Theoretically predicted fundamental features in the process of resonant spontaneous bremsstrahlung radiation during the scattering of ultrarelativistic electrons with energies of the order ∼ 100 GeV by the nuclei in strong laser fields with intensities up to I ∼ 1024 W cm−2. Under resonant conditions, an intermediate electron in the wave field enters the mass shell. As a result, the initial second-order process by the fine structure constant is effectively reduced to two first-order processes: laser-stimulated Compton effect and laser-assisted Mott process. The resonant kinematics for two reaction channels (A and B) is studied in detail. An analytical resonant differential cross-section with simultaneous registration of the frequency and the outgoing angle of a spontaneous gamma-quantum for channels A and B is obtained. The resonant differential cross section takes the largest value with a small number of absorbed laser photons. In this case, the resonant cross-section is determined by one parameter, depending on the small transmitted momenta, as well as the resonance width. In strong fields, spontaneous gamma quanta of small energies are most likely to be emitted compared to the energy of the initial electrons. At the same time, the angular width of the radiation of such gamma quanta is the largest. With an increase in the number of absorbed laser photons, the resonant cross-section decreases quite quickly, and the resonant frequency of spontaneous gamma quanta increases. It is shown that the resonant differential cross-section has the largest value in the region of average laser fields (I ∼ 1018 W cm−2) and can be of the order of ∼ 1 0 19 in units Z 2 α r e 2 . With an increase in the intensity of the laser wave, the value of the resonant differential cross-section R r e s max decreases and for the intensity I ∼ 1024 W cm−2 is R r e s max ≲ 1 0 7 in units Z 2 α r e 2 . The obtained results reveal new features of spontaneous emission of ultrarelativistic electrons on nuclei in strong laser fields and can be tested at international laser installations.
The actual theoretical research investigates the resonant spontaneous bremsstrahlung (RSB) of ultrarelativistic electrons under the condition of scattering on a nucleus in the field of a weak electromagnetic wave. The progression of the functional mechanism indicates the transformation of the intermediate virtual electron into the real particle state. As a result, the initial second order process with accordance to the fine structure constant in the light field productively splits into two consequent first order formations: the laser-stimulated Compton effect and the laser-assisted scattering of an electron on a nucleus. Precise examination specifies the resonant kinematics of the RSB system that designate the phenomenon of the initial and final electrons with addendum of spontaneous high-energy photon propagation in the narrow angle cone. Furthermore, it is important to emphasize that the resonance escalation possesses a possibility to develop within two reaction channels. Thus, the first channel delineates the occurrence that correlates to the spontaneous photon emission by an electron (laser-stimulated Compton interaction) with subsequent scattering on a nucleus (laser-assisted Mott procedure). The second channel illustrates the configuration corresponding to the electron scattering on a nucleus with consecutive spontaneous photon emission in the wave field. Therefore, with implementation of the equivalent elementary criteria the value of the resonant frequency for the first channel perpetually represents a deteriorative counterpart to the second alternative. Moreover, the spontaneous photon radiation angle allocates a single-valued dependency with the resonant frequency for the first channel in contrast to the second displacement that categorizes a composite area with three various resonant frequency magnitudes for the particular emission angle diapason. The project data analysis proposes that the reaction channels do not interfere within the whole range of observation with a specific evaluation for the particles propagation at zero scattering angle. As a result of the investigation the calculations determine the scattering differential cross-section of the resonant construct development. To summarize, the particular cross-section within the resonant ambience significantly exceeds the according cross-section in the approximation of an external field absence. In conclusion, numerous scientific facilities with specialization in pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS) may experimentally validate the computational estimations.
The resonant photoproduction of ultrarelativistic electron-positron pairs (PPP) in a nuclear field and a weak laser field is theoretically studied. Under resonance conditions, the intermediate virtual electron (positron) in the laser field becomes a real particle. As a result, the initial process of the second order in the fine structure constant in the laser field effectively reduces into two successive processes of the first order: single-photon production of electron-positron pair in a laser field (laserstimulated Breit-Wheeler process) and laser-assisted process of electron (positron) scattering on a nucleus. Resonant kinematics of PPP is studied in details. It is shown that for the considered laser intensities resonance is possible only for the initial photon energies greater than the characteristic threshold energy. At the same time, the ultrarelativistic electron and positron propagate in a narrow cone along the direction of the initial photon momentum. The resonant energy of the positron (electron) can has two values for each radiation angle which varies from zero to some maximum value determined by the energy of the initial photon and the threshold energy. Resonant differential cross section of the studied process was obtained. It is shown that the resonant differential cross section of the PPP can significantly exceed the corresponding cross section of the PPP without an external field. The project calculations may be experimentally verified by the scientific facilities of pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS).
This article focuses on the resonant high-energy spontaneous bremsstrahlung of ultrarelativistic electrons with considerable energies E i ≳ 10 2 GeV in the field of a nucleus and a quasimonochromatic laser wave with an intensity I ≲ 10 16 ÷ 1017 W cm−2. Under resonant conditions within the light field the intermediate virtual electron transformed into a real particle. Therefore, the initial second order process in accordance with the fine structure constant in the laser field effectively reduced to two successive processes of the first order: the laser-stimulated Compton-effect and laser field-assisted scattering of an electron by a nucleus. In this work we derive the expressions for the resonant differential cross-sections of this processes using the simultaneous registration of the frequency and outgoing angle of the spontaneous photon and the absorption of the rth wave of photons (where r = 1,2,3,...is the resonance number). To summarize, for the first resonance of channel A, the resonant differential cross-section attains a magnitude of the ∼1012 and the third resonance of channel B attains ∼105 in units of α Z 2 r e 2 ( c m 2 ) . Finally, scientific laser pulse radiation (SLAC, FAIR, XFEL, ELI, XCELS) can be used to verify the model calculations.
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