AECL C0-60 Source (ca. 1950s, 1960s)
This stainless steel dummy source is approximately 4" long and 7/8" in diameter. The following is engraved on the side: "Danger Industrial Nucleonics Co 60 A.E.C.L." The latter stands for Atomic Energy of Canada Limited. Most likely it was produced at Chalk River or their Ottawa facility. Since "nucleonics" is a fairly old term, I am guessing that this source dates from the 1950s or 1960s.
It has two welds, one at each end. The slot at the threaded end (photo below left) indicates that the cap was screwed in and then welded. When you shake it, you can hear some sort of inner container rattle around.
Karl Haff, who at different times headed up ORNL's Source Safety Testing Program and their Radiochemical Processing Program, states that this type of AECL source came in ten or so different sizes and they they were used in a variety of configurations in the AECL irradiators.