20th Century Electronics Proportional Counter (ca. 1970s)
This neutron detector was produced by 20th Century Electronics in England. The company began manufacturing BF3 counters in the early 1950s. It is approximately 16 1/2 inches long, 2 inches in diameter, copper walled and filled with BF3. One end (towards the right in the above photo) has a threaded cap to protect the fragile glass insulator.
The model number, marked on the wall of the tube, is 15EB70/50/G/UA0539. The EB refers to "enriched boron trifluoride." The 50 refers to the tube diameter, i.e., 50 mm.
Donated by David Allard.