2" Hornyak build details

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2" Hornyak build details

Postby Doug Coulter » Sun Jul 17, 2016 4:57 pm

I'm building a new Hornyak detector for fast neutrons as we noticed some asymmetry in the fusor output (again) and wanted to chase it down a bit with a fairly localized detector - ignoring slow neutrons which are everywhere when a fusor is running. Hornyaks work by letting fast (only) neutrons knock a proton out of some plastic, then letting it energize some phosphor that's more sensitive to charged particles than it is to other things like gamma rays. That would in this case be ZnS:Ag.
It's not a lot of light per neutron, and we want to see them individually, so about the easiest way is to use a Hornyak button on a photomultiplier tube. This means all manner of construction issues to get it light-tight, build the dynode divider chain (this post), shield it from external noises (it's not usually a huge signal) and leakage, and so on.

Turns out that what is philosophically trivial isn't all that actually easy unless you know a few tricks, I thought I'd put a few here.

The writer of one of my Perl books said (sorry, I forget which one but a shout-out to y'all in the community) - that he dies a little inside every time he sees someone mindlessly doing the same 4-5 key stroke over and over again to say, reformat some text. Gee, you're on a computer, it runs programs, the entire point is to automate things like that! There's an analogy in shop work, called a jig (don't gag Jerry, not everyone here is as good as you are at this kind of thing).

I want this detector working more or less yesterday, and I didn't have the just right resistor values in stock (and resistors are so cheap I'd have to figure out a few other things I want to make anything like a minimum order at my chosen vendor). But I had a big bag of ones just half the size I wanted. Soooo...I need a bunch of these, hooked in series in pairs. Yes, I can do this by hand, I'm fairly dextrous for a left handed guy, but...I'm in a shop, it's full of tools that can make tools, darnit - same as being on a computer that has say, perl on it. Soooo...we build a jig for this, since it saves more time than it takes to make, and saves lots of fiddly frustration. Like so:
ResistorJig.JPG
Simple...

I just needed a slot and a couple small flat weights. Not shown is the other side, where I tried different slot depths - it's easy on a table saw, and by cutting a few, I knew I wouldn't have to walk back across the shop. So you cut your resistor leads, put them in the slot, and set the weights on them like so, and solder:
InUse.JPG
Just solder this - the weights prevent the surface tension of the solder from lifting it all off the bench.

And almost before you know it, you're done:
Finished.JPG
All those pairs that are all nicely uniform done in a jiffy.


Bonus - as I mentioned in the linked thread, I also made a jig to make the lead cap for the end of the tube, and that the other end hand nice markings on it from my sloppy saw work. I also added that next bit of copper tape and wired all that to the cathode, so that there'd be zero volts across the maybe-leaky glass/cathode interface (this has bitten me in the past) :
100_3088.JPG
Bonus shot
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: 2" Hornyak build details

Postby Doug Coulter » Tue Jul 19, 2016 5:05 pm

This is ~ $100 of "worth every penny": https://www.amazon.com/Copper-Conductiv ... opper+tape

Which lets you do things like this:
100_3090.JPG
Shielded PVC pipe using copper tape, overlapped and soldered in-place..


I use this all over, including say, inside an electric guitar to kill hum, to be a "shorted turn" in RF situations, you name it. Solderable without messing up the adhesive. Now I have a pipe that's insulating on the inside, yet grounded and shielded outside.

I built up more more or less standard HV supply for this, schematic to come. It's just a 12 watt (big) 12 volt 1kv output CCFL inverter, a couple fast diodes in a voltage doubler, some output filtering, and an lm150 input regulator. Fairly "stiff" output so it doesn't really need feedback regulation, particularly with this fixed load.
100_3089.JPG
Power supply and other parts


I'm using a 9v 800ma wall wart - because it was laying around (same reason I used an lm150 instead of a lm317). It puts out around 11.7 volts under this load (~ 2 megs across the HV output) at full crank which is around 1900 volts out - more than I need here most likely (shooting for around 1200 or so, which I guess is about right). These older transformer wall warts put out much higher voltage at light loads than the spec, just about universally. This is due to them using cheap, thin wire for the windings, so to meet spec at full load, they have to account for a lot of series R in the transformer itself. Saves a little heat in the series regulator under load, too. Just a tip - right-sizing is good design now and then.

This will be mounted on that aluminum angle bracket with the copper end plate (which will shield the phototube from the noisy CCFL). Any other electronics will go on the other side of the Al plate to avoid that CCFL noise, which is prodigious - 1kv of fast risetime 50khz is no joke. That little piece of copper flashing (also an expensive but worth it kludge material) will be punched out, retained under the BNC nut, and hold the other end of the Al plate. Thus, the power supply and any preamp or audio provision will be able to just slide out of the end of the pipe.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: 2" Hornyak build details

Postby Doug Coulter » Fri Jul 29, 2016 12:59 pm

A little more progress, kind of interrupted by Dr's office visits (grrr) but those who won't be stopped....
Here's the enclosure. I ran the cap through the die again with the pipe as the pusher to get it as close to light-tight as possible, then glued it on with black silicone (not on every street corner, but from McMaster-Carr).
100_3092.JPG
Pipe and cap
I will solder a wire to the cap and to the copper tape to ensure it's well grounded.

Now I'm working on the other stuff - next to the power supply mockup is another phototube without the hornyak button, just for looks (it's not wired correctly for this application anyway).
100_3093.JPG
Partial mockup of power supply and other end cap
Notice the aluminum bracket roughly centered in the enclosure that will hopefully keep its noise away from the other side of it, where the signal will be. I will of course use coax for that. The copper flashing ring on the table end is also to help with noise, and probably a little with light leaks. Mostly noise. I cut a piece of teflon sheet to go right behind th phototube and prevent shorts, and will fish around for some super-black foam rubber I have from another photodetector somewhere to push the phototube to the front. Inside the front of the pipe I glued in a couple of 3/16" spacers so the -1000v or so copper wrapped around the phototube and detector won't short.

Here's a little more finished looking power supply and back end. Yes, I actually got the calculations right and the pot is centered when it's putting out what I think is going to be the right voltage. Incoming power uses the old "tie a knot at the hole" strain relief, and more black goop.
100_3094.JPG
more complete back end

My goal for today is to get this wired the rest of the way up, and into total darkness.
This is the part of this that stinks the most - you have to trust you more or less got everything right, and exposure to light "charges up" the phosphorescence of the ZnS, so you have to wait 24 or more hours after each light exposure to test the thing. For someone with my (lack of) patience, it can be excruciating.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: 2" Hornyak build details

Postby Doug Coulter » Sat Aug 13, 2016 12:24 pm

And....it stinks. Turns out that phototube, (ebay) was bad, couldn't get a signal past PCB leakage out of it no matter what.
So, we bought a new in box tube and a new hornyak button from Eljen. The sad thing is the new tube has a base on it that won't fit in the plastic pipe, so I get to do nearly all of this over.
I stupidly used optical epoxy to glue the old hornyak button to the bad tube...since grease would have ruined the stickem on the copper tape, and it's not a place you want to solder while on the glass...

More when I have more. I have to use a larger pipe to clear the base for the new tube, which means a new piece for the back end too and various other fiddly junk. I'll get there.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: 2" Hornyak build details

Postby Doug Coulter » Thu Aug 25, 2016 5:21 pm

I have a little bit more on this. This one has had to take a slight back seat due to a patent final-filing deadline, and the data I expect to collect with this isn't relevant to that directly.
So, the new tube wouldn't fit in the old pipe. Obvious solution - get a bigger pipe. We did, it's stainless steel, and a new set of caps had to be made for it, a socket for the tube wired up and so on, those parts are now done:
100_3107.JPG
Getting there


The old power supply will fit, I have to drill the back end cap for DC input and BNC output, and make a new round holder, emi shield, and light-stop for the far end of the supply.
I will probably just make a little thingie with a 9v battery, a tiny speaker and a couple transistors to be a clicker I can just hang on the BNC for hand-held use.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: 2" Hornyak build details

Postby Paul Fontana » Thu Sep 01, 2016 1:07 am

Hey, Doug,

Can't wait until the Big Reveal! Sounds like it's coming up soon. Even better, sounds like you're getting close to having your remote system online and will soon know if what happened before is reproducible. I'm excited to find out - I'm sure many others are as well.

This thread and other recent posts give the impression you've been getting some sort of data recently. You haven't come back up and not told us, have you?
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Re: 2" Hornyak build details

Postby Bob Reite » Sat Sep 03, 2016 10:42 pm

Judging from Doug's most recent posts, he's finishing up the remote control system and the patent process is progressing. I'm guessing that he might have some data for us a couple of months from now.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Re: 2" Hornyak build details

Postby Doug Coulter » Sat Sep 03, 2016 10:59 pm

"Real soon now" is the hope. I just almost finished the remote system (rev 1.0) today, so we can soon run in what we all hope is the replication of the gonzo mode. Only two months late after I promised Motherboard I'd be ready for journos again. Sigh. Hope they have a long enough attention span. They tried to be pretty accurate within their agenda last time, harder than any other journos have here. They have to put more emphasis on popularity than "eyes glaze over" detail, of course - but who better to spread things widely in the court of public opinion? Which is as necessary as hardball lawyering on something potentially this big.

This particular detector build (temporarily shelved) was because of something we noticed in "old" mode - a ring of very many hot 84 keV gammas coming out of the front of the fusor, through lead that should have stopped that cold (it's the K line of lead according to a gamma spectrometer, FYI). But time is of the essence in our final patent filing, so I set this aside for the moment to finish the software/hardware lashup for remote operation. My guess was it was excited by a flood of neutrons there...in addition to the ones in the back where we activate the silver and measure the flux. This was FAR louder.

The remote is now working in the "hothouse" mode - eg on the bench not hooked up to fusor sensors. I have only a few more lines of code to do to make it control the gas and ion stuff remotely (easily and from within the master program, it already works from things like the arduino IDE) - probably finish tomorrow. Then we move all this from my bench to the fusor, hook it up, and start troubleshooting (there's a lot of plain old cabling and connector wiring to verify if nothing else), still in "old but safe" mode. Hopefully that won't take too long, but you know how it is with Murphy. We expect to be at least trying it in the next week. We'll know when we know.

FWIW, we are talking about 10 channels of a/d (with appropriate input conditioning for each channel), 3 fast counters, 3 high rez video cameras, stereo audio (all streamed back in realtime, audio with zero latency) and a couple channels of "control this gas solenoid and ion source" going back the other direction. (Three raspberry pis, two arduinos, not counting the master machine over here) The numeric stuff is all at 10hz and time stamped. If I could implement smell-o-vision and a few other things I would. Don't know how. All this going into a near-real-time remotely replicated mySQL database...just in case.

And oh yes, some absolutely "safety engineered" hardwired telco burial cable to for certain be able to shut it down no matter what else crashes. Every failure mode we could imagine is to "off".
(We includes partner Bill Fain who doesn't take enough credit for all this, but it wouldn't happen without him and his "dumb questions" and endless support. And also, John Futter, who kind of noticed a couple things himself when he visited and put me on the right track on some measurments.) One near death exposure was more than enough for me. I put some serious skull sweat into fail safes this time.

Once that flies...we go into the other mode (which is a lot more radiation and also EMI) - and troubleshoot that, which is a fairly unknown issue = hard to predict what we run into. A small-geometry but well (emi/gamma) shielded intel NUC crashed in milliseconds last time it happened - else I would have my data and already be done. I deliberately used "disposable" parts for all this so if some get fried or just die from transmutation (yup, if it works again, we're at that level), they're easily replaced (all the code etc is extensively backed up and the backups tested). And these parts are a lot harder to harm than an X86 - bigger geometry transistors and memory cells, takes more junk to flip a bit in this stuff. Arm and Atmel - and redundant. I was hoping to skip that level of effort before, but we got unexpectedly successful, or as Bill said "got to a bad good place to be". I kind of expected another 3x or so for each new insight, not 10^8 or 9 kinds of improvements!

So yeah, we got a little extra data running a demo for someone in "old safe" mode that led to wanting this detector to chase it down, as it seems like only neutrons emitted far from where we *thought* the main action is are generating it - and we may have been putting out a few tens of times more fusion than we thought...which is of course really interesting all by itself. If my guesses - and that's what they are - of what we had in the gonzo mode are right, it means we're above unity in that mode, assuming we replicate. Pretty exciting stuff! We thought we had a last 10x or so to go, but maybe not. Definitely some interesting science yet to be learned here. Actually, the most gratifying information other than that was that after 18 months just sitting, it all came right back up and flew just as before. It's stable! (it did sit under high vacuum that entire time) That would seem to make replication require less of a fluke.

I'm also aware of, and in agreement with the old saw "extraordinary claims require extraordinary proof" so that's the track we are on - getting that proof, to at least a couple decimals and all the whys and wherefores. Or not. Whichever way, we report on it. I'm pretty sure it works, as I did spend those 7 or so weeks puking (and worse) from overexposure and I think I have a pretty decent "existence proof".

What I'm doing now is to get just a few more data points on the replication so we can do the final patent filing on time and then I can shout it from the housetops and give it away - the sad truth is we have to pay and do extra work to own the work we did already over the last decade and ~ $500k (not counting labor), but it is what it is. If we don't, some jerk could take our work and charge YOU for using it. We are still dedicated to just plain giving it away (though we'll accept consulting fees of course if you want a bunch of help making one). But you can't give away what you don't own.

Sadly, some medical issues set me back a couple months, but all is back on track now. So expect some news pretty soon. I can't really get into certain details till the legal beagles tell me it's ok, but that won't be long one way or the other - there's a time limit (October). Along with the bad part of "patent reform" - eg first to file vs first to invent - is now a limit on time - no submarine patents are allowed anymore.
This is a good thing, but it's got me in a time-crunch. I've really only been posting here lately to let people know I'm alive, OK, and still going at it.

What is philosophically interesting (or at least one of the things) is the realization that nearly all our breakthroughs - and there have been a few - have come due not so much to analyzing the data acq, but to some human (often me) noticing that old cliche - "hmm, that's odd" - and then taking action based on that observation of something no one thought of hooking up to data acq. So, faced with (forced to) go remote - How the heck do I put a "me" robot over there at the reactor? How do I set up to observe the unexpected? "Be prepared" is a good motto for boy scouts, expect the unexpected is a rule - but which unexpected? By definition, impossible. I'm sure that despite the best I can do on rev 1.0 - there will be more we wind up having to do. As we used to say in the software biz - rev 2 is the first one that works right. It's not that the data acq has been worthless, far from it. I think we can now explain some of Farnsworth's "anomalous results" that he couldn't replicate - and why. We just have much better stuff to know what's going on and can do on purpose what seems to have partially already happened by accident. And then tune it even better.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: 2" Hornyak build details

Postby Doug Coulter » Sat Sep 03, 2016 11:26 pm

O/T but here's what the remote pi screen looks like here at the op position (leaving out the web streamed cameras etc) at this point. I'm using tightVNC for that.
PiRemote.png
Just finishing this up.


See link:

Any further news on this will go here for now.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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