Quantum modifications in magnetic bremsstrahlung

Abstract

The relativistic classical expression for the magnetic bremsstrahlung (synchrotron) spectrum of electrons can be generalized to include first-order quantum corrections by the replacement (I(ω) ∼ κ(ω/ω0) → κ((ω/ω0)[1 + (ħω/E)]) where κ(z)=z∫s∞dxK5/3(x), and ωc is related to the electron energy and magnetic field intensity by ωc(keV) ⋍ 0.06 E2 (GeV) H(kG). These first-order shifts are of negligible significance unless E (GeV) Prompted by the results of a megagauss bremsstrahlung experiment, we have recalculated the synchrotron process including all relevant second-order quantum corrections. In the range the analysis reduces to the simple correspondence I(ω) → κ((ω/ωc)[1 +ħω/E][1 − (ħω/2mc2)2]3/2), which exhibits the surprising feature that the second-order terms can be more significant than the first-order corrections. In fact whenever E2 (GeV) the general results indicate that the spectrum is drastically altered by quantum effects. Since the second-order terms are also linked with an enhancement of the magnetic trident production rate, the matrix elements are evaluated with sufficient generality to allow for inner bremsstrahlung processes.