Effective Window of Silicon Surface Barrier Counters

The window of surface barrier detectors is an important source of error in energy measurements for protons and heavier ions. Two methods were used to measure the thickness of this window. In the first the pulse height defect was measured for protons and deuterons as a function of the particle energy. The results show that the window includes the gold layer plus a dead region of silicon (or oxide), the thickness of which depends upon the applied bias. In the second method, the detector was used as a photodiode, and the absorption of light at values of wave length between 0.4 and 0.6¿ was measured. The values of thickness (¿ 1000 Å) of the dead region in silicon obtained by these two methods are in good agreement.