Comparison of stainless steel and Zircaloy-2 as encapsulation materials for 252Cf

A comparison is made of the experimental neutron capture background from 3 to l0 MeV of two 252Cf neutron sources, one encapsulated in stainless steel and one in Zircaloy-2. The background of the Zircaloy-2 source was significantly lower than for the stainless steel source above 6 MeV because of the absence of the high energy capture gamma peaks due to iron, chromium, and nickel. Below 5 MeV, the californium fission gamma rays are the major source of interference.