Neutron Activation of Cobalt-59 Yields 5.3-year Co-60

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Jon Rosenstiel
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Neutron Activation of Cobalt-59 Yields 5.3-year Co-60

Post by Jon Rosenstiel »

I first reported success with the neutron activation of Cobalt-59 (result was 10.5-minute Co-60m) in these forums back in 2012. viewtopic.php?f=13&t=6300&p=34744&hilit=cobalt#p34744
In that post I had also written about a failed attempt to activate 166 grams of cobalt metal powder in an effort to turn up 5.3-year Co-60.

So now, years later, the Co-60 nut has finally been cracked. On three separate occasions over the past 5-years I’ve managed to neutron activate 822-grams of cobalt metal powder, the result being 5.3-year cobalt-60. The first two successes (2015 and 2018) were done with my spherical fusor, the final (Nov - Dec of 2020) with the cube fusor.

822-grams of cobalt metal powder (obtained from an eBay seller) was divided and poured into two 6-mil poly baggies. (Interestingly, as received, the cobalt powder already had some Co-60 activity) For activation with my spherical fusor the two baggies were stuffed into a Marinelli beaker, the beaker placed in a bucket of water which in turn rested on top of a 1.25” thick UHMW moderator. For activation with my cube fusor each baggie was sandwiched between blocks of HDPE moderator positioned at each end on axis with the cube’s beam lines. For counting on the gamma spectrometer both baggies were stuffed in the aforementioned Marinelli.

Cobalt powder activation timeline:

First activation (Spherical fusor): July of 2015. Five separate activations for a total time of five-hours. Average TIER of 4.8E+06 n/s. Before/after activity increase of ~48 counts/hour.

Second activation (Spherical fusor): February of 2018. Three separate activations for a total time of 3.25-hours. Average TIER of 5.6E+06 n/s. Before/after activity increase of ~46 counts/hour.

Third activation (Cube fusor): Nov/Dec of 2020. Four separate activations for a total time of 2.8-hours. Average TIER of 4.5E+06 n/s. Before/after activity increase of ~64 counts/hour.

Note that even though the cube fusor had the lowest average TIER and shortest activation time it’s before/after activity increase of 63 counts/hour is quite a bit higher than that of the spherical fusor. This can, I think, be mainly be attributed to the cube’s better activation geometry. (Center of my spherical fusor to its neutron oven’s lower shelf is 10.7 cm. For the cube it’s around 6 cm)

Jon Rosenstiel
Attachments
With Marinelli. Shield is 4” of lead with a copper/cadmium liner for x-ray suppression.
With Marinelli. Shield is 4” of lead with a copper/cadmium liner for x-ray suppression.
Business end of my Ortec GEM40P4 detector.
Business end of my Ortec GEM40P4 detector.
Dec 2020 run with cube. Cobalt powder/HDPE sandwich. BC-720 replica fast detector for monitoring TIER.
Dec 2020 run with cube. Cobalt powder/HDPE sandwich. BC-720 replica fast detector for monitoring TIER.
Feb 2018 run with spherical fusor. The buoyant Marinelli beaker required a couple of lead discs to hold it down. Ludlum 12-4 indicating about 58 mRem. (5.8E+06 n/s TIER)
Feb 2018 run with spherical fusor. The buoyant Marinelli beaker required a couple of lead discs to hold it down. Ludlum 12-4 indicating about 58 mRem. (5.8E+06 n/s TIER)
Before/after activity comparison, background subtracted
Before/after activity comparison, background subtracted
Before/after activity comparison
Before/after activity comparison
JoeBallantyne
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Re: Neutron Activation of Cobalt-59 Yields 5.3-year Co-60

Post by JoeBallantyne »

Very cool Jon. You and Joe Gayo are probably the only two people on this site that can currently generate enough neutrons to do this activation in a reasonable amount of time.

Your detector setup for generating spectra is without doubt vastly superior to what anyone else here has.

Joe.
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Richard Hull
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Re: Neutron Activation of Cobalt-59 Yields 5.3-year Co-60

Post by Richard Hull »

Incredible work Jon! Co60 is a big stretch. You are at the outer limits while I am here spending hundreds so that I do the easiest activation on earth. "the Fermi favorite".

I notice the castle. How long have you had it! Where did you get it! We had a bigger one just like it thrown out at our scrap yard `1.6 tons and over a meter in diameter with several layers of copper and cadmium. The mass and the lead alone kept me from any real interest. The yard charges by the current spot for lead. (just around $1.00/lb) Alas, I left it to its fate. It is now gone.

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
Jon Rosenstiel
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Joined: Thu Jun 28, 2001 1:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Neutron Activation of Cobalt-59 Yields 5.3-year Co-60

Post by Jon Rosenstiel »

Joe,

Thanks. For some odd reason I'm driven to find out what makes things tick... and to that end I've collected or constructed the necessary tools to make that happen. From what I can tell I'm not the only one here that has this problem.

JonR
Jon Rosenstiel
Posts: 1494
Joined: Thu Jun 28, 2001 1:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Neutron Activation of Cobalt-59 Yields 5.3-year Co-60

Post by Jon Rosenstiel »

Richard,

I've had the lead castle for several years. I'm guessing it may have come from Los Alamos as I got it from an outfit in Santa Fe, NM. (Don't remember the outfit's name though) Tag on the back says; Applied Physical Technology (APT) Atlanta, GA. Weighs 2450 pounds... about the same as the BMW 2002 had back in the 70's.

JonR
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