Radon Graph of NBS SRM De-Emanation

This graph shows the result of de-emanating a National Bureau of Standards Radium solution into a 3.6 liter cylinder. We where fortunate to acquire a 13.2778 Bq National Bureau of Srandards SRM 4950 #29 back in 1986 before Radium was so strictly regulated. The unusually high efficiency of these cells is because the quartz windows are lightly coated with zinc sulfide phosphor.