Gamma Spectrometry Forum

I'm new to this. Please let me know if I violate any rules or conventions whether written or unwritten.

I'm trying to activate some Thai Gold foil with an Amstat NucleSpot Static Eliminator plus Beryllium sheet Neutron source. In addition to the NucleSpot, I have an Americium 241 smoke detector mast from a PyroTronics F3/5A with a Beryllium ring there. The third neutron source is a Radium 'backlight' from a Russian DP-63A covered with a Beryllium sheet.

I get about 75-110 neutrons per second on an ESP32 Arduino board with my code on it when measured with one of Steven's Schmitt-Triggers connected to an SI19N in my polyethylene castle.

I left the gold foil on top of the NucleSpot assembly. The other two sources were bunched up closely. This was all inside of my poly castle for 100 hours.

The gold foil showed 65 -75 CPM on my GMC 660+ before it was irradiated and about 85 - 120 afterwards. I did a spectrum with one of Steven's GS-2020 NAI tubes and got this 24 hour Pulse-Height Histogram:



Did I activate the Gold foil?

Mike D.

My poly castle is a giant pile of polyethylene blocks:
viewtopic.php?f=10&t=1087

My lead castle:
viewtopic.php?f=10&t=1086

Mike,

Hard to say with certainty. it looks as if your calibration may be a little bit out, but you seem to be getting a peak in around the right area.

Maybe if running the histogram for less time will give a clearer result... not sure.

This might be a case for trying the Impulse 3D spectrum ???

In PRA you can try isolating the 411 peak and look at net counts during 1 hour intervals, and if it agrees with a 2.7 day half life you can be pretty confident of success.

This is easy to do just using the data acquisition and analysis panel, it won't change anything in the recording.

Steven

Mike,

Forgot to mention you may need the advanced filter to select the ROI or you could simply select the ROI with your b and e keys (highlight yellow).

Either way you will get the net counts.

Steven

I'm not sure that I understand. I really do appreciate the helpful diagrams. Is what you are describing by the hour or by the half-life of the gold? I can use the run numbers I already have saved as .pls? I tried the ROI by using 'B' and 'E' around the 411 peak area. Then I changed the setting to 0 and 3600, 3600 and 7200, 7200 and 10800, and 10800 and 14400 seconds. It seemed to be going up in the counts for 411.591.

I only ran the spectrum on the 'activated' gold foil for one day after activating it with neutrons for 100 hours. The foil got more active in terms of CPM afterwards. Doesn't that count?

I am starting a new attempt. I have only a vague understanding of what the PRA SW's different views represent. I will learn and am trying very hard and I am earnestly trying to ask intelligent questions.

This time I am measuring the CPM before and after, and doing a spectrum of the gold leaf before activating it as well as after. I have a 24 hour background that I think I'm subtracting from the displays by clicking the Use Background button on the Data Aquisition page and loading the run I saved as being a background and set data as background button.

I am doing a new gold foil as I type.

Thanks,
Mike Driscoll

Mike,

My suggestion was to analyse the last recording you already ran.

All you need to do is use the advanced filter and the Data acquisition and analysis to slice up the recording in 60 minute intervals and put the counts in the ROI into a spreadsheet.

If the resulting data plots an exponential decay, you can be confident of a positive result.

Steven