Cold Beryllium Source
Cold Beryllium Source was our first experience in creating a cold
source at the reactor. The problems of radiation safety and heat removal
were solved. The source was placed at the center of the reactor core where
the thermal flux was 1.1014n s-1cm-2. The specific radiation heating was 3 W/g. A helium refrigerator was used to maintain the 400g beryllium at a temperature of 20-30K. The vertical polished stainless steel guide provided
an intensity of 2.104 UCNs at its exit, the gain factor being about 12. Our next step was to use a hydrogen moderator to obtain a much higher gain factor.