I have this problem:

The Stanford Linear Accelerator can accelerate electrons to 50 GeV What is the minimum wavelength of photon it can produce by Bremsstrahlung? Is this photon still called an x ray?

I have solved the problem to get $\lambda = 2.48\times 10^{-17}$m but I have problems with the last question because the wavelength is not the wavelength for x rays, however in the solution of the problem it is said that every photon produced by Bremsstrahlung is an x ray, even if it doesn't have the wavelength of x ray, Is that true?


1 Answer 1


You have a definition or terminology issue, not a physics issue:



There is no consensus for a definition distinguishing between X-rays and gamma rays. One common practice is to distinguish between the two types of radiation based on their source: X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus.[56][57][58][59] This definition has several problems: other processes also can generate these high-energy photons, or sometimes the method of generation is not known. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength (or, equivalently, frequency or photon energy), with radiation shorter than some arbitrary wavelength, such as 10−11 m (0.1 Å), defined as gamma radiation.[60] This criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. (Some measurement techniques do not distinguish between detected wavelengths.)

For the purposes of passing your tests, I suppose it is best to use the definitions implicit in your textbooks or notes, but you should be aware of the ambiguity.

  • $\begingroup$ Also for long wavelengths. Synchrotrons can be used as a source for infrared spectroscopy. I would not call them x-rays, but it is Bremsstrahlung. $\endgroup$
    – user137289
    Nov 13, 2018 at 8:39

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