The Frisch grid

The Frisch grid is named after the austrian–british physicist Otto Robert Frisch.Basically it is a grid made of a conductive material that is typically placed between the cathode and anode in ionization chambers and is  commonly on ground potential or weakly charged.

The Frisch grid brings two advantages:  The height of a puls measured in a ionizationchamber depends on the location of the primary ionizsation. So detectors that cover great dihedral angles will have a bad signal quality. By deflecting the anode with the Frisch grid the dependence of the location of the primary ionization is dramaticly reduced; As a second advantage of a Frisch grid is the improvement of the resolution of time. The pulse rises after the electrones have passed the Frisch grid sothe rise time will be shorter than the rise time without a Frisch grid. As mentioned before the rise time is shorter and the peak is higher, so the Frisch grid improves the quality of the measured signal.