Radiation detector and an arrangement with the same

It is specified with a plurality of detector cells arranged in a detector cell array, a radiation detector, wherein: the detector cells each having an active area and are formed for radiation detection, the radiation detector is adapted such that radiation to be detected via a radiation passage area of ​​the respective detector cell in enters this detector cell and the detector cell with a cell signal is generated during operation of the radiation detector by means of the free charge carriers in the active region is absorbed by carrier generation, the respective detector cell is adapted to generate free charge carriers by avalanche multiplication, the radiation detector comprises a layer which is the radiation through areas of different detector cells, said layer for the radiation to be detected is transparent, and said layer having a first surface that the Detector cells faces, and having a second surface which faces away from the detector cells, wherein a thickness d of the layer is suitably selected.