What is Gamma radiation: Definition and 34 Discussions

A gamma ray, also known as gamma radiation (symbol γ or


{\displaystyle \gamma }
), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power.
Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts (keV) to approximately 8 megaelectronvolts (~8 MeV), corresponding to the typical energy levels in nuclei with reasonably long lifetimes. The energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 teraelectronvolt (TeV) range have been observed from sources such as the Cygnus X-3 microquasar.
Natural sources of gamma rays originating on Earth are mostly as a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles. However, there are other rare natural sources, such as terrestrial gamma-ray flashes, which produce gamma rays from electron action upon the nucleus. Notable artificial sources of gamma rays include fission, such as that which occurs in nuclear reactors, and high energy physics experiments, such as neutral pion decay and nuclear fusion.
Gamma rays and X-rays are both electromagnetic radiation, and since they overlap in the electromagnetic spectrum, the terminology varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: Gamma rays are created by nuclear decay, while in the case of X-rays, the origin is outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy. This convention stems from the early man-made X-rays, which had energies only up to 100 keV, whereas many gamma rays could go to higher energies. A large fraction of astronomical gamma rays are screened by Earth's atmosphere.
Gamma rays are ionizing radiation and are thus biologically hazardous. Due to their high penetration power, they can damage bone marrow and internal organs. Unlike alpha and beta rays, they pass easily through the body and thus pose a formidable radiation protection challenge, requiring shielding made from dense materials such as lead or concrete.
Gamma rays cannot be reflected off a mirror and their wavelengths are so small that they will pass between atoms in a detector.

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  1. eneacasucci

    I Gamma radiation decay intensity (IAEA nuclide chart)

    I was looking at the gamma radiation data from IAEA's website: (https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html) and was confused by the absolute intensity listed in the page. I Googled it and it seems to be the probability of emission but why it doesn't add up to 100%? For example...
  2. R

    Interpretation of Net Peak Area in Gamma Spectroscopy

    Hello, My question relates to gamma spectroscopy. I understand how the net peak area is calculated for any photopeak. Fortunately, gamma-spec software (e.g., Genie-2000 from Canberra) provides Net peak area and associated uncertainty (for Cs-137 661.7 keV peak, as an example). My question: are...
  3. S

    Calculating the integrated Beta dose in dense materials (radiolysis)

    I have plastic which contains large amounts of Co-60 and Cs-137. I have already calculated the integrated (50k years) deposited dose from the gamma radiation using Monte-Carlo methods (SCALE). I am now interested in the contribution to deposited dose from the Beta emissions. -I am assuming that...
  4. Baroo

    I Gamma and beta radiation in accelerators?

    How ,exactly, are gamma and beta radiations produced in electron accelerators? Is the process for gamma almost the same as X-ray in linear accelerators? What about beta?
  5. Javier Lopez

    I X & G Photon scattering

    In order to calculate X and Gamma shielding of I should like use the NIST XCOM online at https://physics.nist.gov/PhysRefData/Xcom/html/xcom1.html In the Xcom tool it is obtained a graph and table of scattering in cm2/g. In order to calculate as example the shielding from 1e19 gamma rays of...
  6. A

    B Quick Question about emitted radiation and Geiger counter accuracy

    Hi everyone. I read from: https://www.nucleonica.com/Applet/NaturalRA/Button5/page5.html that inside the human body, 4400 of K40 atoms disintegrate every second through radioactive decay. Of this decay, 11% (480) results in gamma radiation, and 50% of that 11% (240) escapes the body. My...
  7. Elvis 123456789

    Collision of alpha with Be -> C + gamma

    Homework Statement Before the discovery of the neutron, it was proposed that the penetrating radiation produced when beryllium was bombarded with alpha particles consisted of high-energy &gamma rays (up to 50 MeV) produced in reactions such as α + 9Be --> 13C + γ a.) Calculate the Q value for...
  8. G

    I Gamma radiation, photon energies and wavelength question

    I haven't though about this from such a perspective but today while reading wikipedia (yes yes not the best source) I got confused, now the "eV" is said to measure the energy gained by an electron between a potential difference of 1V. I assume particle physicists use this measurement because its...
  9. U

    I Background gamma radiation

    I'm trying to find out how much gamma-radiation the average human is exposed too from background radiation. But all I can find are numbers describing the total background radiation, not just the gamma radiation alone. Does anyone know where I can find this information?
  10. moenste

    New distance between the Geiger counter and the source

    Homework Statement A point source of γ-radiation has a half-life of 30 minutes. The initial count rate, recorded by a Geiger counter placed 2.0 m from the source, is 360 s-1. The distance between the counter and the source is altered. After 1.5 hour the count rate recorded is 5 s-1. What is the...
  11. DarkBabylon

    B High energy protons and electrons to gamma radiation

    Can high energy incoming protons and electrons be absorbed and their energies remitted by photons? If so what are the typical ranges of energies emitted and are they heading in the same direction as the original emission if we had a sheet of metal being bombarded by those protons and electrons?
  12. A

    Determine half life from gamma radiation

    I'm working on a lab and the task is to determine the half life of an element studying the beta radiation or the gamma radiation (emitted from the daughter). I have all the data and I'm done with the beta part, that was pretty straight forward. I have no clue how to relate the gamma radiation to...
  13. O

    I How long can you be exposed to gamma radiation for

    So my question is, how long can you be exposed to a gamma radiation for? Specifically, I've been working with a sealed cobalt-60 source for a final presentation. Now my professor noted to me that these sources we're using aren't radioactive enough to cause us any harm. However, I've been...
  14. B

    Linearising an Inverse Square Law Graph for Gamma Radiation

    1. Homework Statement A piece of work I am doing for college (UK college that is) has me investigating the inverse square law for gamma radiation. I have collected data and the graph comes out looking right. I want to create a linearised graph of the data to investigate the results further. If...
  15. D

    Help Solving Physics Exam Question on Gamma Rays Counting Rate

    Hi, I came across a question in an exam which I couldn't really relate to any topic of physics, that I had studied. It goes like this- A detector is used to count the number of gamma rays emitted by a radioactive source. If the number of counts recorded in exactly 20 seconds is 10000, the...
  16. 2

    How can metastable isotopes exist?

    I thought I would ask this question in the quantum mechanics section as I presume it has something to do with QM, like the reason why alpha and beta decay do not happen immediately but instead there is a half life for this decay. My understanding is that with alpha decay, the strong nuclear...
  17. Qw_freak

    Calculation of gamma ray shielding value in liquids?

    Hi folks Please bear with me, I'm new here and this may not be the correct forum to ask this question. If this is the case, I'll of course remove my question and ask it the appropriate place instead. However, here it goes: I need to be able to calculate how much a given intensity of gamma...
  18. S

    Migration Path of Electrons in Ionized Air (Gamma Radiation)

    I would love some clarification on a gamma ray process. This is what I understand so far: Electrons are accelerated at 19MeV at a cathode which is releasing gamma ray photons with an energy of 1.9MeV. Is it possible to generalize the emission number of photons (roughly) to be equal to the...
  19. M

    Radioactive Source Emitting Only Alpha and Gamma Radiation

    Homework Statement "How could you show that a radioactive source was only emitting alpha and gamma radiation?" The attempt at a solution This really stumped me...obviously they have different penetration distances, and different strengths of ionisation, but I don't know how to show that...
  20. M

    Absorption of Gamma Radiation

    After performing this experiment, we will get different peaks on the computer screen, where on x-axis lies thickness of the absorber and on the y-axis the nb of channels. What do these represent exactly? Why do we have a high peak and a medium sized one? What are the significances of each...
  21. B

    Is there a material that can emit gamma radiation when heated by electricity?

    Different materials emit different frequencies of radiation when heated by a source of heat such as electricity. Examples include gases and solid filaments that emit infrared, visible and ultraviolet radiation, and the scheelite calcium tungstate filaments used to produce x-rays in fluoroscopes...
  22. B

    How strong is gamma radiation ?

    Several elementary particles emits gamma radiation Where can I read more about the different magnitude?
  23. S

    The effects of the alpha, beta and gamma radiation on humans

    I have had a great deal of trouble finding sources that are specific as to how exactly radiation damages the body, it usually just says what damage radiation causes but not how it causes it, so I have compiled what I have found and I want to know if it is accurate and to fill in sequence of...
  24. G

    Gamma radiation. Nuclear, electromagnetic or both?

    I know that gamma rays are a part of the electromagnetic spectrum and that they are also a type of nuclear radiation, created upon the decaying of a large, unstable nucleus. Is there any difference between these 2 definitions of gamma radiation? Is gamma radiation only created in the way...
  25. R

    Gamma radiation decay question.

    Homework Statement The radioactive substance emits gamma radiation. Complete the equation below for the disintegration of the nuclei of this substance. Homework Equations ^{24}_{11}Na^{*} \rightarrow ^{?}_{?}Na + ? The Attempt at a Solution ^{24}_{11}Na^{*} \rightarrow...
  26. PhysicoRaj

    Why only gamma radiation ?

    Why only gamma radiation...? All the radioactive elements emit either alpha, beta, never both and maybe sometimes gamma with these. But why do they emit gamma rays only? Why not X-Rays?
  27. T

    Gamma radiation photoelectric effect

    I read earlier that the photoelectric effect is when electromagnetic radiation essentially overcomes an electrons binding energy and converts it to electricity, which is how solar panels function. But why is it that gamma radiation isn't being used to capture energy? If gamma radiation has a...
  28. daisey

    Gamma Radiation: How Does It Pass Through & Damage the Body?

    Question about Gamma Radiation. I understand that Gamma Radiation, like X-Rays, are just photons (light particles) at different frequencies. I was reading an article about the Nuclear Plant problems in Japan, and the article stated that photons from Gamma Radiation for the most part pass...
  29. T

    Gamma radiation sorce sheilding

    Homework Statement a gamma raidiation source (226Ra) is used in hospital laboratory. if shielding is considered as a means of control how many centimeters are needed to reduce the radiation to 1% of what a worker would be exposed to without shielding? assume the shield material is a)...
  30. K

    How much Gamma Radiation does Radium produce

    Alright, I've confirmed that Radium produces Gamma rays. But how much does it put off? Is it a really high level or a tolerable level that can be stopped.
  31. M

    Exploring Gamma Radiation in the Nucleus

    [SOLVED] Gamma radiation gamma radiation does anyone know how it is produced within the nucleus? and I know that gamma radiation takes place after a isotope has undergone a decay and is in an excited state. I know that what interest me is the very nature of the excited state! and how the...
  32. O

    Splitting of Eu characteristic L gamma radiation in EDX analysis?

    Haven't been able to find the answer anywhere IRL yet, so I thought I'd see if someone in the PhysicsForums could help me with this one. When doing SEM/EDS (EDX/EDXS) (~equivalent to x-ray fluorescence) analysis it looks as if my europium containing samples contain copper as well, which'd...
  33. wolram

    Natural Gamma radiation from Earth

    http://www.sciencedaily.com/releases/2005/05/050502190314.htm ScienceDaily (May 2, 2005) — DURHAM, N.C. -- Duke University engineers have led the most detailed analyses of links between some lightning events and mysterious gamma ray emissions that emanate from Earth's own atmosphere. Their...
  34. J

    Gamma radiation bursts GBE's

    About gamma radiation bursts What if the bursts we observe are the light equivalent of a sonic boom? The energy report of an object surpassing the speed of light. These could be tell tale signs of superluminal or warp travel. As an oblect reaches the speed of light, light would be compressed...