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Harvesting Gamma Radiation ? — Parallax Forums

Harvesting Gamma Radiation ?

TubularTubular Posts: 4,702
edited 2011-08-02 03:17 in General Discussion
I just read an interesting article in the June Elektor, about using a blindfolded BPW34 photodiode to detect Gamma Radiation. The BPW34 is reverse biased and its charge amplified for viewing on a CRO. The BPW34 is covered with kitchen foil to prevent photon caused signals from overwhelming those due to gamma/beta radiation.

Having spent the day harvesting energy from various high impedance sources, I have to ask - what quantity (or ballpark qty) of energy is put out by each gamma impact event ?

Could this be harvested somehow?

Comments

  • ElectricAyeElectricAye Posts: 4,561
    edited 2011-07-31 08:34
    It's true that gamma rays can be converted to useful energy much like photons. In fact at least one organism has figured out how to utilize it.

    http://www.technologyreview.com/blog/duncan/17611/

    Also, you might have a look at this:

    http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)


    bon appetit
  • kwinnkwinn Posts: 8,697
    edited 2011-07-31 12:04
    Gamma radiation covers a fairly wide range of energy. Below are energies or some commonly used isotopes:

    Iodine 125 ~ 35KeV
    Cobalt 57 ~ 122KeV
    Technetium 99 ~ 140KeV
    Cesium 137 ~ 662Kev

    One MeV (Million electron Volts) is 1.602x10 -13 Joules. It requires 1 J to heat one gram of dry, cool air by 1 degree Celsius. It would take a fair amount of radioactive material to produce a useable amount of energy.

    Cosmic rays have a wider range of energies and using them for energy suffers from the same problems as solar energy. Converting gamma rays to energy requires expensive hardware and collectors that cover a large area.
  • TubularTubular Posts: 4,702
    edited 2011-07-31 14:14
    Fascinating reading ElectricAye, thanks. Fungus, hmm.

    Thanks kwinn. Some spacecraft convert energy from decaying sources, wonder how they do it.

    I guess I should also post the links from the end of the Elektor article,
    Maxim Application Note 2236
    PIN photodiode-based X- and gamma-ray detectors, by Erhan Emirhan & Cenap S. Oezben
    An Introduction to Semiconductor Radiation Detectors, by C.W.Thiel
  • skylightskylight Posts: 1,915
    edited 2011-07-31 14:38
    It all makes sense now mushroom clouds,radiation
  • ElectricAyeElectricAye Posts: 4,561
    edited 2011-07-31 14:55
    Tubular wrote: »
    ...Some spacecraft convert energy from decaying sources, wonder how they do it. ...


    Tubes,

    they use one of these, which converts the heat byproduct, not the nuclear particles per se, into electricity:

    http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2011-08-01 10:16
    Gammas are relatively hard to capture. They have a low chance of interaction with matter that they pass through, but when they do interact, they can really do some damage.

    The thermoeletric generator in the link electricAye posted uses strontium-90, a beta (electron) emitter, and electrons are easier to capture within a self-contained device without thick layers of lead.

    Another possible thermoelectric source is Americium, an alpha (proton, helium nucleus) emitter, and alpha particles do not travel very far at all in matter, even in air, before their energy is recaptured and turned to heat. A problem is, the element is relatively rare. There are several schemes to use Americium in space. (see the wiki).

    You might think you could capture charge from the core of an ionization smoke detector, which contains about 1 microcurie of Americium-241. After all, one microcurie emits 37000 alpha particles per second. That might sound like a lot, except when you divide it by the amount of charge movement necessary to make an ampere, it comes out as 12 fA. That is 12E-15 A. The individual alpha particles that come off of Americium carry a lot of energy, about 4.5 million electron volts (compare to its occasional gamma ray at 60keV). A smoke detector works because those high energy highly charged particles have high probability of knocking electrons loose from atoms and molecules that they pass near. It takes 34 eV to ionize a molecule of air, so each high energy alpha particle leaves behind a track of over 100000 ionized air molecules. Multiply that times 37000 tracks per second, and there are a lot of ions floating around to act as charge carries. A 9V potential difference across the chamber that contains all of those charges yields a current that is a good fraction of a microamp.
  • Capt. QuirkCapt. Quirk Posts: 872
    edited 2011-08-02 00:07
    My college physics professor was involved in this project TIGRE

    As Dr Tracy Allen said "Gammas are relatively hard to capture" That is what fascinated me about this project. All the hand built boards, and custom IC's used for the project. Not to mention, how years work can be trashed by a gust of wind during before this UC Berkley balloon leaves the ground.


    -> Dr Allen; I just noticed your location, were you involved with the UCB telescope?
  • Mark_TMark_T Posts: 1,981
    edited 2011-08-02 03:17
    The only application I can think of is a PSU for a radiation monitor!
  • JoanJoan Posts: 1
    This is pretty much off y'all subject - but can any of you tell me if it is possible to have an amount of radiation by a gamma scan and then covert it to see how much alpha is present? so for example if i have a gamma scan with 7.51 pci/l of Americium - how much would I have in Alpha?
  • kwinnkwinn Posts: 8,697
    Not quite that simple. See https://en.wikipedia.org/wiki/Americium-241.
  • Tracy AllenTracy Allen Posts: 6,664
    It's highly unlikely that Americium is part of a medical scan. It is primarily an alpha emitter, whereas medical evaluation and therapies are done with gamma or beta emitters. There is no conversion of gamma (electromagnetic radiation) to alpha (a sub-light-speed helium nucleus). Alpha particles that can do huge damage to nearby living tissues, but their effect falls off rapidly as they interact with matter.
  • ercoerco Posts: 20,256
    Please email my friend below, who is fairly knowledgeable in such matters.

    bruce.banner@hulk.com

    Tell him erco sent you.

  • kwinnkwinn Posts: 8,697
    Tracy Allen wrote: »
    It's highly unlikely that Americium is part of a medical scan. It is primarily an alpha emitter, whereas medical evaluation and therapies are done with gamma or beta emitters. There is no conversion of gamma (electromagnetic radiation) to alpha (a sub-light-speed helium nucleus). Alpha particles that can do huge damage to nearby living tissues, but their effect falls off rapidly as they interact with matter.

    Medical scans are primarily Technetium-99m, and in some cases Iodine125. Both are primarily gamma emitters, and it is the gamma that is used for imaging or being counted.
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