What is energy resolution

  1. Can someone explain the concept of energy resolution to me, especially in gamma cameras. Thanks.
  2. jcsd
  3. Astronuc

    Staff: Mentor

    Where did one find a reference to gamma cameras?
  4. Well, l am reading a thesis on them and the author keeps on referring to energy resolution as a % FWHM. So l really don't understand what this means.
  5. Generally speaking, energy resolution refers to the degree of monochromaticity. So if we say the particles have an energy say e, actually they are not all the same energy rather they are spread in a gaussian distribution around e with e representing the mean. The smaller the sigma of the distribution, the higher the energy resolution and the bigger the sigma the lower the energy resolution. % FWHM (~2.35σ ) is often used instead of sigma to represent the resolution especially since the distribution is not always gaussian but can be lorentzian or a mixture.

    Last edited: Jun 13, 2012
  6. So generally speaking, the lower the %FWHM the better the camera is ?
  7. mfb

    Staff: Mentor

    A smaller FWHM might come with some disadvantages elsewhere, but in general, a smaller value there gives a better energy resolution, which can help in the analysis.
  8. FWHM means Full Width at Half Maximum. When talking about the resolution of a detector, this means that a beam of monochromatic=monoenergetic photons or particles will produce a Gaussian (or other) distribution of *detected* (or apparent) energies.

    In spectroscopy this is significant, as it is sometimes necessary to distinguish gamma lines with close-by energies. If, roughly speaking, the resolution is worse than the energy difference, then the detector cannot tell the lines appart.

    For many detectors, the resolution is related to the energy of the detected particle or photon. That is why the FWHM is given as percentage of the particle's energy.
  9. Astronuc

    Staff: Mentor

    Is this related to synchrotron radiation imaging or gamma ray imaging/tomography?
  10. It is related to gamma ray imaging.
  11. ZapperZ

    ZapperZ 30,731
    Staff Emeritus
    Science Advisor
    Education Advisor

    In the future, you really should provide as much information, including exact citation to your sources, as possible, rather than giving annoying bits and pieces.

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