On the optimality of forest-type file transfers on a file transmission net

A device for detachably securing a collimator to a radiation detector, comprising a first and second annular grooves secured to the radiation detector and the collimator respectively, a split ring having a first and second ring ends and being received in the first annular groove, and a ring diameter control system. The latter one includes a rotating hub and a first and second lever systems connected between the first and second ring ends and the rotating hub. By rotating the hub the ring ends are spread by the lever systems between a first position, where the split ring is alone positioned in the first annular groove, and a second position, where the split ring is arranged in both the first and second annular grooves, thereby attaching the collimator to the radiation detector.