Neutron detection moderator embedded activation!

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Richard Hull
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Re: Neutron detection moderator embedded activation!

Post by Richard Hull »

I have scoped the tube during my assembly as I adjusted the proper GM tube voltage. An immaculate scope trace resulted no noise, a flat, zero volt base line save for the huge 5 volt detect pulse sent to the Arduino interrupt pin. Finally, the tube has zero tungsten in it. The shell is pure, very thin aluminum to let in the betas to which it is most sensitive along with very low energy gammas. High energy gammas arriving at the tube would zip right through undetected. An Am241 source makes it scream as those are only 60 keV gammas and are easily detected due to photo electrons from the Aluminum shell. So, there is zero noise in the electronics and zero tungsten present in the tube. This is why I refuse to even take a count with any fusor power applied or the supply even turned on at zero variac position. I have a total power kill switch to the HV control variac before I press the count begin button. The entire area is EMF free during the count.

Richard Hull
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Re: Neutron detection moderator embedded activation!

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Still battling the background. Lots of suggestion from Bill Kolb as well as Frank. I just can't kill background even with 5/8 thick lead plate due to gamma P.E. and Compton radiation.

Due to dispersed storage issues, I have gamma coming in at this setup over a 2 pi situation and just can't shield the moderator over that range. I can only shield for my most intense direction gamma. Add to this the Compton scattering and Photo electrons from the GM tube walls, it is just not merely a case of a whole bunch of lead unless I could attempt to shield over that 2 pi range. My current setup will not really allow that, so I hit the hot directed gamma with shielding and it is what it is.

Enjoy, mumble, muse and cogitate. I think I will just go with the 1/16th inch sheeting and carry on. I was rather unimpressed with the external 5/8 thick lead. It covered only about .4 pi from the most intense direction. It is that uncovered 1.6 pi that made the 5/8 inch thick reduction unimpressive

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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Re: Neutron detection moderator embedded activation!

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To beat the background back a bit in the resultant Ag activation effort, I will increase the surface area of activation by 800%! See image below.
The beauty of the variable and movable components of the "toy block" built up moderator is showing its value. I have already tested the tube in its assembly for background in the moderator. It is just a tiny bit lower on average than the old setup. The old setup will be kept in reserve of course.

I will cover the new rectangular form in the next day of two and test it out. I will keep all abreast of how it does.

Richard Hull
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Large GM Anno.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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Re: Neutron detection moderator embedded activation!

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Another great activation this evening. I was able to hit 3He numbers of 93,000 cpm for about 3 minutes after 6 or 7 minutes at rates over 40,000 cpm on the climb past 60,000 and 70,000 to 80,000. I find that skipping just one day of operation the system is difficult to push above 60,000 cpm. However after two days of rest, I have to run the system and struggle to get to 50,000 counts, however if I shut down and let the fusor chamber cool and start back up 3 hours later, I have no problem hitting 80,000. I dare not experiment and leave the system off for 2 weeks. I will prep the system prior to the big HEAS event in early October as folks will expect it to function well.

I attach the graph of the Excell file.
Attachments
Hit 110 counts in the first 10 sec count! (660 cpm)  I can start the count within 2 seconds of the shutdown of fusor power.
Hit 110 counts in the first 10 sec count! (660 cpm) I can start the count within 2 seconds of the shutdown of fusor power.
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Fusion is the energy of the future....and it always will be
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Re: Neutron detection moderator embedded activation!

Post by ChristofferBraestrup »

Very intersting progress! There is one problem that have been nagging me ever since you made this thread: The STS-5/SBM-20 tubes are aluminium-cased, they will undoubtedly activate as well. For aluminium activation this might be of no consequence but for silver, shouldn't the corresponding decay be two superimposed decay functions? And given the aluminium casing, couldn't the tube by itself function as a complete assembly for Al-activation?

I think it would be interesting to try out a similar concept with a flat-plate plastic scintillator coupled to a PMT with a long-ish acryllic light pipe.
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Re: Neutron detection moderator embedded activation!

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A non-issue for sure. Aluminum requires a lot of neuts delivered over a much longer period to activate to any measurable degree compared to Silver. Fusors are operated over rather short periods. As such, the aluminum has no figure in this case. How could the tube of the GM boost the silver activation?? It will not emit neutrons as it is activated. The silver would absorb most of the thermal neutrons that try to reach the aluminum due to the cross sectional figures. In short, the silver would act as a neutron absorber, protecting the aluminum to a degree from activation.

Of note, there are indeed two simultaneous decays going on with Silver! There are two that can fully activate rather for any given flux within 600 seconds of exposure. This is why I chose to set the Arduino up to collect data for only 600 seconds. (see graph)

Ag110 will fully activate from activation time, t=0 and be in "activation equilibrium" in 130 seconds! Ag108 will fully activate to activation equilibrium from T=0 within ~600 seconds. The instant neutrons go away, (fusor turned off), both nuclides start to decay from decay time, T=0. Thus a complex curve results plotted by solving simultaneous, dual exponential decay equations. My friend Bill Kolb has joined me in this effort and I submit his efforts on my behalf in the image below.

Aluminum has no place in any of this unless one has access to a steady 10e5 neutron flux over the normal 600 second activation period as Al27 has an atrocious cross section of 0.2 compared to either of the silver nuclides, the worst of which is 150 times more likely to capture a neutron than the aluminum shell of the GM counter! Add to this, the fact that full activation of the aluminum would require an exposure time in any flux of 10,100 seconds 17 times longer than I expose the silver for....Figuring further.... at my peak first 10 second count, (see graph), I detect 10 bq of total silver activation radiation. The aluminum by comparison would contribute but .0006 bq to that count over the 600 second neutron activation period. I now consider Bill Kolb as a partner in this endeavor. As such, the graph is 100% attributable to my old pal,William Kolb.

Richard Hull
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Bill Kolbs best fit 8-16 and 8-30 activation.JPG
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Re: Neutron detection moderator embedded activation!

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I have, since HEAS, been busy with my activation efforts following a degree of calibration for my system due to Bob Reite bringing his remball system to HEAS. (my remball system has a defective indicator electronics box). Many of the preceding images in this post have been made with my Arduino data logging box. This box took 60 successive reading of 10 second counts. This comma delimited data was placed in Xcel to generate all the graphs seen in all the preceding posts. Bill Kolb has assisted with his work on generating a computed best fit for the dual silver decay paths which agree very well with the data collected in the graphs.

As the silver 110 decays with a half life of only ~24 seconds, the first ten second count is a smear of counts taken over almost a quarter of the half life, I have changed two values in only two lines of code in the Arduino program to alter the count interval to only 5 seconds taken over 120 counts. (Still a 10 minute data collection period.). It is realized that statistically halving of the count, doubles the error. However, I feel that the long 10 second count will smear, by a large amount, the first half-life's peak of Ag108. It is unfortunate that the background is so high, yet, also halved along with the total interval's count. It is hoped that the peak of the AG110 will be more representative of the first 10 count intervals.

Note: If this shorter interval of 5 seconds proves too noisy I will return to the 10 sec count interval. This may be the case once I get the Rhodium.

I submit my new background graph over the total 10 minute count interval. I also contribute the decay graph of a super run of fusor five with a peak TIER of 825,000 n/s run with a peak neutron count in my detector of 140,000 CPS.

Richard Hull
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NeutACT 11-4-20.JPG
Background 11-1-20 5 sec.JPG
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Neutron detection moderator embedded activation!

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To go with the above post, Bill Kolbs best fit for the Ag110 and Ag108. The run on the 4th was really great.
While the scatter is amplified due to the 5 second counts, the trend line clustering is obvious.

Richard Hull
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Bill Kolbs best fit 11-4-20 activation.JPG
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Neutron detection moderator embedded activation!

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There be Rhodium!

Yes, I bit the bullet, spent the long buck and the image is contained below. It cost exactly what I recently paid for the large 6" - 6 way conflat cross!!
I hope to set this up in my enclosed moderator activation scheme in some fashion soon. More later. Yes, the sting of $500 still hurts a bit, but the die is cast.

Edit 11/20: What a difference a day or two makes! Rhodium hit $13,800 per troy ounce!
Edit #2 11/23: Rh hit $15,300 today for a while.

Richard Hull
Attachments
Rhodium.anno.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Neutron detection moderator embedded activation!

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I finally ran the rhodium activation effort. I attach images of the probe modification and of a 20 minute comparison, activation run of silver versus rhodium.

A bit of background. I have not done any activation since a week of two after HEAS. As some may remember I did fantastic activation at HEAS with over 120,000 peak CPM neutrons in an activation run. Laying fallow for two months, the wall loading was zero. I spent about three days of running fusor V to just get the fusor back up into the 80k CPM range, at best! I have shortened the count to 5 seconds per data point in the Xcel graphs, to better capture the fast decays. Nonetheless, with fusor V producing less than optimum results and the lab getting colder, I decided to try the effort of comparison runs.

As some know, the Ag 110 has a half-life of 24 seconds and decays very rapidly. It has a neutron capture cross section of ~80. Rhodium has almost double the half-life with a cross section of ~145 These two characteristics make it the ideal fast activation metal with the highest cross section of its one isotope composing 100% of the metal. Silver 109, the fast activator to Ag 110 is only 50% of the metal. Rhodium is king, for sure.

I went into these runs worried that rhodium due to a number of factors would be crippled due to the factors listed below.

1. The old silver probe is seen to have 100% coverage of the activated metal as a nice cylinder of silver of 9999 purity completely covers the GM tube. The rhodium covers only two sides not even 50% coverage.
2. The old silver probe had 100% of it active detection length exposed to the activated metal. The rhodium strips do not cover the entire active detection length of the GM tube.
3. Worse still, was the fact that the silver run on the 24th had a fusor conditioned over its 3 day prior runs so that on the 24th, ~90,000 CPM neutron counts were obtained. I skipped the 25th not running the fusor at all and in just the 36 hours lost, the Rhodium run struggled to hit 74,000 CPM ( slight loss of wall loading.)

YET! The rhodium run beat the results of the silver run in spite of all the above handicaps! I love the longer single isotope decay time that spreads the decay out over time.

Net Results

Rhodium obtained 22% more activation with only 81% of the peak neutron activation that silver had and with only 45% of the tube counting versus 100% of the tube counting the silver....Wow!

Check out the photos and graphs. Rhodium is the the cat's pajamas!

Richard Hull
Attachments
Rhodium 1.jpg
Rhodium 2.jpg
Rhodium 3.jpg
Silver, silver, silver above  for comparison as noted in the above test.
Silver, silver, silver above for comparison as noted in the above test.
Rhodium, Rhodium  "Less is more with rhodium"  speaking in the Orwellian
Rhodium, Rhodium "Less is more with rhodium" speaking in the Orwellian
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Neutron detection moderator embedded activation!

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Excellent results Richard. Now you have me wondering if there’s an inexpensive and easily obtainable rhodium alloy that could be used for activation.

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Last edited by Mark Rowley on Fri Nov 27, 2020 3:12 pm, edited 2 times in total.
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Re: Neutron detection moderator embedded activation!

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Rhodium plating was often used in the past on cheap junk jewelry as it provided a had and bright overcoat that would not leave a green of colored remnant on the wearer's skin. Rhodium was often sold in solution by atomic weight for plating. Needless to say any rhodium alloy or chemical compound would be priced based on the market spot of the current $14,700 per troy ounce by its atomic percent weight.

Technical stuff

I will, in future, retain the 5 second count data point grabs recently replacing the original 10 second data points in the silver Xcel graphs. In future Rhodium graphs, only the first 300 seconds of decay will be grabbed at end of run counting. This means only 60 - 5 second count periods, instead of the old 120 - 5 second count counts with silver. This is due to the single Rh104 half-life of 44 seconds. (6 X 44) = 264 seconds. The extra time is to assure total decay. I will only have to change two lines of code in the Arduino Uno controller in my "count box" at fusor V. A real snap to change and blow into the Arduino via the USB port

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Neutron detection moderator embedded activation!

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Keeping fusor V busy and blasting rhodium up a bit. I attach the graph of today's run. Got over 100kcpm neutron counts.
Yellow bars are 1 sigma limits

Richard Hull
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RhodiumActivation 11-29-20 1 Sigma.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: Neutron detection moderator embedded activation!

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I feel I must explain the red line in the graphs fully to those not so well heeled in statistics.

1. The Red line is the arithmetic mean, "average", of a full 10 minute long series of 5 sec readings from the un-activated metal probe. A total of 120 individual readings. This is often called "background".
2. To a statistics person, they want to know the standard deviation about the average or "mean" This is the square root of the mean or average value. It is represented by the Greek letter Sigma
3. A one sigma confidence level in the average of a data set. Tells the statistician that the range of values above or below the mean will all fall within plus or minus 67% of the mean or average value of the data set.

I have attached an excel graph of my latest background test, let us look at it. I had the Xcel spread sheet compute the mean by adding all the 120 data point counts to a large number and then divide it by 120. I got the result of the mean or average to be 6.5 counts every 5 second count. However the Sigma is the square root of the mean which is 2.4. Thus 67% of all background measurements will lie between about ~4 and ~9 counts for every 5 second count result. these limits are shown to lie between the two yellow lines.

You can see the span above and below the mean allows for a lot of what was actually measured to one Sigma confidence level. This is reflected in the jumpiness of the data over the entire graph.
This indicates 5 second counts in an already high background area is not really all that great, but does allow a highly visible, if jumpy, indication of the natural exponential decay of the activated Rhodium.

As an example, scroll to the post just above this post. I have added the 1 sigma yellow bars to the result of my 11/29/20 Rhodium activation results This give a better view of when the activation counting ended at about (60 on the graph), 5 second intervals totaling 300 seconds or about after 6 full half lives of the activated rhodium. I will endeavor to continue the one sigma bars in future.

Richard Hull
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Background 11-27-20 5 sec1sigma.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: Neutron detection moderator embedded activation!

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Wow! This is a rolling post....I think I think too much after thinking and posting. (if you can decipher that sentence, you may need help)

Bill Kolb and I have been musing about my charts and graphs. I first noticed, during our discussions the intrinsic wild high count gyrations always seen during the first half life data grab be it Silver or Rhodium. These gyrations were way outside of the 5-6 six count wobble due to the one sigma background range. This is optically visible to the meanest intelligence. Bill mused over it as well. To put off any effort to deal with this to distraction, we left it to "it's what radiation does". It does random real well. It left me a bit uneasy, but we moved on to more pressing issues.

Alas, I was getting a soda after the above posting and a flash came to me. Beta recoil double counting!! I will explain below and in a diagram.

Beta recoil???

I have always loved this and include it in many radiation tutelages which I often I give. See diagram #1.... You can do this yourself. Grab a mica windowed GM counter and hopefully a beta only emitter Tl204 or Sr90 set up the scenario in the diagram and set two lead plates, ( I use tungsten), as shown. Remove plate #1 take a count, then put the plate back in place. Count again. Wow! cool, huh? Given betas of sufficient energy, they will recoil and create soft x-rays that will shine into the detector after impacting a super dense metal. This is beta recoil and bremsstrahlung.

Diagram #2 is the manner in which I think the huge peak variations occur during the first and part of the second half-life of these hot, short-lived, beta isotopes work to do this double counting of the same beta particle! It is partly due to the method of setup in my case.

The reasoning

1. Both silver110 and Rh104 have powerful peak beta energies, (2.87 meV and 2.44 meV respectively). As we know from the beta energy curves, they are not the bulk of the emitted betas but only a small fraction. Most beta energies gather around 0.3 to 0.6 the peak value.
2. Betas can easily travel through thin aluminum, like the shell of my Russian STS-5 tubes. Only the very weakest are lost to counting. Regardless, energy is lost as a beta electron moves through any solid matter
3. Acute angles of impact boost beta recoil as head on impacts with dense matter tend to just stop the beta particle....unless it penetrates the target at reduced energy.
4. From a materials science standpoint, both silver and rhodium are dense metals. These can both readily absorb and reflect beta particles.

I have tried to make the diagram and some of the ray trace keys fairly obvious. I have not covered every possible path, but more to show how double counting might take place.

The upshot is that the blisteringly hot betas that stand a chance of beta recoil, (few), are more likely to be numerous at the T zero in the decay scheme. As the activated material decays the number of hot betas naturally decrease. As the isotope "cools", the normal Sigma of background starts to become more prevalent. For double counting in the silver scenario the hot betas must leave the cylinder penetrate the GM aluminum make a count then re-penetrate the aluminum tube then recoil off the silver again and get through the aluminum again to trigger the second count.

The mass of active silver110 is only 1/2 the activity of the silver by mass. Not so for the Rhodium as 100% of it stands to be activated at its much higher cross section, so double counting is boosted in spite of the two possible unguarded escapes on the sides of the tube without a metal reflector of Rhodium.

I hope Bill likes this idea. Two heads are always better than one and that is a good thing. Anyone else's head have a better explanation?? Debate? Experimenting with radiation and numerous test instruments coupled with reading up on it a lot and often expanding on what you already possess is always to advantage.

Oh, as always, click on the diagram to enlarge it.

Richard Hull
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Beta recoil big.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: Neutron detection moderator embedded activation!

Post by John Futter »

Richard
Change the "beat gun " source to "Beta gun" source in your diagram

but well done
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Richard Hull
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Re: Neutron detection moderator embedded activation!

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Thanks, I often correct later in a clear moment of re-read. I changed "to" in the first sentence to "too" just now. I tend to type faster than I should. Sometimes I re-read posts I've done 3-10 years ago and find faux pas that need to be corrected. Mostly, it is the FAQs.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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Re: Neutron detection moderator embedded activation!

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Attached is Bill Kolb's best fit reduction of my 11-27 Rhodium activation run. He noted the curve is virtually perfect based on the expected half-life decay. I ran two runs on the 27th and attach them here as well

Richard Hull
Attachments
Bill Kolbs best fit 11-27-20 Rhodium activation.JPG
RhodiumActivate 11-27-20 No2.JPG
RhodiumACT 11-27-20.JPG
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Re: Neutron detection moderator embedded activation!

Post by Richard Hull »

Bill Kolb continues his work with me on his now famous best fit analysis of my Rhodium activation. I sent him some of my one sigma results and he has just started to look at this aspect of my activation results In this case, my 11/29/20 best run to date. I attach his results here.

Bill's long term complaint is that due to my high laboratory background average and its one sigma range, the data appears extremely granular to the eye. In his letter to me based on his reduction and one sigma limits, he is forced to admit that in spite of this visual granular nature he finds my results "tight" and accurate as every data point lies within the one sigma limits!! This is rarely seen in such reductions, making my setup capable of securing very reliable data. In Bill's own words In all cases, more than 98 percent of the data points fall within the 1 sigma dotted lines (1 std dev). As you have pointed out before, one standard deviation should contain 68% of the population. This suggests your measurement errors are small compared to the variance in background and Rh104 decay.

All of my Rhodium results are based on runs that never exceed 500- 600k n/s TIER over the last 3 minutes of a 15- 20 minute activation run! Thank you Rhodium!

For the sake of clarity I will now expose the more of less normal run on my uncooled fusor V on the specific run on this best one to date 11/29/20

This long elaboration is for newbies and older fusioneers who have never done activation to show the rather complete process needed to secure all of the activation information preceding this posting over this long thread of Silver and then Rhodium activation. My thanks go out to my long time friend Bill Kolb for his great effort on my behalf.

I get all the gear and pumps up to spec and the mostly "conditioned fusor V" is pinched off from 00 microns on the baratron gauge to 0.1 microns and pure D2 is sent in to a starting pressure of 12.3 microns, differentially pumped, (flowing D2 against the turbo pump working at the pinched or cracked valve.)

What follows are the data taken of over a full 20 minute run on 11/29/20... the numbers left to right...Pressure....KV applied.....mA of current....1 minute timed neutrons count, (CPM), at this level.

12.3 microns......33kv.......9ma......36,467cpm
dito.................36.........12........56,285
12.5................37.........10........60,128
12.7................39.........10........70,008
12.8................40.........11........77,765
13.1................40.........12........81,648
dito................39.........13.5......83,116
dito................40.........12........87,040
dito................41.........11........88,282
13.8...............41..........12.1.....93,203
14.................42..........12.3.....103,622
dito...............42..........13.1.....104,936
14.2...............42..........13.6.....102,864

There are thirteen one minute runs above. the other seven minutes are expended making adjustment to push the next timed count run to new heights. Pressure-voltage-current and new neutron count
In all those adjustment minutes the fusor continues to operate at some level between the last and next timed count. As the fusor is heating all the time, as more power is poured in, and rhodium needs about 3 half-lives at a stable level, we see that after the third or fourth run above the rhodium is decaying as fast as we are pouring on more fusion neutrons. As we keep adding more activation neutrons, The decaying rhodium is still kicked to ever high levels with each run over time. The effort is to grab the best 4 runs near the end when the fusor is at about 110 deg. C.

Power is then cut, and within 1 second, the series of 5 second counts begin. One can see that it is only the last 4 or 5, 1-minute runs, but especially the last one, that will determine the real best activation point of the entire run! Those early runs are effectively lost via decay over time. If you spend a little time noodling on this all will be made manifest. Nothing is to be gained by a long activation run only the last 4 minutes of activation will count. The long run is needed to hit the fusor's peak output, hopefully, more or less uniformly activating over the last 3 minutes.

I attach my personally generated Xcel file created right after the run. I dump the Arduino's 120, 5-second count periods into a text file, then blow this into Xcel on my little laptop to generate the graph. I submit this file should you wish to see the hard count columnar data and graph. (you will need a copy of Xcel to view this one.)

I also attach the jpeg image of Bill's best fit as mentioned above.

Richard Hull



.
Attachments
Bill Kolbs best fit 11-29-20  #2 Rhodium activation.JPG
Rhodium ActCNT11-29-20.xls
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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Richard Hull
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Re: Neutron detection moderator embedded activation!

Post by Richard Hull »

The beat goes on and I just did a super activation of rhodium. See attached.

The lab and all its components were at 32 deg F just now and I have been running the fusor regularly as you know. Coupled with the daily wall loading and a frozen SS fusor, I nursed the system to new heights. I have never broken 100 counts in 5 seconds on rhodium until today. I attach a photo of my "during run" data sheets. I use folded paper bits to record by-the-minute neutron counts. I refuse to constantly type these in as I did last posting. I get two days out of one folded sheet. All might do well to study 12/6 versus 12/7 on these sheets. The pressure at start and the counts at start are noted as they proceed. The ice cold 12/7 results speak for themselves. 12/6 the end run temp on the fusor was 121 deg C. 12/7 super run the end temp was 89 deg C. The results came up fast on the cold fusor making use of the wall loading. COOL your fusors! This is somewhat long known, (some years), but such a magnum impression required Jon and Mark to push the knife into the heart of the matter in their recent cooling efforts. Keep a cool head and a cool fusor and you will do good things and more fusion per unit watt expended.

Note peak 100 counts in 5 sec - 1200 CPM

Click on images to enlarge for old eyes.

Richard Hull
Attachments
Dec7 photo (6)Anno.jpg
RhodiumActivation 12-7-20.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Dennis P Brown
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Real name: Dennis Brown

Re: Neutron detection moderator embedded activation!

Post by Dennis P Brown »

Excellent results - especially using the 'old fashion' method of hand recording data; something I still do. Just nice to see it still is done! Intergrating electrontics for work is one thing, in my home lab, not something I would waste energy on if I can avoid it.

Still, I guess at some point I really need to finish my new fusor and try my hand at Ag activation - especially since I have a new lab building and that I too will use the old tried and true method of recording counts using pencil and paper. ;)
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Richard Hull
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Re: Neutron detection moderator embedded activation!

Post by Richard Hull »

It is difficult to avoid the hand done data. (neutron one minute counts) as I have to adjust after each little run to improve things and this can take a few seconds to nearly another minute before I zero the counter to count the next minute's run. Yes, it could be done at the press of a button but when does the CPU grab and record the instrumented data??? I might start a one minute run at 11 microns, 36kv applied and 9 ma. Then at 21 seconds the instruments might read 11.2 microns 34.6kv and 8ma. I will, in mid stroke, make a correction to add a bit of gas to 11.6 microns, pump it up to 37kv at 11ma. and the last 25 seconds run at this new setting before the one minute count stops and the new count is recorded. My job is to mentally average it all out in the notes. I might write down 11.4 microns, 35kv and 11.2 ma and record the total one minute count shown on the digital display.

The upshot is that most fusor operators of some experience recognize this dance on the part of a good operator. Tough to put this into a simple programming, data collection effort.... Too much meat engine averaging among shifting sands during the one minute count. Like I say, a lot of artifice in among the science.

A complex system could grab all instrument readings each second and at the end of the minute use the averaging based on time integrated operation at somewhat stable points during the minute, then store its best guessed average of all the readings for a recorded and stored pressure voltage and current related to the finished one minute count. I am not ready to do that as long as I have pencil and paper. Actually, in the time it takes to write the data, the fusor is still running and as I look up, I get to start afresh looking at what's going on with the instruments and make intelligent decisions on what to adjust to make the next one minute run more successful than the last.

Folks who have been to HEAS and observed me during a run know what it is all about.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Neutron detection moderator embedded activation!

Post by Richard Hull »

Update to this long posting of activation work by me....
100% of all images and attachments were lost in the terrible backup losses of 2021-2022
I have spent 1.5 hours of my life locating and re-uploading the images. Whew
I felt this series of postings to be instructive. Mostly due to background issues being dealt with and the changeover to Rhodium from silver.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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