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I Analyzing signals from a radioactive source

  1. Mar 28, 2017 #1
    Hello All,
    Is it possible to analyze signals/photons/pulses from a 57Co source (strength 2 microCi) using a ADC (multihit readout) with 5 GS/sec? Just to look at pulse height spectrum..also I am interested to make a coincidence counting between 122 adn 14.4 keV levels! I heared that these ADCs are used to count pulse duration of less than 20 ns. But 57Co sources emits pulses in the order of microsec.
    Thanks for your input.
  2. jcsd
  3. Mar 28, 2017 #2


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    It will depend on what kind of detector you are using; the ADC itself can't detect pulses directly.
    Also; what do you mean by "pulse duration" in this context? I assume you are interested in gamma radiation in which case there IS not pulse duration as such (only single photons which do not have a "shape"); the pulse shape will depend entirely on the properties of the detector.
  4. Mar 28, 2017 #3
    Yes I use NaI(Tl) detectors. Can I connect these detectors to ADC with 5 GS/sec? Will it work? When you view the signals from detector using a oscilloscope, the pulses look as in page 71 of this pdf document http://www.lanl.gov/orgs/n/n1/panda/00326399.pdf. The x-axis scale is what I meant as pulse duration..in that fig it is 50microsec.
  5. Mar 28, 2017 #4

    Vanadium 50

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    If your pulse width is 50 us, or 50,000 ns, having 20 ns time resolution will not help you much.
  6. Mar 29, 2017 #5


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    You're going to want to amplify your signal before putting it into an ADC, this is described in the document you provided and is a standard procedure and will give a nice signal as shown in fig 4.6. The pulse duration isn't to do with 57Co itself, it's the time response of the detector. A standard spectroscopy amplifier and ADC will have no issue with this.

    If you wish to look at coincidences, you'll have to do some more complicated electronic setup than you are attempting at the moment, for a start, you'll need multiple channels in which to do a coincidence.
  7. Mar 29, 2017 #6
    Hello, vanadium/e.bar.qoum:
    Yes I want to set a coincidence instrument. 122 keV as start signal (it is the start of the emission of 14.4 kev) and 14.4 keV as stop signal. Although, I have CFDs, SCAs, TAs, etc, I prefer to use the flash ADC with 5 GS/sec. So thought of asking help! Some say it is only possible with conventional NIM modules..Is it true?
    PS: How coincidence setup are done? How the signals are selected using TAs, CFDs, TACs,? Any info/materials/books for this works with pictures and exmaples..
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