Sc-46 Spot Irradiator
The spot irradiator makes use of a source collimator to enable in-situ radiation-damage testing of an electronic device while minimizing the dose received by other devices nearby on the test board. The irradiator uses scandium-46 created in the reactor from irradiation of Sc-45. Sc-46 decays with an 84-day half-life, emitting 1120 keV and 889 keV gammas. These gamma are hard enough for useful electronics damage testing such that they can act as a surrogate gamma emitter for Co-60 that can be tailored for use in enhanced-low-dose-rate-sensitivity (ELDRS) testing. The Sc-46 sources can be activated for dose rates in the range of 1 -10 mrad (Si)/s, which is the typical desired range for ELDRS radiation damage testing of electronics.
Note that the test cavity is 7" wide by 9" deep. The slots that hold the phenolic support piece are 1/8" high and ¼" wide. Therefore, the support piece should be 7.4" wide by no more than 8.9" deep and less than 1/8" high. The circuit board on which the parts are mounted can have dimensions up to 6.9" wide by 8.9" deep, but the area of the board on which parts are mounted should be kept to 6" wide by 8" deep.
The figure below shows the approximate falloff of dose rate with distance from the center spot.