Michel
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DENSITY matrices , *SEMIDEFINITE programming , *DATA corruption , *ELECTRON density , *ELECTRONS , *COMPTON scattering - Abstract
Recent advances in quantum crystallography have shown that, beyond conventional charge density refinement, a one‐electron reduced density matrix (1‐RDM) satisfying N‐representability conditions can be reconstructed using jointly experimental X‐ray structure factors and directional Compton profiles (DCP) through semidefinite programming. So far, such reconstruction methods for 1‐RDM, not constrained to idempotency, have been tested only on a toy model system (CO2). In this work, a new method is assessed on crystalline urea [CO(NH2)2] using static (0 K) and dynamic (50 K) artificial experimental data. An improved model, including symmetry constraints and frozen core‐electron contribution, is introduced to better handle the increasing system complexity. Reconstructed 1‐RDMs, deformation densities and DCP anisotropy are analysed, and it is demonstrated that the changes in the model significantly improve the reconstruction quality, even when there is insufficient information and data corruption. The robustness of the model and the strategy are thus shown to be well adapted to address the reconstruction problem from actual experimental scattering data. [ABSTRACT FROM AUTHOR]
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- 2024
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26. Fluid and kinetic studies of tokamak disruptions using Bayesian optimization.
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Ekmark, I., Hoppe, M., Fülöp, T., Jansson, P., Antonsson, L., Vallhagen, O., and Pusztai, I.
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COST functions , *BETA decay , *COMPTON scattering , *ELECTRON transport , *HEAT losses , *TRITIUM , *DEUTERIUM - Abstract
When simulating runaway electron dynamics in tokamak disruptions, fluid models with lower numerical cost are often preferred to more accurate kinetic models. The aim of this work is to compare fluid and kinetic simulations of a large variety of different disruption scenarios in ITER. We consider both non-activated and activated scenarios; for the latter, we derive and implement kinetic sources for the Compton scattering and tritium beta decay runaway electron generation mechanisms in our simulation tool Dream (Hoppe et al. , Comput. Phys. Commun. , vol. 268, 2021, 108098). To achieve a diverse set of disruption scenarios, Bayesian optimization is used to explore a range of massive material injection densities for deuterium and neon. The cost function is designed to distinguish between successful and unsuccessful disruption mitigation based on the runaway current, current quench time and transported fraction of the heat loss. In the non-activated scenarios, we find that fluid and kinetic disruption simulations can have significantly different runaway electron dynamics, due to an overestimation of the runaway seed by the fluid model. The primary cause of this is that the fluid hot-tail generation model neglects superthermal electron transport losses during the thermal quench. In the activated scenarios, the fluid and kinetic models give similar predictions, which can be explained by the significant influence of the activated sources on the runaway dynamics and the seed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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27. Manipulation of γ-ray polarization in Compton scattering.
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Wang, Yu, Ababekri, Mamutjan, Wan, Feng, Wen, Jia-Xing, Wei, Wen-Qing, Li, Zhong-Peng, Kang, Hai-Tao, Zhang, Bo, Zhao, Yong-Tao, Zhou, Wei-Min, and Li, Jian-Xing
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COMPTON scattering , *NUCLEAR physics , *ANGULAR momentum (Mechanics) , *POLARIZED photons , *MULTIPHOTON absorption , *ELECTRON beams - Abstract
High-brilliance high-polarization γ rays based on Compton scattering are of great significance in broad areas, such as nuclear physics, high-energy physics, astrophysics, etc. However, the transfer mechanism of spin angular momentum in the transition from linear through weakly into strongly nonlinear processes is still unclear, which severely limits the simultaneous control of brilliance and polarization of high-energy γ rays. In this work, we clarify the transfer mechanism in the transition regions and put forward a clear way to efficiently manipulate the polarization of emitted photons. We find that to simultaneously generate high-energy, high-brilliance, and high-polarization γ rays, it is better to increase the laser intensity for the initially spin-polarized electron beam. However, for the case of employing the initially spin-nonpolarized electron beam, in addition to increasing laser intensity, it is also necessary to increase the energy of the electron beam. Because the γ photon polarization emitted through the single-photon absorption channel is mainly attributed to the spin transfer of laser photons, while in multi-photon absorption channels, the electron spin plays a major role. Moreover, we confirm that the signature of γ-ray polarization can be applied to observing the nonlinear effects (multi-photon absorption) of Compton scattering with moderate-intensity laser facilities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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28. The Momentous Discovery of Neutron.
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Desai, Pruthul and Mody, Ashok
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SCIENTIFIC literacy ,NUCLEAR structure ,COMPTON scattering ,NEUTRONS ,SCIENTIFIC discoveries - Abstract
The discovery of neutron ushered in a paradigm shift in our understanding of the subatomic world. The electrically neutral neutron does not experience Coulomb repulsion produced by the positively charged protons inside the nucleus. As a result, a neutron can penetrate deep into the nucleus and thus is a powerful probe to unravel the nuclear structure. In 1920, Rutherford prophetically predicted the existence of an electrically neutral particle inside the nucleus. It took more than a decade of painstaking experimentation to finally discover it in 1932. The historical aspects of a scientific discovery, for one reason or another, often, do not find their place in the normal discourse at both school and college levels. Studying the historical development of an idea can inspire, excite curiosity among, and familiarize students about how science works. In this article, we have tried to show how the relevant historical information can be integrated in traditional instructions while discussing the discovery of neutron which may enhance the curriculum outcomes and increase scientific literacy. We have discussed two important experiments that hinted at the existence of a new particle inside the nucleus. The arguments that led Chadwick to the ultimate discovery of neutron are also presented. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Fully polarized Compton scattering in plane waves and its polarization transfer.
- Author
-
Tang, Suo, Xin, Yu, Wen, Meng, Bake, Mamat Ali, and Xie, Baisong
- Subjects
PLANE wavefronts ,PHOTON scattering ,ELECTRON spin ,COMPTON scattering ,ELECTRON beams ,PHOTONS ,LASERS - Abstract
Fully polarized Compton scattering from a beam of spin-polarized electrons is investigated in plane-wave backgrounds in a broad intensity region from the perturbative to the nonperturbative regimes. In the perturbative regime, polarized linear Compton scattering is considered for investigating polarization transfer from a single laser photon to a scattered photon, and in the high-intensity region, the polarized locally monochromatic approximation and locally constant field approximation are established and are employed to study polarization transfer from an incoming electron to a scattered photon. The numerical results suggest an appreciable improvement of about 10% in the scattering probability in the intermediate-intensity region if the electron's longitudinal spin is parallel to the laser rotation. The longitudinal spin of the incoming electron can be transferred to the scattered photon with an efficiency that increases with laser intensity and collisional energy. For collision between an optical laser with frequency ∼1 eV and a 10 GeV electron, this polarization transfer efficiency can increase from about 20% in the perturbative regime to about 50% in the nonperturbative regime for scattered photons with relatively high energy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Quantum error channels in high energetic photonic systems.
- Author
-
Hiesmayr, B. C., Krzemień, W., and Bała, M.
- Subjects
- *
POSITRON emission tomography , *QUANTUM computing , *COMPTON scattering - Abstract
In medical applications—such as positron emission tomography (PET)—511 keV photons that experience Compton scattering are studied. We present a consistent framework based on quantum error-correction channels—intensively studied in quantum computing—to fully describe the quantum information-theoretic content of high energetic photons undergoing Compton scattering, characterized by the Klein–Nishina formula in unoriented matter. In this way, we can predict the expected spatial distribution of two or more, pure or mixed, polarization entangled or separable photons. This framework allows us to characterize the accessible and inaccessible information for different parameter ranges. It also answers the question of how to describe successive multi-photon scattering. In addition our formalism provides a complete framework for dealing with single and all multi-partite errors that can occur in the propagation, providing the basis for modeling future dedicated experiments that will then have applications in medicine, such as reducing errors in PET imaging or exploring possibilities for quantum-based diagnostic indicators. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Compton Scattering of Two Photons by an Atomic Ion.
- Author
-
Hopersky, A. N., Nadolinsky, A. M., and Koneev, R. V.
- Subjects
- *
ION scattering , *DIFFERENTIAL cross sections , *COMPTON scattering , *SCATTERING amplitude (Physics) , *IONS - Abstract
The analytical structure and absolute values of the doubly differential cross section of the Compton scattering of two X-ray photons by a multicharged neon-like atomic ion are theoretically predicted. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Spectral information content of Compton scattering events in silicon photon counting detectors.
- Author
-
Hsieh, Scott S. and Taguchi, Katsuyuki
- Subjects
- *
PHOTON detectors , *COMPTON effect , *THRESHOLD energy , *PHOTOELECTRIC effect , *SILICON , *WATER filters , *COMPTON scattering , *PHOTON counting - Abstract
Background: Silicon (Si) is a possible sensor material for photon counting detectors (PCDs). A major drawback of Si is that roughly two‐thirds of x‐ray interactions in the diagnostic energy range are Compton scattering. Because Compton scattering is an energy‐insensitive process, it is commonly assumed that Compton events retain little spectral information. Purpose: To quantify how much information can be recovered from Compton scattering events in models of Si PCDs. Methods: We built a simplified model of Si interactions including two interaction mechanisms: photoelectric effect and Compton scattering. We considered three different binning options that represent strategies for handling Compton events: in Compton censoring, all events under 38 keV (the maximum energy possible from Compton scattering for a 120 keV incident photon) were discarded; in Compton counting, all events between 1 and 38 keV were placed into a single bin; in Compton binning, all events were placed into energy bins of uniform width. These were compared to the ideal detector, which always recorded the correct energy (i.e., 100% photoelectric effect). Every photon was assumed to interact once and only once with Si, and the energy bin width was 5 keV. In the primary analysis, the Si detector was irradiated with a 120 kV spectrum filtered by 30 cm of water, with 99.5% of the arriving spectrum above 38 keV so that there was good separation between photoelectric effect and Compton scattering, and the figures of merit were the Cramér–Rao lower bound (CRLB) of the variance of iodine and water basis material decomposition images, as well as the CRLB of virtual monoenergetic images (i.e., linear combinations of material images) that maximize iodine CNR or water CNR. We also constructed a local linear estimator that attains the CRLB. In secondary analyses, we applied other sources of spectral distortion: (1) a nonzero minimum energy threshold; (2) coarser, 10 keV energy bins; and (3) a model of charge sharing. Results: With our chosen spectrum, 67% of the interactions were Compton scattering. Consistent with this, the material decomposition variance for the Compton censoring model, averaged over both basis materials, was 258% greater than the ideal detector. If Compton events carried no spectral information, the Compton counting model would show similar variance. Instead, its basis material variance was 103% greater than the ideal detector, implying that Compton counts indeed carry significant spectral information. The Compton binning model had a basis material variance 60% greater than the ideal detector. The Compton binning model was not affected by a 5 keV minimum energy threshold, but the variance increased from 60% to 107% when charge sharing was included and to 78% with coarser energy bins. For optimized CNR images, the average variance was 149%, 12%, and 10% higher than the ideal detector for the Compton censoring, counting, and binning models, reinforcing the hypothesis that Compton counts are useful for detection tasks and that precise energy assignments are not necessary. Conclusions: Substantial spectral information remains after Compton scattering events in silicon PCDs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Scintillation characteristics of the EJ-299-02H scintillator.
- Author
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Floyd, N., Hassan, Md. T., Tang, Z., Krivoš, M., Blatnik, M., Cude-Woods, C., Clayton, S. M., Holley, A. T., Ito, T. M., Johnson, B. A., Liu, C.-Y., Makela, M., Morris, C. L., Navazo, A. S. C., O'Shaughnessy, C. M., Renner, E. L., Pattie, R. W., and Young, A. R.
- Subjects
- *
SCINTILLATORS , *ULTRACOLD neutrons , *BETA rays , *COMPTON scattering , *ELECTRON scattering , *THRESHOLD energy - Abstract
A study of the dead layer thickness and quenching factor of a plastic scintillator for use in ultracold neutron (UCN) experiments is described. Alpha spectroscopy was used to determine the thickness of a thin surface dead layer to be 630 ± 110 nm. The relative light outputs from the decay of 241Am and Compton scattering of electrons were used to extract Birks' law coefficient, yielding a kB value of 0.087 ± 0.003 mm/MeV, consistent with some previous reports for other polystyrene-based scintillators. The results from these measurements are incorporated into the simulation to show that an energy threshold of (∼9 keV) can be achieved for the UCNProBe experiment. This low threshold enables high beta particle detection efficiency and the indirect measurement of UCN. The ability to make the scintillator deuterated, accompanied by its relatively thin dead layer, gives rise to unique applications in a wide range of UCN experiments, where it can be used to trap UCN and detect charged particles in situ. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Scintillation Detectors of Compton Polarimeters for Measuring Polarization States of Annihilation Photons.
- Author
-
Baranov, A. G., Ivashkin, A. P., Musin, S. A., Salakhutdinov, G. H., and Strizhak, A. O.
- Subjects
- *
SCINTILLATION counters , *PHOTON detectors , *PHOTONS , *GAMMA ray sources , *QUANTUM states , *COMPTON scattering , *POLARISCOPE , *POSITRONIUM - Abstract
The design and parameters of scintillation detectors of Compton polarimeters for measuring photons formed during the annihilation of electron-positron pairs at rest are considered. The discussed setup makes it possible to measure and compare the polarization correlations of scattered annihilation photons in these two quantum states. The amplitude parameters of scatterers and scattered photon detectors obtained from preliminary tests of these detectors using radioactive gamma sources, as well as in the process of collecting experimental data, are given. The possibility of measuring and comparing the polarization correlations of scattered annihilation photons is shown. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
35. Model of a "Warm Corona" as the origin of the soft X-ray excess of active galactic nuclei.
- Author
-
Kawanaka, Norita and Mineshige, Shin
- Subjects
- *
ACTIVE galactic nuclei , *SOFT X rays , *BINARY black holes , *COMPTON scattering , *ACCRETION (Astrophysics) , *ACCRETION disks - Abstract
The soft X-ray excess in the spectra of active galactic nuclei is characterized by similar electron temperatures of 0.1–0.3 keV and similar photon indices around 2.2–3, if fitted with inverse Comptonization. It remains a puzzle why both values are not sensitive to the black hole mass nor the accretion rate. Supposing that the scattering-dominated surface layer of an accretion disk can act as a warm corona, we construct a vertical one-zone model to understand what determines its temperature. By solving the equations of (1) the condition for the effective optical depth, (2) the energy balance, and (3) the dominance of the Compton cooling over the bound–free cooling, we could reproduce the basic observational features of the soft excess, provided that anomalous heating (excess heating other than what is expected by local energy dissipation) takes place in the warm corona in agreement with similar studies done so far. The similar temperatures can be understood, since both the anomalous heating and Compton cooling rates are proportional to the dissipation rate of the accretion energy, while similar photon indices are a natural consequence of the fact that observed photons are finally emitted from the layer of Compton y ∼ 1. The soft excess is not observed in black hole binaries, since disk temperatures are too high for the Compton scattering to work as cooling. The derived temperatures are somewhat of an underestimation, however. This may indicate a necessity of multi-zone corona structure. The stability of the warm corona and its consequences are briefly discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Prompt Photon Production in Sub-Processes and of Compton Scattering in Proton–Proton Collision at NICA Energies.
- Author
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Alizada, M. R., Ahmadov, A. I., and Arbuzov, A. B.
- Abstract
Dependence of the differential cross section of the production of prompt photons with sub-processes of mixed chromo-electrodynamic and pure electrodynamic Compton scattering on the total energy of colliding protons , the transverse momentum p
T of photons, the cosine of the scattering angle cos(θ), and the rapidity of photons y is studied. It has been shown that the purely electrodynamic sub-process can contribute up to the order of ten percent of the total cross-section of the production of prompt photons at NICA energies and, consequently, should be taken into account in simulating and analyzing experimental data. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
37. Temperature measurements with the relativistic Sunyaev-Zel'dovich effect.
- Author
-
Perrott, Y.
- Subjects
- *
SUNYAEV-Zel'dovich effect , *TEMPERATURE measurements , *RELATIVISTIC astrophysics , *TELESCOPES , *COMPTON scattering - Abstract
At temperatures above ∼5 keV, the non-relativistic approximation used to derive the classical thermal Sunyaev-Zel'dovich effect spectrum begins to fail. When relativistic effects are included, the spectrum becomes temperature-dependent. This leads to both a problem and an opportunity: a problem, because when the temperature dependence is not accounted for the Compton-y estimate is biased; and an opportunity, because it represents a new way to measure the temperature of the intracluster medium independently of X-ray observations. This work presents current results from investigating the impact of relativistic effects on Planck cluster observations, and projections for future measurements of cluster temperatures using the Atacama Large Aperture Sub-millimetre Telescope. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. 3D scaling laws and projection effects in The300-NIKA2 Sunyaev-Zeldovich Large Program Twin Samples.
- Author
-
Paliwal, A., Cui, W., de Andrés, D., De Petris, M., Ferragamo, A., Hanser, C., Macías-Pérez, J.-F., Mayet, F., Moyer-Anin, A., Muñoz-Echeverría, M., Perotto, L., Rasia, E., and Yepes, G.
- Subjects
- *
SUNYAEV-Zel'dovich effect , *SCALING laws (Statistical physics) , *GALAXY clusters , *STELLAR mass , *COMPTON scattering - Abstract
The abundance of galaxy clusters with mass and redshift is a wellknown cosmological probe. The cluster mass is a key parameter for studies that aim to constrain cosmological parameters using galaxy clusters, making it critical to understand and properly account for the errors in its estimates. Subsequently, it becomes important to correctly calibrate scaling relations between observables like the integrated Compton parameter and the mass of the cluster. The NIKA2 Sunyaev-Zeldovich Large program (LPSZ) enables one to map the intracluster medium profiles in the mm–wavelength band with great details (resolution of 11 & 17″ at 1.2 & 2 mm, respectively) and hence, to estimate the cluster hydrostatic mass more precisely than previous SZ observations. However, there are certain systematic effects which can only be accounted for with the use of simulations. For this purpose, we employ The Three Hundred simulations which have been modelled with a range of physics modules to simulate galaxy clusters. The so-called twin samples are constructed by picking synthetic clusters of galaxies with properties close to the observational targets of the LPSZ. In particular, we use the Compton parameter maps and projected total mass maps of these twin samples along 29 different lines of sight. We investigate the scatter that projection induces on the total masses. Eventually, we consider the statistical values along different lines of sight to construct a kind of 3D scaling law between the integrated Compton parameter, total mass, and overdensity of the galaxy clusters to determine the overdensity that is least impacted by the projection effect. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Systematic effects on the upcoming NIKA2 LPSZ scaling relation.
- Author
-
Moyer-Anin, A., Adam, R., Ade, P., Ajeddig, H., André, P., Artis, E., Aussel, H., Bartalucci, I., Beelen, A., Benoît, A., Berta, S., Bing, L., Bourrion, O., Calvo, M., Catalano, A., De Petris, M., Désert, F.-X., Doyle, S., Driessen, E.F.C., and Ejlali, G.
- Subjects
- *
GALAXY clusters , *STELLAR mass , *COMPTON scattering , *REDSHIFT , *X-rays - Abstract
In cluster cosmology, cluster masses are the main parameter of interest. They are needed to constrain cosmological parameters through the cluster number count. As the mass is not an observable, a scaling relation is needed to link cluster masses to the integrated Compton parameters Y, i.e. the Sunyaev-Zeldovich observable (SZ). Planck cosmological results obtained with cluster number counts are based on a scaling relation measured with clusters at low redshift (z<0.5) observed in SZ and X-ray. In the SZ Large Program (LPSZ) of the NIKA2 collaboration, the scaling relation will be obtained with a sample of 38 clusters at intermediate to high redshift (0.5 < z < 0.9) and observed at high angular resolution in both SZ and X-ray. Thanks to analytical simulation of LPSZ-like samples, we take into account the LPSZ selection function and correct for its effects. Besides, we show that white and correlated noises in the SZ maps do not affect the scaling relation estimation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Galaxy clusters morphology with Zernike polynomials: The first application on Planck Compton parameter maps.
- Author
-
Capalbo, V., De Petris, M., Cui, W., Ferragamo, A., Ruppin, F., and Yepes, G.
- Subjects
- *
GALAXY clusters , *ZERNIKE polynomials , *COMPTON scattering , *PLANCK (Artificial satellite) , *HYDRODYNAMICS - Abstract
The study of the morphology of 2D projected maps of galaxy clusters is a suitable approach to infer, from real data, the dynamical state of those systems. We recently developed a new method to recover the morphological features in galaxy cluster maps which consists of an analytical modelling through the Zernike polynomials. The validation of this approach was done on a set of high-resolution mock maps of the Compton parameter y. These maps are from hydrodynamically simulated galaxy clusters in The Three Hundred project. After this step, we apply the Zernike modelling on y-maps of local (z < 0.1) galaxy clusters observed by the Planck satellite. With a single parameter collecting the main information of the Zernike modelling, we classify their morphology. A set of mock Planck-like y-maps, generated from The Three Hundred clusters, is also used to validate our indicator with a proper dynamical state classification. This approach allows us to test the efficiency of the Zernike morphological modelling in evaluating the dynamical population in the real Planck sample. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Towards measurements of CMB spectral distortions.
- Author
-
Coulon, Xavier, Maffei, Bruno, and Aghanim, Nabila
- Subjects
- *
COSMIC background radiation , *OPTICAL distortion , *SPECTRAL energy distribution , *COMPTON scattering , *SPECTRUM analysis - Abstract
High-precision spectroscopy of the Cosmic Microwave Background (CMB) is one of the three themes that have been selected by the ESA Voyage 2050 programme. Several space missions dedicated to the measurement of the CMB spectral distortions such as PIXIE, PRISTINE, and FOSSIL have been proposed since 2011. Additionally, balloon-borne projects, such as BISOU, have also been considered as a pathfinder for a future space mission. This paper presents an effort undertaken to define future missions and instruments dedicated to the measurement of the CMB spectral distortions. For this purpose, models allowing to optimize both instrument concept and mission parameters (mission duration, scanning strategy, ...) have been developed. It has been applied to two specific cases, FOSSIL, a space mission proposed to answer the ESA M7 call in 2022 , and BISOU, a CNES Phase 0 study for a balloon-borne mission. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. An updated and improved thermal SZ y-map from Planck PR4 data.
- Author
-
Chandran, Jyothis, Remazeilles, Mathieu, and Barreiro, R.B.
- Subjects
- *
SUNYAEV-Zel'dovich effect , *COMPTON scattering , *NOISE control , *SENSITIVITY analysis , *ASTRONOMICAL observations - Abstract
In 2015, the Planck Collaboration released an all-sky map of the thermal Sunyaev-Zeldovich (SZ) effect, obtained by implementing the needlet internal linear combination (NILC) method on the Planck PR2 data. The quality of the Planck data has significantly improved since then. The Planck PR4 data release offers upgraded full-sky maps in the LFI and HFI frequency bands with improved systematics and sensitivity. We present a new all-sky thermal SZ Compton y-parameter map derived from the Planck PR4 data using NILC and highlight improvements, particularly in noise reduction and handling residual foreground contamination. The PR4 NILC Compton y-parameter map has been made publicly available to support further analyses. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Correction to the quantum relation of photons in the Doppler effect based on a special Lorentz violation model
- Author
-
Jinwen Hu and Huan Hu
- Subjects
Lorentz model ,The speed of light ,Lorentz violation model ,Doppler effect ,Compton scattering ,Inverse Compton scattering ,Physics ,QC1-999 - Abstract
The possibility of the breaking of Lorentz symmetry has been discussed in many models of quantum gravity. In this paper we follow the Lorentz violation model in Ref. [14] (i.e., our previous work) to discuss the Doppler frequency shift of photons and the Compton scattering process between photons and electrons, pointing out that following the idea in Ref. [14] we have to modify the usual quantum relation of photons in the Doppler effect. But due to the current limited information and knowledge, we could not yet determine the specific expression for the correction coefficient in the modified quantum relation of photons. However, the phenomenon called spontaneous radiation in a cyclotron maser give us an opportunity to see what the expression for this correction coefficient might look like. Therefor, under some necessary constraints, we construct a very concise expression for this correction coefficient through the discussion of different cases. And then we use this expression to analyze the wavelength of radiation in the cyclotron maser, which tends to a limited value at v → c, rather than to 0 as predicted by the Lorentz model. And the inverse Compton scattering phenomenon is also discussed and we find that there is a limit to the maximum energy that can be obtained by photons in the collision between extremely relativistic particles and low-energy photons, which conclusion is also very different from that obtained from the Lorentz model, in which the energy that can be obtained by the photon tends to be infinite as the velocity of particle is close to c. This paper still follows the purpose in Ref. [14] that the energy and momentum of particles (i.e., any particles, including photons) cannot be infinite, otherwise it will make some physical scenarios invalid. When the parameter Q characterizing the degree of deviation from the Lorentz model is equal to 0, all the results and conclusions in this paper will return to the case as in the Lorentz model, so this paper also provides us with a possible experimental scheme to determine the value of Q in Ref. [14], although it still requires extremely high experimental energy.
- Published
- 2024
- Full Text
- View/download PDF
44. Strategies for mitigating inter-crystal scattering effects in positron emission tomography: a comprehensive review
- Author
-
Lee, Min Sun, Shim, Hyeong Seok, and Lee, Jae Sung
- Published
- 2024
- Full Text
- View/download PDF
45. Investigation of radiation shielding parameters of boron compounds.
- Author
-
Levet, Aytaç
- Subjects
- *
RADIATION shielding , *BORON compounds , *TITANIUM hydride , *BORON carbides , *ELECTRON density , *COMPTON scattering - Abstract
The radiation shielding parameters such as effective atomic number, effective electron density, mean free path (MFP), half value layer (HVL) and tenth value layer (TVL) were calculated experimentally and theoretically for Boron Carbide(BC4), Boron nitride (BN), Boric acid (H3BO3), Iron boride (Fe2B), Lanthanum borate (BLaO3), Sodium borohydride (NaBH4), Borax (Na2H20B4O17), Titanium diboride (TiB2), and Zirconium diboride (ZrB2) compounds. In experimental measurements, the compounds were irradiated by 137Ba, 152Eu and 241Am radioactive gamma-ray sources. The theoretical results obtained with the help of the WinXCom computer program were compared with the experimental results and they were found to be in good agreement. Moreover, energy absorption buildup factor (EABF) and exposure buildup factor (EBF) values were calculated for compounds using the geometric progression (G.P.) fitting formula for the energy range of 0.015–15 MeV and penetration depth up to 40 mfp (mean free path). Buildup factors (EABF, EBF) increased with increasing penetration depth. In general, the buildup factors for all compounds formed a Gaussian curve and had the highest values in the energy range dominated by Compton scattering. As a result of the findings obtained in the study, it was seen that Lanthanum borate gave the best results in radiation shielding. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Increase in the Brightness of the Cosmic Radio Background toward Galaxy Clusters.
- Author
-
Grebenev, S. A. and Sunyaev, R. A.
- Subjects
- *
COSMIC background radiation , *BREMSSTRAHLUNG , *SYNCHROTRON radiation , *MICROWAVE scattering , *COMPTON scattering , *HEAT radiation & absorption , *ELECTRON scattering , *GALAXY clusters - Abstract
We explore the possibility of detecting the excess of the cosmic radio background toward galaxy clusters due to its Compton scattering by electrons of the hot intergalactic gas. When mapping the background fluctuations at frequencies below MHz, this effect gives rise to a radio source at the location of the cluster. At higher frequencies, where the microwave (relic) radiation dominates in the cosmic background, a "negative" source (a "shadow" on the map of background fluctuations) is observed at the location of the cluster due to the transfer of some of the relic photons upward along the frequency axis upon their scattering (into the range GHz; Sunyaev and Zeldovich 1970, 1972). We have computed the spectra of the expected radio background distortions for various parameters of clusters and show that in many cases in the wide frequency range the measurement of the distortions will be hindered by the intrinsic thermal (bremsstrahlung) radiation from the intergalactic gas and the scattered radio emission from cluster galaxies associated with their past activity, including the synchrotron radiation from ejected relativistic electrons. Below MHz the scattering effect always dominates over the thermal gas radiation due to the general increase in the intensity of the cosmic radio background, but highly accurate measurements at such frequencies become difficult. Below MHz the effect is suppressed by the induced scattering. We have found the frequency ranges that are optimal for searching for and measuring the Compton radio background excess. We show that hot () clusters at high () redshifts are most promising for its observation. Because of the strong concentration of the bremsstrahlung to the cluster center, the peripheral observations of the Compton excess must be more preferable than the central ones. Moreover, owing to the thermal radiation of the gas and its concentration to the center, the above-noted transition from the "negative" source on the map of background fluctuations to the "positive" one when moving downward along the frequency axis must occur not gradually but through the stage of a "hybrid source"—the appearance of a bright spot surrounded by a dark ring. This form of the source in projection is explained by its unusual three-dimensional shape in the form of a narrow radio bremsstrahlung peak rising from the center of a wide deep hole associated with the Compton scattering of the cosmic microwave background. The scattered radiation from an active central cluster galaxy in the past can amplify the effect. An analogous "hybrid source" also appears on the map of background fluctuations near a frequency of GHz—when passing from the deficit of the cosmic microwave background to its excess (due to the scattered photons). The unusual shape of the source is again associated with the thermal gas radiation. Simultaneous measurements of the radio bremsstrahlung flux from the gas and the amplitude of the distortions due to the radio and cosmic microwave background scattering will allow the most important cluster parameters to be determined. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. Polarization of recoil photon in nonlinear Compton process.
- Author
-
Titov, A. I.
- Subjects
- *
POLARIZED photons , *DIFFERENTIAL cross sections , *QUANTUM electrodynamics , *RELATIVISTIC electrons , *POLARIZED electrons , *COMPTON scattering - Abstract
The polarization of recoil photon ( γ ′ ) in the nonlinear Compton process e + L → → γ → ′ + e ′ in the interaction of a relativistic electron with a linearly polarized laser beam ( L → ) is studied within the Furry picture in the lowest order, tree-level S matrix element. In particular, we consider the asymmetry of differential cross sections A for two independent axes describing the Compton process equal to the intrinsic spin variable ξ 3 f that determines the polarization properties of γ ′ . The sign and absolute value of the asymmetry determine the direction and degree of γ ′ polarization. We have analyzed the process in a wide range of laser intensity that covers existing and future experiments. Our results provide additional knowledge for studying nonlinear multi-photon effects in quantum electrodynamics and can be used in planning experiments at envisaged laser facilities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Pressure Distribution Inside Nucleons in a Tsallis-MIT Bag Model.
- Author
-
Matías Astorga, Manuel A. and Herrera Corral, Gerardo
- Subjects
- *
PARTICLES (Nuclear physics) , *COMPTON scattering , *HADRONS , *QUANTUM chromodynamics , *FACTOR analysis - Abstract
We present a phenomenological framework based on the MIT bag model to estimate the pressure experienced by quarks and gluons inside nucleons. This is accomplished by implementing non-extensive Tsallis statistics for the two-component system. In this model of hadrons, the strong interaction generates correlations effectively described by the q-Tsallis parameter. The resulting hadron pressure exhibits general agreement with recent calculations derived from Lattice QCD. Additionally, we compared this pressure with data extracted from deep virtual Compton scattering experiments and gravitational form factor analyses. The extended bag model provides an alternative interpretation of bag pressure in terms of the q-Tsallis parameter. Consequently, the MIT bag model can be expressed without requiring the inclusion of the bag pressure parameter. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Scattering Polarimetry in the Hard X-ray Range.
- Author
-
Costa, Enrico
- Subjects
HARD X-rays ,POLARIMETRY ,X-ray astronomy ,FOCUS (Optics) ,COMPTON scattering ,GRAZING incidence - Abstract
In one and a half years, the Imaging X-ray Polarimetry Explorer has demonstrated the role and the potentiality of Polarimetry in X-ray Astronomy. The next steps include extension to higher energies. There is margin for an extension of the photoelectric approach up to 20–25 keV, but above that energy the only technique is Compton Scattering. Grazing incidence optics can focus photons up to 80 keV, not excluding a marginal extension to 150–200 keV. Given the physical constraints involved, the passage from photoelectric to scattering approach can make less effective the use of optics because of the high background. I discuss the choices in terms of detector design to mitigate the problem and the guidelines for future technological developments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Very high energy gamma-rays from GRB 180720B and GRB 190829A with external Compton emission.
- Author
-
Barnard, Monica, Razzaque, Soebur, and Joshi, Jagdish C
- Subjects
- *
GAMMA ray bursts , *COMPTON scattering , *COSMIC background radiation , *INVERSE Compton scattering , *RELATIVISTIC electrons , *INTERSTELLAR medium - Abstract
Gamma-ray bursts (GRBs) comprise short, bright, energetic flashes of emission from extragalactic sources followed by a longer afterglow phase of decreased brightness. Recent discoveries of very high energy (VHE, ≳100 GeV) afterglow emission from GRB 180720B and GRB 190829A by the High Energy Stereoscopic System have raised questions regarding the emission mechanism responsible. We interpret this observed late-time emission to be the result of inverse Compton emission of ultrarelativistic electrons in the GRB blast wave in an external radiation field, i.e. external Compton (EC), considering both the wind and interstellar medium scenarios. We present predictions of multiwavelength light curves and energy spectra, ranging from optical to VHE, and include the synchrotron and synchrotron self-Compton (SSC) radiation mechanisms as well. We corrected the EC and SSC models for the gamma-ray attenuation by absorption of photons through their interaction with the extragalactic background light. We compared our results to multiwavelength data and found that EC gives a satisfactory fit for a given set of fixed model parameters for GRB 180720B, whereas SSC results in a better fit for GRB 190829A. For both GRBs, a wind environment is preferred over constant-density interstellar medium, and the cosmic microwave background as the external radiation field. However, with more data and an effective optimization tool we can find a more robust fit of the model, implying better constraints on the GRB environment and the particle energy requirements for the emission observed at late times. This has consequences for future observations of GRBs at these extreme energies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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