# Bremsstrahlung X-Rays Motivation: Understanding how [[How X-Rays are Made in X-Ray Tubes]].  ## What is Bremsstrahlung? Bremsstrahlung, or braking radiation, is the process of when an electron approaches a target nuclei, and curve around it. As it curves, it also has to "brake" and slow down as a result of the positive charge of the nucleus. As it slows down, the electron loses energy and must emit a photon in order to maintain the laws of conservation of energy. This emitted photon is a bremsstrahlung x-ray. And it is an x-ray and not a $\gamma$-ray because [[X-Rays are Radiation from Electrons]], while $\gamma$-rays are from nuclear processes [^1]. [^1]: Knoll Radiation 4th Edition Bremsstrahlung x-rays are emitted at a continuum of energies, meaning that they cannot be used for calibration purposes, and generally require additional engineering in order to use them in the field of energy spectroscopy. However, the shape of the energy spectrum can be managed by filtering out lower energies with appropriate absorber materials. The energy of the photon emitted is easily calculable as just the difference between the starting energy and the ending energy of the electron. $h\nu = E_1 - E_2 $ The linear specific energy loss from this radiative process is given roughly as: $-\left(\frac{dE}{dx}\right)_r = \frac{NEZ(Z+1)e^4}{137m_0^2c^4} \left(4 \,\text{ln}\,\left[\frac{2E}{m_0c^2}\right] - \frac{4}{3} \right) $ ## Sources Bremsstrahlung X-rays are generated from [[X-Ray Tubes]], where electrons are accelerated in a vacuum by an electric field towards a target anode. The output spectrum is a continuous spectrum with some sharp peaks from [[Characteristic X-Rays]] of the target anode. the shape of the spectrum is given by [[Kramers' Law]]. ## Closing Thought As an unrelated anecdote, my first ever "true" nuclear engineering course was taught to me by a man with a very thick German accent, and he joked how this made him the perfect teacher for the course whenever he talked about "Bremsstrahlung". Thanks Dr. Schmitz.