Bremsimpulse

Bremsimpuls, in the context of particle and radiation physics, refers to the momentum transfer associated with the emission of bremsstrahlung radiation. The term describes the recoil and momentum balance that accompany the deceleration or deflection of a charged particle as it interacts with the electromagnetic field of another particle, typically a nucleus or atomic electron.

In a bremsstrahlung process, a charged particle such as an electron loses energy by radiating photons while changing its trajectory in the Coulomb field of a target. Conservation of momentum requires that the momentum carried away by the emitted photon(s) is accompanied by an equal and opposite impulse imparted to the radiating particle and, if applicable, to the scattering center (the nucleus or surrounding medium). Thus, the bremsimpuls encompasses the net momentum transferred to the emitting system and to its surroundings during the radiation event.

Quantitatively, if an electron with initial momentum p_i emits a photon with momentum k and ends with p_f, the impulse exchanged with the target satisfies Δp = p_i − p_f − k. The magnitude and direction of this impulse depend on the photon energy and emission angle, as well as on the mass and recoil of the scattering center. In practice, the recoil to a heavy nucleus is typically small due to its large mass, but it is essential for accurate momentum balance in high-precision measurements.

Bremsimpuls is relevant for understanding energy-loss mechanisms in matter, detector design, and various applications in medical physics and astrophysics where momentum conservation in radiative processes matters. See also: bremsstrahlung, Bethe-Heitler theory, radiation reaction.