The production of *sp81m*Kr generators at the Oslo cyclotron

The techniques developed for the production of *sp81m*Kr(13s) ventilation generators at the Oslo cyclotron are described. The procedure is based on the reaction *sp82*Kr(p,2n)*sp81*Rb using krypton gas of natural composition as target. The target chamber is designed for a gas pressure of 10 bar. The production unit is dimensioned for a parallel production of five generators, but this number may easily be increased. Attention is drawn to the fact that *sp81m*Rb(31 min) is produced in about the same amount as the *sp81*Rb (4.57 h) ground state. The consequences for the calibration procedure is discussed. Routine production has been exerted without major difficulties for nearly 1.5 years. The procedure has proven to be inexpensive and reliable. (Auth.)