New Rhodium counter system and moderator for fusor V

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Richard Hull
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New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

There is nothing better than jamming your neutron oven for activation right up against the Fusor. Better still, for fast activator elements with rapid decay times, is burying the detector surrounded with the activated element for quick counting after the fusor is turned off.

I have decided to make a moderator right hard up against the fusor V. The moderator is made up out of HDPE blocks cut from 1x1 and 1x2 HDPE. The detector and rhodium are placed in a 5/8-inch bore hole in a 6-inch long 1x1 block of HDPE.

Pictures are worth a thousand words....Below, find a diagram of the assembly and a few photos that are annotated to explain what you are looking at.

I will test this once I get my fusor reconditioned to the point activation that can be measured to compare to the old huge moderator rhodium activation separated well away from the fusor V.

Richard Hull
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Rhodium GM setup 2021.jpg
Rhoduim and GM raw.jpg
Rhodium and GM done.anno.jpg
Rhodium moderator.anno.jpg
Rhodium moderator1.anno.jpg
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Re: New Rhodium counter system and moderator for fusor V

Post by Finn Hammer »

Richard,

That looks like a neat way to get the results pronto! Perhaps something I would like to replicate one day, with a pancake sensor and a disk of someting exotic.

Cheers, Finn Hammer
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

It doesn't get much more exotic than Rhodium!! Nothing activates faster with a huge cross section! Rhodium is 100% Rh104. It has two drawbacks....1. Cost (currently $18,000/troy ounce) and its non-availability in foil and very thin sheeting. 2. While its short half life (42 seconds) is great as it will saturate to its maximum radioactivity in under 5 minutes exposure in any neutron flux, it forces the fusioneer to embed it in intimate contact with a GM counter in a moderator near the fusor. The user must, within seconds after fusor shut-down, start a recording counter to gather data. I have registered a 2x increase over background just yesterday in my new setup at only 30,000 n/s TIER1. I exposed it for 5 minutes. I am stunned how nice the activation is now that I have jammed the Rhodium up against the fusor in the block moderator.

Rhodium's chief advantage remains its very high cross section in a 100% isotopic form. I was lucky to find a fellow element collector who had some tiny bit of sheeting he was willing to sell when Rhodium was only $10,000/troy ounce. It rose recently to over $28,000/troy ounce, but has plunged down to about $18,000 of late.

I have a significant gamma background in my lab. As such, the thin aluminum bodied Russian GM tube I use to count the Beta emitting Rhodium activation is perfect. The very hot Betas go through the aluminum body with ease due to close proximity, while any gammas tend to whistle right through, undetected, due to the low Z of the Aluminum body. A nice large 2-inch mica windowed pancake is much more efficient at detecting gammas as its thick steel body will allow for photo and Compton emitted electrons back into the volume to be counted. Thus, a steel bodied pancake is not a great choice for moderator embedment with a beta emitter in a high gamma field. HDPE is not a good gamma blocker.

The Aluminum GM body has an extremely low cross section and will not activate to a degree of interference in counting the Rhodium.

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Attached is tonight's run. I activated the rhodium in the new setup for 4 minutes at 56,000 n/s TIER. The other night I got the peak of 2X the average back ground with 30,000 n/s TIER. The Excel graph should be self explanatory to graph readers. The peak count was 25 counts during the first 5 second count interval and that is a bit over 4X average background and subsequent count remained above the average background for 100 seconds (2 half lives)

I am still nursing fusor V back to life. It looks like anyone with rhodium need only have a GM counter to prove fusion with intimate moderator contact doing only 30,000 n/s TEIR (2X background) with 4X background at 50,000 TIER.

Richard Hull
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RhodiumActivation 7-6-21.jpg
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Re: New Rhodium counter system and moderator for fusor V

Post by Joe Gayo »

Rhodium is really the cat's meow. The sensitivity might have some interesting uses as a compound for detection if other radiation could be discriminated against.
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Yes, the 100% isotopic abundance of Rh104 and very high cross section coupled with the 42 sec half life make Rhodium an ideal activator. (fermi's favorite metal) A water soluble compound of Rhodium dissolved in a squat 1 liter jar would be its own moderator. Unfortunately, a Rhodium compound based on $18,000/oz. price tag would probably be amazingly expensive, per atomic percent in solute, over the metal. As it is a beta only emitter, a liquid moderator would be a far better for a soluble Indium compound that could be a gamma emitter and counted with a PMT. Carl Willis did a great saturated manganese sulfate liquid moderator readout with a PMT many years ago.

Rhodium in a moderator needs the foil metal in intimate contact with an aluminum bodied GM detector. For your hot system, placing the moderator at a bit of distance would eliminate the significance of aluminum activation while really doing a super high count Rhodium activation.

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

The results seem to be in for now. I am getting better counts with my small moderator jammed up against the fusor at a given TIER than my giant moderator of 10X the volume of moderator merely 2" distant.
At 86,000 n/s Tier the average of 10 sec peak counts was 25 in the giant moderator. The close in small moderator was 33.

The big moderator is still used with my long 3He tube, of course.

An image of last nights results.

Richard Hull
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Much cleaner than of a few days ago. Remember, at 200 seconds Rhodium is dead after 5 half lives. (that is 40 on the time line)
Much cleaner than of a few days ago. Remember, at 200 seconds Rhodium is dead after 5 half lives. (that is 40 on the time line)
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Last nights efforts.

I am concerned that due to the above average axis counts at 40 (200 seconds), there might be a second very weak activation. I doubt it is the aluminum walled tube (far too low a cross section for the TIER).
There are copper lead-in wires running along side the tube body to carry the negative lead deep into the block. Copper is higher cross section but there is very little mass of copper in there. The surface area of the aluminum walled tube grossly predominates over all of the metals within the detection block.

I will have to do more TIER before anything becomes more apparent regarding a second activation which might be occurring.

It is now, as always, apparent that Rhodium is indeed the easiest of all the elements to activate with a weak fusion system that can't be run for many long minutes. It just happens to also, at present, be worth more than 15 times the price of pure gold. Thus, silver is still king for GM detection with Indium a close second for weaker systems. The value of a quick activation beta emitter of short half life is that the GM tube can be in intimate contact with the foil and buried within the moderator for instant peak reading.

Those looking to Gamma spectrometry will need a lot of neutrons and longer exposures to create radioisotopes of longer half- life so that the activated item can be extracted from the moderator and transferred to a nearby gamma spec setup within a reasonable time period.

Here is where those working over 10e6 n/s TIER with extended bombardment times can really shine.

Richard Hull
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RhodiumActivation7-9-21.JPG
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Todays run near10X peak over background. The counting seems to settle down near background only after 90 X5 = 450 seconds. (7.5 minutes) Something else there after 40X5 = 200 seconds when the Rhodium is as dead as 4 o'clock?? Could be nothing, I guess. Still not hot enough TIER to discern.

The higher and higher daily peaks, due to graph scaling needed to capture the peak, make the noise about the red average line look greatly less prominent. To be expected, of course.

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Re: New Rhodium counter system and moderator for fusor V

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The backgrounding I have used is the average taken from 200 seconds to 600 seconds. I noticed a tendency of there to be counts above background as calculated in Excel between 200 and 600 seconds.
I decided to increase my lead shielding around the moderator with the GM to reduce background count. I further decided to run a background average just prior to an activation run taken over the entire period of 600 seconds and get Excel to average over that entire period for a true background. This translates to a Gamma only count of 4.4 x 12 = 53cpm! This is due to the fact there are 0 alphas and 0 Betas able to reach the deeply buried GM tube in my lab.

I present that background below.

I immediately ran an activation run on the Rhodium. It turns out that it yielded an activation at 293,906 n/s. Unfortunately, I was forced to reset the Arduino counter and lost 6 seconds of peak count time. I supply this graph below but have used the earlier background level of 4.4 counts per 5 second count. We see what is now a much clearer picture that something else is activated, maybe. Is this of any significance? Any ideas here? Large Aluminum sheeting area in the GM tube?

I also include images of the new lead shielded region about the GM activation moderator block.

Richard Hull
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GM BKGD 7-11-21.JPG
RhodiumActivation7-11-21 mod.jpg
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Latest activation on Wednesday. Notice the background doesn't seem to stabilize until about 90X5, 450 seconds after activation.

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

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Activation graph taken today is interesting.

I have been stoking the fires of fusion here and doing my Xcel graphs as usual. I have noted a failure of Rhodium104 to die a natural death at 5 half lives after activation. At first I thought I was activating the Al 27 GM tube shell. The extended above background looked like it, but its miserable cross section of 0.23 barns is just too low as compared to Rhodium 103’s 144 to make Rh104. I rechecked rhodium in the gospel, (table of the isotopes book ), and Lo and behold, Rh103 has an additional cross section of 11 for making Rh104m with a 4.4 min half-life. Unfortunately, it decays by isomeric transition which means gamma and not betas. However, once again, 47% of 104m emits a low energy x-ray of 51kv which the thin aluminum shell would indeed allow for detection directly into the counting gas. Thus I count mostly betas from Rh104 and then
am left with counting only weak x-rays from Rh104m and only about half of the 104m radiation is counted.

Before you might think I point out the late big peak, No! I am pointing to the green box which appears to hang above the average red line as being Rh104m decay long after Rh104 has gone through it predicted full 5 half-life decay represented by the blue line well below the average background!

I attach the graph with annotations. (click to enlarge to read)

Help me put this issue to bed with wise comments.

Richard Hull
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RhodiumActivation7-22-21 special.jpg
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Re: New Rhodium counter system and moderator for fusor V

Post by Jon Rosenstiel »

Richard,

Maybe not of much help, but interesting nonetheless.

Some years back when Carl's fusor was down Carl and I got together here in my lab in an effort to neutron activate 150 ml of rhodium plating bath. Carl's plan was to activate the plating bath and look for evidence of Cherenkov radiation produced by Rh-104's 2.4 MeV beta. We had no luck with the Cherenkov, but I did manage to get a nice gamma spec from Rh-104m.

In the below image Carl is attempting to activate a rhodium self-powered neutron detector. (Too little rhodium so that didn't pan out either)
https://www.oecd-nea.org/science/rsd/ic96/4-2.pdf

Jon Rosenstiel
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Gamma spec
Gamma spec
Carl at the controls. Rhodium plating bath in the foreground.
Carl at the controls. Rhodium plating bath in the foreground.
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Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

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Wow, that plating solution must have had single milligram amount of chemical spread out throughout the liquid!! Nearly 5 million n/s TIER! I had probably 2000-3000 times the mass of Rhodium metal in one spot compared to what you guys were using. You did catch the 47% x-ray 51kv claimed by the table of the Isotopes. I see you also captured a 20kev x-ray not mentioned in the book. I certainly would have to include that in my Rh104m counting routine as an additive.

I think that 21kev and 51kev x-rays would defeat the thin aluminum shell and blast photo and Compton electrons into the GM tube's gas volume to be counted. I feel this backs up the Rh104m supposition following the death of the heavy beta emitting Rh104. I feel this is due to luck of the draw as the Russian GM tube was in intimate contact with metallic rhodium even though the TIER was in the region of only 3x10e5 n/s

Thanks for the heads up. I think that you had plenty of neutrons, obviously, but not much Rhodium in your and Carl's experiment. Good ole Carl....I miss th' boy.

I kept boasting of the Rh103 100% isotopic purity and x section of 144, only to later find out it had two cross sections 144 and 11 making two radioactive byproduct isotopes. At least they are additive in the counting right along side one another until the fast burning Rh104 dies out. What little Rh104m I make is also rather depleted at 30-40 on my x axis (150-200 seconds).

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Jim Kovalchick »

Richard,
You might recall I posted about Rh 104m in the past. I mentioned that getting it to saturation could be tougher. That makes it a tougher nut to analyze. At the time you were primarily interested in the shorter lived beta emitter.

viewtopic.php?f=13&t=13867&hilit=Rhodiu ... =10#p90602
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Jim, I would suggest you take another gander at that chart. The numbers are based on mass of the target relative to Aluminum which they use as the standard at 1.0 gamma relative. Aluminum at a cross section of .235 and is much more difficult per unit mass-relative to activate than Rhodium!

So, to get the same relative gamma output under thermal neutron bombardment at "X flux" with 1 gram of Al you would only need .03 grams of Rhodium! or 1/33 gram of Rhodium. Some time, it pays to read the fine print asterisk below. I have often touted Dysprosium due to its massive cross section. Dy is .01 in the chart; you only need 10 milligrams of Dy to equal 1 full gram of Al. Unfortunately, Activated dysprosium has a long half life, (gotta' keep it in the oven a long time), and is only about 28% of the element with a cross section of 800 and 2000 respectively, which is stunning!

The chart is taken from real data I am sure, but just looking at cross sections Al/Rh .235/11 you get .02 for Rh104m. So if you want gammas related to the chart, go for something of really low value, deep below 1.0 in the chart's right hand column, but be ever mindful of the half life. We cannot do a .002-relative, with a 16 year half life.

In the end, I do indeed seem to have an Rh104m tail signature in my activation strictly due to the large volume of weak x-ray output that a GM can and will detect. I typically run near the quoted TIER in my chart for a 6 minute time period.

Thanks for re-referencing the chart! I copied it off to my reference data files and printed it out. A great quick check chart if gammas are what you are going for. Indium is great for gammas if you have the operational time or a heavy flux with your fusor. Even though I have a great gamma spectrometer, gammas are out for me due to the short half-life stuff I am limited to and the instrument being a 20 second hike from my fusor to the spectrometer. The fusor lab hits deep sub-freeazing temps in the winter, so the gamma spec is in the upstairs lab where stable temps are conducive to long life on the NaI:Tl crystal.

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Jim Kovalchick »

Richard,
My point is more basic. I pointed out that Rh activation was more complex than the single isotope activation you were exploring. Your response back then pushed it off as insignificant, and now I read that you are using the same isotope I pointed out previously to potentially explain a longer decay than you expected.

The chart I had provided comes from Ortec and was designed to help with activation analysis with gamma spectroscopy. It is only so relevant for a Geiger that looks at betas better than gammas, but as I pointed out originally, the Geiger will see some gammas including those from the other Rh activation product.That's all I was trying to say then and now. No need to refer me to the fine print 😀
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Re: New Rhodium counter system and moderator for fusor V

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Thanks for clearing your original thrust up for me. The Russian tube is perfect for the Rh104m counting in intimate contact only due to the heavy output of its whimpy x-rays, I assume the claimed x-rays are nuclear in origin and not shell types. Wiki gives the following highly variable statement.

"Gamma rays and X-rays are both electromagnetic radiation, and since they overlap in the electromagnetic spectrum, the terminology varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: Gamma rays are created by nuclear decay, while in the case of X-rays, the origin is outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma ray astronomy, while radiation below 100 keV is classified as X-rays"

The reading of the fore text in the isotope book give little added info. However I see no L preceding the x-ray notation so I assume these are nuclear (gamma/x-rays).

I would, in the case of isotopes, to have all EM radiations from the nucleus classed as Gamma rays regardless of energies. X-rays should be of shell origin, for my tastes. In the end, regardless of verbiage, I am counting weak Rh104m electromagnetic photons and not any associated beta, (only 0.18%).

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

The fusor is doing better and the last run appears that the RH104m is very clearly above the noise/background average level.

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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

This is a discussion of the graphs and complex two level decays. Silver and Rhodium have this complex decay scheme due to completely different reasons.
Silver has two distinct natural isotopes that each have high cross sections. These co-jointly activate and decay.
Rhodium has only one natural isotope with two different cross sections to create two new co-jointly produced isotopes. These new isotopes co-jointly activate and decay.

Now to fully explain the two rhodium activations and related decays.

This is a very complex issue and one that needs to be explained to some modicum of understanding.

1. Regardless of the neutron fluence, both RH104 and 104M grow or activate together based on their relative cross sections and half lives. Saturation at any flux, for any activation of any isotope demands a minimum of a 5 half-life exposure of the isotope to be activated in a stable neutron fluence. Saturation: the maximum radioactivity that can be induced in any isotope in any fixed thermal neutron fluence.

2. The Rh104m "grows in", (activates)much more slowly than the Rh104, again, due to its reduced cross section and its much longer activation time which is 6 times longer to activate to that lower level than Rh104 to any given neutron fluence.

3. Thus, if it takes 4minutes operating at lower levels of fluence to arrive at a ”peak activation level”, pressure, voltage, and current wise, both Rh104 and Rh104m are at some fairly low level of activation with Rh104m at a much lower level that Rh104.

4. At this 4 minute point, the system is run at top fluence for another 4 minute to peak the Rh104 to it absolute full saturation over this period, (5 half-lives). Only now is the fusor turned off and the counting actually begins.

5. Decay is now the ruling factor. Rh104m is no where near saturation, requiring 22 minutes at full peak fluence to saturate. This means that the Rh104m is just 0.9 half-lives towards a peak 5 half-life, 22 minute saturation. While Rh104 is absolutely at peak saturation.

6. Yes, from the very first, the fully saturated Rh104 betas and the not saturated Rh104m weak gammas are “summed” in the decay count!
7. This is a complex curve out to about to 200 seconds but is far more representative of the Rh104 decay due to saturation.
8. At ~200 seconds, all of the Rh104 is dead!! From 200 seconds on out to the 600 second data collection limit, Only the Rh104m decay is recorded.
9. Due to the lower level, non-saturated activation of the RH104m, its decay drifts into the background level after about 500 seconds or less.

It can be seen that a very long buildup time to peak, say 12 minutes, will almost saturate the Rh104m to some low level, but the extra 4 minute of operation at peak to saturate the Rh104 will still not saturate the RH104m to anywhere near saturation in the peak fluence in the small 4 minute longer run.

However, this longer time to peak will mean more counts from the Rh104m over the long 600 minute graph time due to the lower level saturation of the Rh104m over the 12 minute buildup run time. This will show up in the decay of the Rh104m going to be above the background even at the end of the graph’s 600 second display. This is a very rare occurrence as I can get the fusor up to peak in about 4-5 minutes with another 4minutes at peak needed to saturate the Rh104.

If all of the above seems confusing, it is the way of the world of radiation physics. Newbies will only understand it with study and application, at which point the concepts will be owned for life.

To the non-mathematical newbie.....When reading a graph make sure to read the legends on the two axis to observe what the numbers on them relate to.
Examples related to my graphs above..... At 40 on the X axis this is 40 x 5 = 200 seconds after the count began. At 90 on the y-axis, a 5 second total count of 90 counts were registered. This means that at that point 90 x 12 = 1080 cpm was the decay rate at that moment in time.

Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Finn Hammer »

Richard,

Thank you for a comprehensive detailing of the decay curves.

Edit:
I read the numbers wrong in the silver section of this analogy, and this lead to a lack of, well, analogy.
In short, I misstook the half life of Ag107m instead of from Ag108 and this removes the basis of any analogy.
Sorry for that, better luck next time.

Just disregard the rest of this post:
--------‐--------------------------------------------------------
In a way, (Although not at all) it is like activating a sandwich of 2 different metals, one with a large neutron capture cross section and a fast decay, like silver, together with another metal with a small neutron capture cross section but with a slow rate of decay, like copper.

In this analogy, I discard the 69% of Cu63 because it produces Cu64 with a 12.8 hour half life and thus does not come up to detectable levels within the short run times we use here, instead base the analogy on the 31% of Cu65, which turns into Cu66 with a 5 minutes halftime and a neutron capture cross section of 2.3 barns.

In this analogy, the 2 silver isotopes Ag107 and Ag109 which both have comparatively large neutron capture cross sections, 35 vs.89 barns, and relatively short decay half lives of 44 sec. vs. 39 sec. and due to the close coincidence in decay time, they will look almost identical on the graph.

With a run time at max. flux of 45x5=225 sec. the silver isotopes have been brought up to the full level of saturation that the present flux enables, whereas the copper is only within 13% of the saturation which it would take 25 minutes to reach.

Measuring the combined decay profile would yield a similar profile as the Rhodium decay, where the silver decays to near zero in 225 seconds after which the copper dominates for another 22 minutes.


As a note to your axis labelling, I find it unnecessarily complicated that you label the x-axis in multitudes of 5, (so that 4 divisions of five denoted as 20 really means 100) I would like to see the time in seconds directly.
Similarly on the Y axis: why not just label it in CPM directly? Just my 7 cents.

Cheers, Finn Hammer
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Re: New Rhodium counter system and moderator for fusor V

Post by Jim Kovalchick »

I find this diagram helpful in understanding Rh activation and decay. The Rh 104m stuff muddies the waters because of it does not release betas (at first) meaning that even if your detector sees the gammas it likely won't do it with the same efficiency. Ultimately Rh 104m becomes Rh 104 and then will decay with betas. This latter part probably won't be seen unless you activated with big flux and/or your background is very small. I know that deep in the caverns of my brain is the knowledge to write up the time function curves for activity of each isotope, but I am afraid of what else I might find in there if I go looking.
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Richard Hull
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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Thanks for posting this update, Jim. This decay diagram is far more elucidating than the complex diagrams at the rear portion of the table of the isotopes. It was hard to get it in my head that as RH104 was being made, (my super hot 2.4 MeV beta emitter), the 104m was also being made, but as noted, to a far lesser degree. What was tough for me was that the Rh104m would also decay into Rh104. Due to the weakness of activation of the 11 cross section of Rh104m, the muddiness is bad, but not terrible so far as my graphs of 10minutes, (600 seconds), are concerned. The trail-on betas from Rh104m decaying to Rh104 would be far fewer than the 144 cross section of promptly produced Rh104 would be. Still, it is rather bizarre. It turns out far more bizarre than silver's double decay. Rhodium remains the number one fast 100% isotopically pure activation metal of choice.

It is to be noted that at the death of Rh104m there would be a barely detectable beta only signature of Rh104 going on for another 210 seconds until this tiny Rh104 emission would cease. (to be detectable to any counting agency)

It is important to remember that, due to the exponential nature of radioactive decay, in theory only, no radioactive would ever cease to decay. The half-life is a convenient, measurable, calculable value convenient to our linear brains. Nature loves and nurtures the exponential while shunning the linear.

This is about as complex a story of activation and decay as one might encounter with a low grade neutron source which might be actually observable at the amateur level.

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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Re: New Rhodium counter system and moderator for fusor V

Post by Richard Hull »

Re: Finn's posting....The silvers have far different decay times for the product isotopes of Ag108 of 2.4 minutes, (144 seconds) and Ag110 of 24.4 seconds. I think you are looking at the metastables which cannot be produced via neutron activation of silver. (look at the method of production column for the two silver metastables). Sometimes if the item immediately below the stable activation element is a metastable it can't be produced by neutron activation. In the case of the silver metastables they are only produced by the decay of a cadmium or Ag metastable radioactive isotope. There are catch 22s in this biz. In the case of stable silver 109 there is a cross section of 3 to neutron bombardment to Ag 110m with the incredibly long half time of 255 days! Needless to say, this nice beta emitter will not be activated or seen at the normal exposure times by the amateur. As a point of amusement, you will note that like rhodium, the production of Ag110m will see it decay to Ag110 the original product of Ag109 with the high cross section.

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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Re: New Rhodium counter system and moderator for fusor V

Post by Jim Kovalchick »

With Rhodium I wonder if activating only to saturation of Rh 104 would help clean up the muddied decay back end. In others words, after 5 half lives of Rh 104, stop activating and prevent Rh 104m from catching up to it's potential relevance.
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