Spectrum Recorder PCI-E Card?

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Harald_Consul
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Spectrum Recorder PCI-E Card?

Post by Harald_Consul » Sat Jan 26, 2019 4:12 pm

In the thread "Integrated Lab Measuring and Controlling (Labview, Labjack, ...)" we have already figured out, that high-frequency analysis is pretty costly.

For cost effectiveness I am interested in recording only (without any analyzing features) of a raw high-frequency signal from a scintillation tube.

Is there some kind of spectrum recorder PCI-E card (ideally with 16 bit A/D converter), that could ship round about 90 Gbit/s (5 Gsample/s * 16 bit) directly to an NVMe SSD (NVMe solid state disk)? (I mean like a spectrum analyzer, however recording only.)

Other computer interfaces like USB or Ethernet are much to slow for 90 Gbit/s. The next best popular interface would be 10Gbit Ethernet. However, there are no 10Gbit Ethernet spectrum analyzer or oscilloscopes on Ebay, either.

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Re: Spectrum Recorder PCI-E Card?

Post by Chris Mullins » Sat Jan 26, 2019 5:09 pm

5 Gsamples/sec at 16 bits is extremely high performance - I'm not sure you'd find something like that off the shelf at any price.

Here's one source of more "reasonable" PCIe boards: http://ultraviewcorp.com/displayproduct.php?cat_id=1, they have a 12-bit 2Gsample/sec board: http://ultraviewcorp.com/displayproduct ... 1&sub_id=8, at only $19,000.

If you can settle for 12 bits, you might be able to roll your own by combining the AD9213 eval board (https://www.analog.com/en/design-center ... d9213.html) and the ADS8-V1EBZ data acq. board: https://wiki.analog.com/resources/eval/ads8-v1

More info on that AD9213 a/d converter: https://www.electronicsweekly.com/news/ ... s-2018-05/. Apparently the chip itself is over $3,600, so you're still in the 5 digit price range.

I don't think the PC interface is the (most) limiting technology here.

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Re: Spectrum Recorder PCI-E Card?

Post by Harald_Consul » Sun Jan 27, 2019 11:00 am

Thanks Chris.

As you gave me the right key words, I did another Ebay search now:

(A/D, data-acquisition) (card, board) (PCIe, PCI-E, PCI-Express) @ Ebay

However, I did not find a 16 bit 5GSample Card in the range of 1000 USD.

So, how about a forum maker project "Spectrum Recorder PCI-E Card"? ;-)

I guess, a core metal 16 bit 5GSample A/D converter chip would be about 10 USD. Why wasting money, if we could do ourselves even better?

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Re: Spectrum Recorder PCI-E Card?

Post by Chris Mullins » Sun Jan 27, 2019 1:20 pm

Harald,

Most of the devices from your ebay search are audio A/D devices, sampling at 192 kHz.

I don't think you understand how extreme 16 bits at 5 Gsamples/sec is with the current state of the art. I doubt ANYONE makes something with those specs, at ANY price, at least not as an off-the-shelf product.

Your guess of $10 for an A/D chip with those specs is WAY off. The link I gave above for the new AD9213 chip (which is only 12 bits) mentions a $3,600 price tag just for the chip.

Here's an article about some A/D chips with more "relaxed specs" - 14 bits, and 625 to 1300 Msample/sec: https://www.eenewsembedded.com/news/14- ... iondefence

Note that prices JUST FOR THE CHIP range from $406 to $11,108 each, in thousand piece quantities.

If you want a quick survey of A/D chips available for easy purchase, try this Digikey link: https://preview.tinyurl.com/y95k5x2o. I narrowed it down to A/D converters in stock, sampling at 1Gsample/s and above. You can see the number of bits ranges from 7 to 16, with prices ranging from $168 to $4400.

A complete A/D system built around one of these will be very expensive, and a real engineering challenge to design (or even fully test). There's a reason why those A/D boards are so costly.

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Rich Feldman
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Re: Spectrum Recorder PCI-E Card?

Post by Rich Feldman » Mon Jan 28, 2019 5:28 am

Harald, the term Spectrum Recorder in your topic title leaves me confused.

Do you mean Spectrum in the sense of an electronic signal waveform (e.g. Fourier transform), as hinted by your link to a spectrum analyzer page? Why would that kind of spectrum at output of a scintillator-coupled PMT be of interest, unless the intensity of radiation is varying rapidly and periodically?
Or Spectrum in the sense of energy distribution in ionizing radiation? To get the latter from a scintillator-and-PMT signal, each signal pulse is reduced to one number, that has nothing to do with the frequency content of the PMT output waveform.
Either way, there's no "spectrum" you can capture with an ADC.

Please excuse me for guessing that you mean the radiation energy spectrum. Sounds like you want to digitize the pulses as if you were viewing them with an oscilloscope, with plenty of samples for each pulse. Then compute the pulse areas. That's doing it the hard way, unless you already have the oscilloscope -- and oscilloscopes don't digitize to 16 bits or even, generally, 12 bits.

Unless I've overlooked details of your application, why not quantize PMT pulses the way most people do it? Analog front end converts the PMT pulse to one whose height can be detected, or shape sampled, with much slower electronics. Without loss of "energy" resolution. Doesn't Gamma Spectacular (among others) send the scaled pulses to a PC audio input for digitization?
scint.JPG
image from http://amptek.com/products/dp5g-oem-dig ... -and-pmts/

I just learned that sometimes the PMT pulse shape, not just its area, is different for different kinds of radiation. Paying attention to that would put you ahead of 99% of the applications for ionizing-radiation spectral measurement, in my unpracticed opinion.
Mike echo oscar whisky! I repeat! Mike echo oscar whisky, how do you copy? Over.

Harald_Consul
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Re: Spectrum Recorder PCI-E Card?

Post by Harald_Consul » Mon Jan 28, 2019 3:07 pm

Yes. That's exactly the inaccuracy problem.

A multi-channel-analyzer for a scintillator (consisting out of a transformation crystall and a photo multiplier tube inside) counts each bandwith of volt amplitudes (e.g. 10,5 mV - 11,5 V) separatly. Each amplitude corresponds to a certain energy of a particle.

However, when 2 particles hit the crystall at the same time, the sum of the resulting voltage falls in a different volt bandwith is counted like as it would have been from one particle with higher energy.

Thus, I want to capture the raw data to resolve for the particles much more sophisticated by a statistical software. (I am a statistician, remember?)

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Re: Spectrum Recorder PCI-E Card?

Post by John Futter » Mon Jan 28, 2019 6:14 pm

Harald
this is the bane of nuclear physics
cured by backing away to keep deadtime very low - inverse square law
(deadtime = rejected counts due to two or more arriving within the integration time)
You can also use differing scintillators that are much faster in decay time so shaping time is coresspondingly much shorter such as LYSO and BGO.
Note that most MCAs use PGA's to get the data in an almost parrallel fashion into memory something that a processor cannot do

We use these at work https://www.fastcomtec.com/products/mpa/mpa4/ and these are more than fast enough for beam on target work such as proton microprobe, PIXE, PIGE, RBS, and NRA with LYSO BGO GeLi SiLi detectors note we tend not to use NaI detectors for this work due to afterglow - these are better suited to low background counting where afterglow does not happen

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Re: Spectrum Recorder PCI-E Card?

Post by Steven Sesselmann » Mon Jan 28, 2019 11:38 pm

Hello Harald,

At the recent IEEE in Sydney I was talking with one of the exhibitors from Hawaii who explained that they design and make ADC's with Giga Bit sampling, might be something.

http://www.naluscientific.com


Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG

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Re: Spectrum Recorder PCI-E Card?

Post by John Futter » Tue Jan 29, 2019 3:12 am

As Steven has pointed out yet another offering using gate arrays to get gigabit equivalent input
And looking at thier enduse I would say they are eye wateringly expensive almost custom tfor the LHC

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Re: Spectrum Recorder PCI-E Card?

Post by Harald_Consul » Tue Jan 29, 2019 2:33 pm

I see,measurement technology is unbelievable expensive in comprehension to other electronic equipment.

Maybe I could use some nerd raw data acqusition equipment like a software defined radio.

The features of the offered software defined radio are:
  • 1 MHz to 6 GHz operating frequency
  • up to 20 million samples per second
  • 8-bit quadrature samples (8-bit I and 8-bit Q)


Meanwhile I have figured out, that the signal amplitude of a (negative voltage) scintillation tube typically is in the range of
~20 mV with a pulse length of ~20 ns.

1/0.00000002s = 50'000'000 Hz

So, 6 GHz would be fine, but 20 million samples per second is too slow, right?

What would be a good sampling rate (#samples/second) to measure a 20 ns signal, in order to separate the mixed combined voltage amplitudes from multiple particle events into true single particle events (respectively their voltage amplitudes)?

P.S.: If you are not telling me, I have to buy the software defined radio and figure out myself, I guess. ;-)

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