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First attempt at activating Indium

Posted: Wed Jan 01, 2020 9:32 pm
by Mark Rowley
The past few days I’ve been working on indium activation with my Fusor. To do so, I assembled the following:

6x6” paraffin moderator cut in half
1.5x1.5” sq indium foil
LND7311 pancake at 900v
Nucleus 500 digital scaler

The indium foil was placed between the two 3” paraffin halves and placed 8cm from the Fusor. This would place the indium approx 16cm away as it was in the center of the two paraffin halves (see pic).

-Pre activation background-
The LND7311 registered 359 normal background counts in 10 minutes which equates to 35.9cpm. I conducted the same background assessment two other times which resulted in a ~5cpm difference.

-The run-
The Fusor run consisted of:
5 minutes
43kV
3mA
40mTorr D2 pressure
3.45e5 isotropic n/s
6.91e5 fusions/s

After the run was completed and with the fusor input voltage switched off, the LND7311 pancake registered the following numbers:

Timed 1 minute counts:
1. 103cpm
2. 69cpm
3. 64cpm
4. 60cpm
5. 56cpm

It seemed to stagnate around 50-60cpm but slowly decayed to 40cpm after 1 hour.

Here’s a YT video of the first 2 minutes.

https://youtu.be/3J3jUPI_FPw

Any comments, criticisms, etc welcomed.

Mark Rowley

Re: First attempt at activating Indium

Posted: Thu Jan 02, 2020 12:45 am
by Richard Hull
Great work! This is classic activation and only real thermal neutrons can do this. No real-time fallible electronic detection needed. Post bombardment proof that neutrons were produced.
It is a pity that most first pass efforts at fusion rarely make enough neutrons to produce enough activation outside of questionable statistics. it takes a bit of running of a fusor and learning how to handle it to get the numbers needed to make activation a fete accompli

Richard Hull

Re: First attempt at activating Indium

Posted: Mon Jan 20, 2020 5:52 am
by Joe Gayo
Nice work Mark.

Here is my first gamma spec measurement.

- Indium Foil (100x100x0.1mm) sandwiched with 100x100x50mm LDPE blocks.
- 120sec exposure
- 1in^2 NaI Detector, 900V, 1000sec count
ADE1A604-0DC9-4E44-B4A7-5E08CD141E73.jpeg
1000sec Indium Spec

Re: First attempt at activating Indium

Posted: Tue Jan 21, 2020 1:44 am
by Mark Rowley
Thanks Joe.
My gamma spec arrangement is currently in the house but I hope to get another setup in the workshop sometime soon. Capturing telltale photopeaks from activation work would be most interesting and has been on the to-do list for awhile now.

Mark Rowley

Re: First attempt at activating Indium

Posted: Tue Jan 21, 2020 7:12 am
by Richard Hull
Great work! Activation is a lot of fun and is one of the key benefits, for me at least, in having a fusor in the first place.

Richard Hull

Re: First attempt at activating Indium

Posted: Tue Jan 21, 2020 12:50 pm
by Jim Kovalchick
Nice work Mark! When I read that you used big blocks of parafin, I was reminded of a historic treasure I recently visited in Munich. At the Deutsches Museum, they exhibit Otto Hahn's lab desk complete with version of Meitner's experiment that first measured fission, complete with a big block of wax. Consider yourself in esteemed company!

Jim K