The Nuclear Heritage Museum (SPCNHI) has recently received a large collection of artifacts from the descendants of Bob MacLanders. Bob began his career with the National Research Council at the Montreal Lab and then joined the move to Chalk River along with the large group of researchers in 1945. His daughter Stefanie (named in honour of Stefan Bauer, a physicist friend of Bob’s at the lab) was born in a Pembroke hospital in 1946 before obstetric facilities were available in Deep River. She recently returned to Deep River to organize an estate sale at the former family home on Frontenac. During the organization of the sale, several exciting nuclear-related artifacts were uncovered, which were donated to the museum. Many of these artifacts are items Bob had rescued from going to the landfill before his retirement in the early 1980s.
One of the artifacts was a mysterious ~ 41-cm-diameter solid “glass ball” that probably dates from the 1940-1950 era. Bob did some glass-blowing as part of his work but what could this curious item be? The ball also featured a neck at one end with an opening ~5 cm in diameter.
Jim Ungrin, the Artifacts Chair for the Society for the Preservation of Canada’s Nuclear Heritage Inc. (SPCNHI), started his investigations by attempting to determine the material. The artifact weighs 5.1 kg and allowing about 5 % additional material for the neck, the volume is ~4760 cubic centimeters. This yields a density of 1.07 g/cc.
The typical density for glass is 2.5-2.7 g/cc which rules out the “fortune teller’s ball” option. Plastics, on the other hand, come in a wide range of densities and plastics that have been used by physicists for the construction of scintillation detectors for detecting and measuring nuclear radiation are much less dense than glass, typically being in the 0.95-1.1 g/cc range.
The tentative conclusion is that this artifact was an early attempt at manufacturing a spherical scintillator. A “crease” along one side of the ball indicates that it was cast in a mold. The integrally-cast neck would very conveniently allow the coupling of a standard 2-inch (5 cm) diameter photomultiplier tube to convert the scintillation light into measurable electrical pulses. In actual use, both the scintillator and the photomultiplier tube would have been painted black or otherwise shielded from any light.
To date the Society has been unable to locate a former Chalk River employee who can confirm these speculations about the construction and possible use of this artifact. Jim Ungrin would be very pleased to hear from anyone who can provide any additional information.
