We are live tweeting a fusion attempt today. Olivia Koski, a science journalist student is here to document.
Summary:
2 hours of bakeout prior to metered trial.
Calibration on the bubble detector label: BD-PND, 25 b/mrem(2.3 b/uSv).
Bubble detector is 95mm from the center of the grid.
We got a single bubble during an 8 minute run:
Towards the end of the experiment we noticed a wild outburst of geiger activity while the fusor was _not running_. Not sure what this means. We got it on video:
Using twitter as an experiment log worked very well. It helps capture details you notice along the way with timestamps.
Prometheus Fusion Perfection 
radiation bursts? neutron activation? duh, you really need to get rid of stuff made of material that becomes activated easily. radiation is a bitch, huh?
Would geiger activity from activation greatly exceed the activity from actually running the fusor?
most probably. the faster the element decays the more energy it will deliver. most probably in the form of a shorter wavelength, which means it gets more ionizing. or, alternatively charged particles. alpha/beta radiation.
be serious about neutron activation!
That is amazing.
good analogy: if you empty a bucket quickly, you’ll get more water. and of course, the bucket will be empty faster.
Chris Bradley says:
Very doubtful you will get detectable activation if you’re showing just a single neutron bubble. Not sure that really adds up. Steven Sesselman got similar results when he first cranked up his novel design; a continuation of readings after the run. I don’t recall what that was put down to, but I don’t thing the numbers supported any prospect of activation, and he had more than one bubble!
http://www.fusor.net/board/view.php?bn=fusor_construction&key=1258998413
uh, while it was not running? of course, that makes EMI quite probable. best thing i guess would be to get fancy geiger graphs. there aint such a thing as too much data (at this point)
of course, some shielding on the cables and the geiger counter might improve the quality of the data too
last but not least: you might want to check labVIEW, very popular among the experimental physicists here. or, as an open source alternative, SciLAB. better than fiddling with google graphs, and you get it real time ;)
Can you use SciLAB as an interface to the NI USB 6008?
dunno if you can do it out of the box, but if it feeds data, you can probably easily make it eat
I still think the first step should be to check the Geiger counter to understand its limitations (if any).
Was your HV supply still running? Seems more likely that whatever RFI problem is crashing your DAQ is also ionizing the gas in the Geiger tube. Geiger counters are pretty twitchy.
you might want to plot the geiger counter readings to determine a real half-life that isnt as mumbo jumbo subjective (no offense) as approximating.
plus, if the curve doesnt show an exponential fall-off it might be something else. (or something in the air becoming activated and carried away)
I think I can hook it up to the counter channel on the DAQ. Might be a good next project.
you might also want to remember the level at which your geiger counter started. in case slowly accumulating activation radiation sneaks in through the back door, slowly
when i think about it, sweepin everything with the counter just to make sure might be a smart thing too. better to be paranoid.
Can you pass me the model specs about the geiger counter?
I have the doubt that what you have might not be a true geiger counter in the strict meaning of the term.
Also I am interested to know if it is able to differentiate between alpha, beta, gamma and x-Ray radiations.
http://www.blackcatsystems.com/GM/cdv.html
Giorgio.
Details for the geiger counter:
eberline geiger counter
model e-520
serial 4787
What is the probe model?
The probe is:
model: HP-260
serial: RN015638
IIRC Tom Ligon mentioned something similar in a pre WB-6 model.
Famulus…
Incredible work you are doing!
I just wanted to say that geiger counter going off like that make me nervous. Take a lot of care with the potential for X-ray exposure. Maybe you should get another counter or two and keep them with you in the ‘safe’ area you are running the experiment from. That way you can be sure that your body is not getting exposed, even when the one pointing into the fusor is clicking.
Makes me nervous too!
I have a new USB geiger counter coming on friday for comparison.
Who knows, may be something unrelated to the experiment.
New hypothesis on those geiger outbursts:
It’s the vacuum pump!
This afternoon I’m listening to the geiger count background with the system off.
When I turn on the vacuum pump I begin to get outbursts form the geiger counter.
I don’t have numbers for this yet, but I can hear it for sure.
hm. maybe its the generated radioactive tritium getting pumped out of the vacuum chamber?
it’s really hard to tell. m-m-m-m-ore daaaataaa
Interesting. I used to work in a semiconductor lab and we took measurements of sputter and electron beam deposition of metals using x-rays through a sample that went in with the wafers. We had radiation dosimeter name tags that were checked monthly for those of us that used the x-ray room. We had a few Geiger counters in the room. One of them was flaky and it occasionally would give off a burst of static sometimes which was never really a radiation leak. There were vacuum pumps all around too, like in the Balzers. I wonder if they can be set off be EMI? Or even directly the little speaker on them. Maybe your pump is emitting lots of noisy radio waves.
“I wonder if they can be set off be EMI?”
Absolutely. Ever see someone light up a fluorescent tube by holding it near a ham radio transmitter, Tesla coil or VDG generator? The Geiger tube is literally designed to exploit that effect.
I powered up an X-ray tube with a Glassman supply awhile back and found that my Radalert counter would trigger just from the electrostatic field from the HV supply by itself.
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