A Source for Caesium-137 Cs137 - Raytheon CK1097-15 spark gap

Archived from radmon.org - originally posted 20/08/2019

I have found a relatively inexpensive source for a Cs137 check source. It is in the form of a 'new old stock' Raytheon CK1097-15 spark gap from ebay.co.uk. (No longer listed - You may find one by searching.) It isn't very active though. I bought it to use as a calibration source for my gamma spectrometer project I'm on with. I tested using a LND712 tube and got about 55 CPM tops (background was ~17 CPM) and had to place the spark gap right up to the end window of the LND712. Whilst not very active it should work well for calibration purposes.

It's hard to photo the printing on the spark gap and had to do so at an angle. I'm assuming the 86-15 part is a date code (week 15 1986) making it just over 30 years old and as the half life is Cs137 is about 30 years it would be literally half as active as when new. It looks like the electrodes were coated with Cs137 and from the pictures it looks like it has either decayed or there is corrosion/oxidization. An interesting find nonetheless.

A YouTube video by RH Electronics demonstrating the CK1097 spark gap's radioactivity: