Trinitite- activity is zero?

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myID
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Trinitite- activity is zero?

Post by myID » Mon Nov 03, 2008 2:20 pm

Hi-

just bought a Trinitite sample on ebay. Tried to measure something... Seems to be not active at all. Sure I was not expecting it to glow in he dark but still. Did I just buy "some thing that looks like it could look" ??

Thanks

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Richard Hull
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Re: Trinitite- activity is zero?

Post by Richard Hull » Mon Nov 03, 2008 2:41 pm

If the piece is pretty and green then its activity will be very, very low. Such pieces might never show up on a metal tubed GM counter using an analog meter readout. You will need a mica windowed GM counter! I have about 1000 pieces of Trinitite on hand now and am embarking on a study of the material to some significant degree.

There are generalities related to Trinitite that I have worked out over the last few weeks of study and working the material. Several other folks who are trinitite experts are in total agreement with the listing shown below.

This is not definitive as I am still running numerous radiological survey's and other activities to put a fine point on this.

We can say the following with great confidence.

1. On all Trinitite specimens, the larger the surface area, the higher the count. (stands to reason)
2. The more stunning and beautiful a piece is, the lower will be the count for any giving specimen's surface area. A lovely, jade green, glossy specimen that is uniform throughout will read very low, often under 200-300 cpm over background
3. All counting must be done with a mica windowed GM counter to allow even the alpha to be counted. A good digital counter should be attached so that 10 minute counts can establish an honest background count. The mica window must be less than 1cm from the top of the specimen. NOTE* The underside of all specimens can read 10X to 50X lower than the top side. The top side is the pretty, green side and is often domed. The bottom side is always gray when properly cleaned and rather flat with withist pebbles often enbedded in it. A 2" pancake GM detector is almost a must have item.
4. The hottest pieces are disgustingly ugly, unappealing, and a great diappointment to the collector of pretty mineral specimens. The hotest pieces have their domed top sides covered by what looks like a dried wash of mortar mix and are as gray in color as the bottom of the piece. Sometimes a little green shows through but doesn't help the look of the piece at all. The top side of these hot specimens can often only be discovered by the characteristic "doming" noted above
5. A few rather hot specimens that are rather glossy and pretty contain the gray specs all within the surface and it looks as if the pretty green has been salted, ready for eating. However, the hottest of the hot specimens are almost pure gray with perhaps only traces of green.
6. All trinitite is green at the core! Surface greens range from light green to a green so black that the green is only a trace. Most pretty trinitite is a darker jade green in color. This is the most prized by collectors.
7. All trinititie is broken at the edges. When viewed edge on, it looks like a beautiful emerald crystal sponge with large air pockets like baked bread.
8. Some rare pieces of trinitite will float! (density less than one and a number of pieces are almost neutrally bouyant or sink slowly in water.
9. Black inclusions are attributed to iron and steel from the vaporized tower, while lovely brick red inclusions that can even look ruby like in the green melt is attributed to copper from the site's vaporized wiring and signal lines.
10. Gamma spectrograhic analysis and geiger counter surveys have shown that only the following items can contribute to a radiological examination in a significant way. It order of decending activity.


Americium 241 (gamma , alpha)
Cesium 137 (beta)
Baruim 137 (gamma) Cesium daughter product
Strontium 90 (beta)
Europium 152 (gamma)
Cobalt 60 (gamma)
Possible Uranium and daughter components from bomb's tamper (alpha, beta)

11. I have found that after washing trinite in a mild acid solution and using a tooth brush to scub it, then neutralizing it in a mild base and rinsing and drying it, NONE of the original alpha activity is lost!! This means all surface alpha was long ago washed off in the rain that fell between 1945 and 1952 when the bulk of all the trinite that is for sale was removed from the bomb site. There is a real fascinating story here regarding the original surreptitious removal of all the public domain trinitite for those who care to investigate. We have one single man to thank for our having any trinitite at all to buy or sell.

12. Virtually no amount of cleaning of dirty trinitite will wash off any of its radiation. This includes a toothbrush scrubbing of pieces soaked in Oxalic acid for 20 minute and neutralized in a mild caustic wash and then rinsed off in water. (I have measured the evaporated residues from the acid and caustic washes used to clean up to 40 specimens at one time to find virtually no activity present)

I am investigating to see if most of the Beta activity is due to the uranium daughter Protactinium (Pa234). After all, there was tons of U tamper in the device.

The light grey covering of the hottest pieces may contain 90% of the piece's activity. Without this over coating, I fear the piece might just be another pretty piece of trinitite. We will see.

I have found that by careful counting, using my 2" mica windowed, pancake and digital counter, lovely green specimens larger than a quarter coin can read about 200-300 cpm above background. At the opposite end of the spectrum a rotten, ugly, gray piece of rubble, the size of a tiny pea, will read 4500 cpm over background. I hope to understand this mystery before my work is over, or, at least develop a theory.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Trinitite- activity is zero?

Post by myID » Mon Nov 03, 2008 3:23 pm

Hi Richard-

I have just a crappy GM counter, so I always use scintillation counters. Checked the count rate- almost no difference and also did a spectrum analysis with almost no difference to background...

Thanks anyways
Roman

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Richard Hull
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Re: Trinitite- activity is zero?

Post by Richard Hull » Mon Nov 03, 2008 3:42 pm

Trinite is still too undervalued to try and fake it, just yet. Given another 100 years and faked Trinitite will abound, once the fission products have faded to virtual obscuirty.

You should take a pix of your specimen and post it. Wash it carefully to get rid of any dirt and debris. I use a wash of weak oxalic acid and, with latex gloves on, gently tooth brush it to remove any rust stains on the piece. I next transfer it to a baking soda bath to neutralize the mild acid. and finally to a warm water bath to rinse it. Once cleaned, the piece will take on a new life of its own. BE CAREFUL!! The stuff breaks easily. Be very gentle.

Your piece may have already been cleaned prior to purchase.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

myID
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Re: Trinitite- activity is zero?

Post by myID » Sun Nov 09, 2008 7:08 pm

Hi Richard-

here some pics- not too impressive But I guess it was cleaned before I got it....

Anyways-
Greets
Roman
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Doug Coulter
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Re: Trinitite- activity is zero?

Post by Doug Coulter » Sun Nov 09, 2008 11:24 pm

Richard,
I can kinda back up one of your observations. BillF brought over a pretty
green sample that we tested and found it to be little if anything over background
here. Haven't tested the other sort, and our measurement would have
taken 10% or more over background to register positive.
Just a data point.
Pic of it if anyone wants the bandwidth.
Why guess when you can know? Measure!

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Richard Hull
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Re: Trinitite- activity is zero?

Post by Richard Hull » Mon Nov 10, 2008 3:47 pm

The historic nature of Trinitite makes it a unique treasure to more than just the average mineral collector. Radiologically, it is not very interesting as it is not something to make a GM counter sing like as a nice chunk of uraninite or as pretty as Carnotite or Torbernite.

Maybe someone here can fill in the blanks for me. I was assuming that the tamper/reflector of the Trinity gadget was made of DU, but have learned that the tamper reflector, "tickling the tail" experiments in 1945 were done not with DU, but Tungsten carbide! Did they use WC in the gadget?! It would seem amazing to do all your criticality experiments with one substance and then build a bomb around another.

If they used WC that might explain why little U is found in Trinitite. It just seems odd that a ton or more of U tamper is not seen radiologically in trinitite. Little of any tamper is burned. Almost all is just vaporized.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Trinitite- activity is zero?

Post by hjerald1 » Mon Nov 10, 2008 8:19 pm

Hi Richard,
According to "Atom Bombs" by John Coster-Mullen, page 47: in discussing
the plutonium capsule loading into the interior of the Trinity gadget, "the capsule did stick as it entered the uranium tamper". (This was due to the heat of the plutonium in the capsule causing the capsule to expand so it would not go in all the way until waiting a period of time for the parts to cool....I guess from ambient air cooling of the capsule surface as the Pu core would certainly not cool!)
I read this to mean that U was actually used in the Trinity Gadget (as well as in Fat Man........ which is described on page 39).
At least some portion of the U was consumed in energetic neutron fission of the U-238, which was stated to have contributed ~20% to the yield of the Hiroshima device.
Jerry

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Re: Trinitite- activity is zero?

Post by hjerald1 » Mon Nov 10, 2008 8:28 pm

In Fat Man, the U-238 tamper is reported to have been 9.0" in diameter (am guessing this is not a misprint as this was surrounded by and 18.5" sphere of aluminum (pusher). No thickness was listed for the U sphere, but does seem that your thinking of a ton or more of of U may be an over estimate.
Jerry

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Re: Trinitite- activity is zero?

Post by Richard Hull » Tue Nov 11, 2008 2:12 pm

Jerry, Thanks for your thoughts on this. I will have to check other books that I have to research this a bit more. "Critical Assembly" would be the ultimate reference book. I'll check it.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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