ProSpect (Canberra) quick guide

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Steven Sesselmann
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Re: ProSpect (Canberra) quick guide

Post by Steven Sesselmann » 28 Sep 2015, 16:59

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rodorr
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Re: ProSpect (Canberra) quick guide

Post by rodorr » 29 Sep 2015, 05:46

Steven,

Thanks for the info. I grabbed a Mac and had no problems watching the video. I had been using a Windows machine with Firefox and it just didn't seem to like the video format. Thanks again.

Bob
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rodorr
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Re: ProSpect (Canberra) quick guide

Post by rodorr » 01 Oct 2015, 13:03

Pieter or anyone one else for that matter,

Regarding the ProSpect software, do you know how to increase the x axis MeV range? I seem to be stuck at somewhere between 1.5 MeV and 2.0 MeV, maximum resolution. I would like to expand it so I can display information out to about 3.0 MeV, but no matter what I try once I get a good spectrum, for example Co-60, the spectrum looks great but I can't see anything above about 1550 KeV, that is the right side of the graph stops at 1550 Kev. I've tried adjusting the coarse gain but 2.0 is as low as it goes and that value gives me the greatest x axis resolution. I'm probably doing something stupid but I just can't figure it out. Any suggestions would be appreciated.

Bob,
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pietkuip
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Re: ProSpect (Canberra) quick guide

Post by pietkuip » 01 Oct 2015, 22:03

The real range can be changed by changing the high voltage of the photomultiplier tube, so you should probably decrease that.

The numbers on the horizontal scale depend on the calibration. It starts with a default scaling of 1 keV per channel. One can change that when one knows what peak is at what energy.
Pieter Kuiper, Växjö (Sweden)
Course lab: 3 mCi neutron source; five 3" NaI(Tl) detectors, CdZnTe detector (Amptek); lead bricks, two GDM 20

rodorr
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Re: ProSpect (Canberra) quick guide

Post by rodorr » 02 Oct 2015, 01:42

Pieter,

Hopefully this question isn't too stupid but I want to make sure I understand this properly. If I choose the default calibration and I choose 1024 channels with a coarse gain of 2 and a fine gain of 1, I should get a displayed graph with a horizontal range of 0 to 512 KeV. The way that I understand it is the displayed horizontal resolution (energy) is defined as the, number of channels, divided by the (coarse gain, times the, fine gain). So if I choose 1024 channels, coarse gain of 2, and a fine gain of 1, I get 1024/(2*1)=512. If i chose 2048 channels I would get 2048/(2*1)=1024. Is this the way it is supposed to be calculated? If not would you let me know what the proper formula would be.

Thank you very much for any assistance you can give.

Bob
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pietkuip
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Re: ProSpect (Canberra) quick guide

Post by pietkuip » 02 Oct 2015, 05:38

I do not think I have used the course of fine gain setting on the Osprey. I am not quite sure what it does, might be a setting of an analog amplifier, might be a digital thing in software. They also talk about "conversion gain", which I understand as the number as channels.

I am not sure if I understood your problem. If you want to look for gamma lines beyond the highest channel, you need to reduce the pulse height. I am not sure if "gain" can to that. The best way to reduce the pulse height is by reducing the amplification already in the photomultiplier tube. In the Osprey, this is under computer control in the ProSpect program. Just reduce it in steps of 50 or 100 volt and you should see that peaks move to lower channel numbers when you restart data acquisition.

I agree that the program is not as intuitive etcetera as is advertised. And that manual... it lacks a basic quick-start guide. But this was sometimes helpful: http://www.canberra.com/products/resear ... C40691.pdf

Maybe I can answer better tomorrow at work, where I can check the setup.
Pieter Kuiper, Växjö (Sweden)
Course lab: 3 mCi neutron source; five 3" NaI(Tl) detectors, CdZnTe detector (Amptek); lead bricks, two GDM 20

rodorr
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Re: ProSpect (Canberra) quick guide

Post by rodorr » 02 Oct 2015, 10:55

Pieter,

I think I have it figured out but it wasn't what I was originally thinking. The only real way to control the horizontal (energy) is by varying the high voltage to the probe. I had to drop the voltage down quite a bit to get the range I wanted but it worked. Thanks for your assistance.

Bob
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