Our last fusion run produced results we can use to calculate the neutrons per second emanating from the fusor.
To help with converting from bubbles to neutrons per second I contacted Rob Noulty of Bubble Technology Industries – makers of the bubble dosemeter we are using. He says:
Hi Mark:Did you run a control detector (to see what natural background bubbles you will get over this time)? You must subtract these bubbles out assuming you have two detectors of roughly the same response (or you will need to scale).Please note as well that you have a very small number of bubbles resulting in poor statistics (and a very large error). Based on 4 bubbles, the expected error is roughly 50%.The calculation is follows:1. Divide bubbles by the sens in b/mrem2. This will give you the measured dose in mrem3. Divide by 3.48 x 10-5 mrem /(n/cm2)4. This will give you fluence (in n/cm2)
My detector has calibration: 24 b/mrem (2.2 b/uSv):
Here are my calculations:
- 4 bubbles in 2 hours and 40 minutes
- 4 bubbles/(24 bubbles/mrem) = 1/6 mrem
- 3.48 x 10^-5 mrem = 1 n/cm2
- 1 mrem = 28,735.6 n/cm2
- 1/6 mrem = 4789.27 n/cm2
- Surface area of a sphere 7.62 cm radius is 730 cm^2 .
- 4789.27 n/cm^2 * 730 cm^2 = 3.49617 * 10^6 neutrons in 2 hours and 40 minutes.
- 2 hours and 40 minutes = 9600 seconds.
- ( 3.49617 * 10^6 neutrons)/9600 seconds =
- 364.2 neutrons / second.
- The neutrons represent half of the total fusion reactions happening, so multiply by two:
- 728.4 fusion events / second.
This seems to ballpark agree with this fusion calculator:
Question to the community: where do I apply the error factor?
Also, I have yet to factor out the background reading I did previously: 1 bubble in 3486 minutes (2 days 10 hours 6 minutes).
Rob Notes:
There are two conversions, depending on dose conversion table to want use!
USA is going to ICRP-74 slowly, we use NCRP-38.
NCRP-38: 3.48 x 10-5 mrem/n.cm-2
ICRP-74: 4.16 x 10-5 mrem/n.cm-2
Prometheus Fusion Perfection 
